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Jeff Kropp, 60g, March 2005

How to Setup a Planted Tank
Low-Tech Excel Based Planted Aquariums
Estimative Index Dosing
Perpetual Preservation System
Beginner Water Changes
Practical Water Chemistry


How to Setup a Non CO2 Low-tech Planted Tank:

Setting up a planted tank for the first time can be a daunting task. There is a lot of information out there on the net but there aren't any great "All you need to know" guides with all the information put together in one place. In addition, while there are some great forums on planted tanks out there, you will invariably find a lot of conflicting information being fed to you which makes it even more confusing for a planted tank newbie. While there are some great books for planted tank enthusiasts, the average person looking to setup a planted tank does not have the time to read entire books before they setup their aquariums. This was the motivation for me to put this guide together.

I was a planted tank newbie not too long ago and I spent many months scouring internet forums, books and other resources to make sense of it all. I wrote this article to collect my thoughts and everything that I had learned and also to help other people like me...those who were just beginning to dabble in the fascinating world of planted aquariums. This article should give you all the information you need to understand the science of planted tanks and to allow you to start setting up your own low tech planted tank while keeping algae at bay. The article has grown significantly in size so I have added a table of contents for your benefit.

    1. Advantages of Low Tech Planted Tanks
    2. Disadvantages of Low Tech Planted Tanks
  1. Basic Science of Planted Tanks
  2. Things to be wary of
    1. Substrate: Choosing the correct substrate for your planted aquarium
    2. Lighting: Appropriate lighting for low tech tanks
    3. Planting: How to plant your tank during initial setup
    4. Filter: Choosing a good filter for good circulation
    5. Fish: When to introduce them in your tank
    6. Dosing Fertilizers: Weekly dosing regiment to keep your plants healthy
    7. Maintenance: Things to do periodically to maintain your tank
  3. Acknowledgments
  4. Comments and Questions

1. Introduction

Low tech tanks primarily refer to planted tanks which are not actively infused with Carbon dioxide (CO2) and hence do not require all the complicated equipment/paraphernalia/hassle that comes along with using CO2 in your tanks. These tanks use lower light levels than “Hi-tech” tanks and plant growth in general is slower (5 to 10 times) than that seen in CO2 infused Hi-Tech tanks. Whether you choose to go with a low-tech or hi-tech planted tank setup depends on a combination of factors such as your primary motivation/goal for a planted tank as well as the amount of time, effort and resources you are able to spend on your tank. Each method has it's pro's and con's.

The article below describes all you will need to know to setup a low tech planted tank and also compares this method with high tech tanks.

1.1 Advantages of Low tech Planted Tanks

1) No testing and no water changes required (Read: Hassle free! It means that you can leave your tank alone for a week or two and it will still be in great shape).

2) Much lower pruning frequency due to slower growth.

3) Very low fertilizer dosing, and only occasionally.

4) No risk of overdosing CO2 and asphyxiating your fish.

5) If any imbalance occurs in the tank (nutrients, traces, sudden ammonia spike, decaying plants/food), algae growth is much slower than in hi-tech tanks allowing much more time to correct the system for this imbalance.

1.2 Disadvantages of Low Tech Planted Tanks

1) Slower plant growth can be boring for some planted tank owners. If you’re the kind of person who likes pruning and rescaping/replanting very often then you might not enjoy this method as much.

2) It can be harder to grow some types of plants which are very dependent on high CO2 levels for plant growth. However a majority of plants can be grown in these types of tanks, including a lot of the so called “high-light” plants like glossostigma and HC.

If you prefer this hassle free technique for growing aquatic plants and have the patience to wait it out a little longer to achieve your end goals with regards to your aquascaping then read on! If however, you’d prefer a middle-road between low-tech and hi-tech. read my post on Non CO2 Excel ta

2. Basic Science of Planted Tanks

Before we get into how to go about setting up your tank using this technique, I’ll briefly mention the logic behind this method. I should mention right away that most of this article is based on Tom Barr’s excellent work (www.barrreport.com) with planted tanks. I have linked to a couple of relevant threads on his site in the Acknowledgments section at the end of this article.

The lack of CO2 augmentation in a low-tech tank essentially means that the rate of plant growth in such tanks is lower than in hi-tech tanks. Due to the lower growth rates, the rate of nutrient uptake by the plants is also correspondingly lowered. As a result, as in the case of Walstad like tanks, the plants can sometimes even survive purely on the nutrition provided from fish waste and decaying food. The drawback with relying purely on fish waste and fish food for nutrients is that the ratio of N,P,K (Nitrogen, Phosphorous and Potassium) in these are skewed out of proportion and can cause a nutrient imbalance in the long run. This can lead to stunted growth in some plants and can also make it very hard to grow certain types of plants which are specifically sensitive to one or more of these limited nutrients.

To overcome this, what we can do instead is dose N, P, K and traces in very small amounts and occasionally (once a week or once in 2 weeks). To prevent any buildup of these nutrients, we can skip the dosing once every couple of months so that the plants use up any excess nutrients in the water column. In this manner we can pretty reliably maintain a non-limiting amount of nutrients in the tank allowing all the plants to grow without any nutrient related inhibition.

It is important to note that high levels of N,P,K, Fe and traces DO NOT lead to algae. Tom has tested this out extensively and has shown that this is simply not true. On the other hand even small amounts of ammonia (causes could be a mini cycle, decaying plants, fish overloading, insufficient plant mass) as well as fluctuating CO2 levels. Fluctuating CO2 levels are thought to signal to the algae spores to start growing) can trigger algae growth. Also In these low-tech tanks the plants and algae are both limited by low CO2 levels. At low light levels and non limiting nutrients, plants can adapt better to these conditions than algae. It is important to have high plant biomass in the tank so that the plants can quickly cycle any ammonia introduced into the system from decaying food/fish waste.

Do not increase your lighting! Higher light levels along with low CO2 levels make conditions much easier for algae to adapt to. Plants find it harder to adapt to high-light low CO2 conditions while algae can do much better in such situations. It is for the same reason that many times people are able to fix their algae problems in the early stages by simply lowering their light intensity or photoperiod.

Also make sure that you DO NOT perform any water changes at all! The reason for this is that tap water will have a different amount of dissolved CO2 as compared to what is in your tank. If you perform regular water changes you are effectively causing fluctuations in the CO2 levels in your tank which provides a perfect environment for algae to start thriving in. Only perform top offs for evaporated water. (Warning: This no water change rule should only be used for tanks with high plant density. If you have a tank which is lightly planted and you don't plan on having more than a few plants in it, then stick to doing at least 25% water changes every week. The no water change rule only works if you have enough plants in your tank so that they alone can help cycle the tank and maintain water quality. The same goes for overstocked tanks. While you might risk a little algae from the water changes, fish health is top priority and the lack of decent plant mass might cause a rise in ammonia/nitrite levels which could hurt your fish.) Perform large (60-70%) water changes after any major rescaping where you pull out plants from the substrate and move things around. This is to remove any toxins/ammonia that you might have released from the substrate with all the uprooting. Also do not perform such types of rescaping/uprooting any more frequently than once every 3-6 months.

4. How to Setup a Non COLow Tech Planted Tank

4.1 Substrate

Setting up your substrate correctly is very important. In general any type of porous substrate with a high CEC (Cation exchange capacity) such as Flourite, Eco-complete, Onyx-sand, etc. should be great for this technique. It is usually recommended to add a light dusting of peat at the bottom of the tank. Even better, you could use Leonardite (Diamond Black is one brand) at the base in place of peat. It is supposed to be much more stable than peat and doesn’t cause as much of a pH drop as peat can cause if it comes in direct contact with your water column (say when you uproot plants and pull out the lower substrate). Also if possible, definitely introduce mulm from an established tank and filter squeezings from a cycled tank into this newly setup substrate. It will help establish bacteria in your soil much faster.

While some people prefer using soil substrates, and it is certainly a viable option, one has to be wary of some of the risks involved in using soil based substrates. The main problem is that it is hard to know what is in the soil that you are using for your tank. You risk introducing toxins or parasites if the soil is contaminated with them. Also a lot of times soils can keep leaching large amounts of ammonia into the water and this can lead to algae disasters as well as be harmful to your fish. While they are nutrients rich, over time they will lose the nutrients in them, so it is wise to supplement your tank with some additional fertilizers. All-in-all using soil as a component of your substrate is definitely a viable option, but make sure to research carefully and take the opinion of more experienced planted tank enthusiasts before finalizing your soil substrate. Most importantly be aware of the risks and take the necessary precautions to prevent any harm to your tank/fish.

Note – If you wish to use Aquasoil (AS) Amazonia by ADA, then you need to first cycle the soil beforehand and leach out the ammonia before you can use it for this technique. This is because the constant water changes required for aquasoil could potentially cause algae problems. For more info on how to pre-cycle Aquasoil check this link: http://www.theshrimpfarm.com/blog/archives/28

AS is amazing stuff and is definitely the best and most nutrient rich commercial substrate available. Since it is packed with nutrients you could probably get away with no fertilization at all in a Low-Tech Non CO2 technique, save for the occasional dose of traces. However over time as the nutrients in the substrate get used up you will probably need to start dosing some macros again.

4.2 Lighting

Lights play an extremely important role in any planted tank. It is the driving force behind photosynthesis in plants. In the case of low-tech, non CO2 tanks, you need to make sure that you do not go overboard with your lights. Don’t make the mistake of assuming that more lights, kept on for longer periods will make your plants grow better or faster. You will most likely be encouraging algae growth and doing nothing else. Although the Watts per gallon rule is a very general one, it still works well as a basic guideline. For this technique make sure to never go above 2 Watts per gallon, 1.5 WPG being an ideal target. Also remember that we are talking about Wattage of fluorescent bulbs (do not use incandescents…ever! And do not use the “Effective” wattage of fluorescent bulbs for this calculation). Remember that Spiral CFLs are more inefficient so you could lean towards the 2-2.5 WPG regime in their case. On the other hand T5 tubes can be extremely efficient and intense and you should definitely stick to 1-1.2 WPG with T5 tubes. For planted tanks, you should ideally look to have bulbs that are rated between 5500K-8000K. 6500K is a very popular choice.

It is usually advised that when you first setup your tank you should have a photo period of only around 6 hours. After a couple of weeks you can bump it up to around 8-9 hours. You probably shouldn’t push it any higher than that. It’s a good idea to buy an automatic light timer (6-7 bucks in Walmart) to make sure that your plants are getting the same duration of lighting every day. If you go 10 hours on some days and 6 on others then it could lead to algae issues and also throw the plants off of their “routine”.

4.3 Planting

This is very important - You have to make sure that you plant very very heavily right from the get go. Very heavy means that when you look at your substrate from above, you shouldn’t be able to see more than 10-15% of the substrate. The rest of it should be entirely covered with plants. It can be a little expensive to do this, but it is well worth the hassle. Buy lots of cheap, fast growing stem plants and just stick them into your tank. Try to ensure that at least 50% of your starting plants are the fast growing type. They will help soak up the nutrients in your tank and help cycle the tank by rapidly using up any ammonia from fish waste and decaying matter. Once all the plants get established and are growing well, you can slowly phase out the fast growing plants for other plants that you wish to keep. Always make sure to have a high plant biomass which is healthy. Drastic pruning/replanting can lead to algae outbreaks due to a sudden change in the amount of healthy plant biomass in the tank. Following these guidelines will go a long way in ensuring an algae free tank.

4.4 Filter

Make sure that you have a good filter with adequate flow (At least 10-15 times the tank volume per hour) and also make sure that the output of the filter that flows back into the tank is allowed to flow unrestricted so as to create good circulation in the tank. This helps disperse nutrients uniformly among the plants and prevents stagnant areas where plants do not receive nutrients and hence begin to die off giving rise to algae. Also, note that a lot of planted tank folks do not use activated charcoal in their filters as it might pull out some of the nutrients from the tank water. If possible, try getting your filter foam/bio-media pre-cycled by using it in an established tank for a couple of weeks prior to setting it up in the new tank.

4.5 Fish

After setting up your tank give it a week or two to see how it is behaving and if the plants have settled down and have started growing. Also make sure that your water parameters are fine. If this is the case and ONLY if you have also planted very heavily, then you can go ahead and add a couple of algae eaters into your tank. Algae eaters go a long way in keeping your tank spotless and algae free, more-so in such a tank where algae growth, if any, will be very slow and the fish will be able to keep up with it. Otos are regarded as one of the best algae eating fish out there although there are other fish/inverts you could pick too (eg: SAE, shrimps). Some might balk at the idea of adding fish to an “uncycled” tank, but the truth of the matter is that if you have a heavily planted tank in which the plants are healthy and growing, the plants will effectively cycle the tank by immediately consuming any ammonia that is introduced into the system. After 2-3 more weeks if everything is going well and your plants are growing and look healthy you can go ahead and add the rest of your fish. It would be a good idea to add in small numbers over a couple of weeks although many folks have added the entire bio load in one go and haven’t had any trouble.

4.6 Dosing Fertilizers

As per Tom’s recommendations, dose the following once a week or once in two weeks for a 20 gallon tank. If you have a different sized tank, calculate the required fertilizer dose accordingly.

1/4 Teaspoon of Seachem Equilibrium (for traces and Calcium + Magnesium). (1.42 ppm Ca, 0.42 ppm Mg, 3.43 ppm K and 0.02 ppm Fe)

1/8 Teaspoon of KNO3 (Potassium Nitrate) (5.27 ppm NO3 and 3.32 ppm K)

1/32 Teaspoon of  KH2PO4 (Potassium Mono Phosphate) (1.61 ppm PO4 and 0.66 ppm K)

You can use Seachem Flourish, CSM+B or TMG for traces instead of Equilibrium although you would need to calculate the corresponding dosage. (For CSM+B, make a stock solution of 1 tbsp or 3 tsp in 250ml. This is roughly equivalent to a Seachem Flourish bottle. 2mls of CSM+B trace solution, 1x a week for a 10 gallon tank should be fine for a low-tech non excel setup) Basically the above solution is roughly equivalent to regular Seachem Flourish. If you choose to use them in place of Equilibrium, keep in mind that you will then need to add Calcium and Magnesium to your tank by some other means. In addition if you wish to use Seachem Potassium, Nitrogen and Phosphorous, then you can use http://www.aquaticplantcentral.com/forumapc/fertilator.php (registration required) to calculate what dose of your fertilizer of choice you need for your tank size so as to match the ppm levels of the fertilizers listed above.

It is important to note that since you are not going to be performing water changes it is always better to underestimate the required dosage to prevent a buildup of nutrients in the system over time. If you underestimate and notice any signs of deficiency in your plants you can always increase the dose by a small amount. Also make sure to skip a fert dose once a month or two. This will allow the plants to take up any excess nutrients that might have built up over this time (since we are only approximating how much nutrients the plants need) and effectively reset the system in terms of nutrient levels.

Also remember that as you gain more experience with low tech planted tanks, you can always try to experiment and tailor your dosing to suit your tank's nutrient needs. You could start experimenting by dosing leaner and leaner till you see visible signs of nutrient deficiency. Once you achieve this, up the dosing amount by a bit and then you should be balancing the nutrient needs of your plants perfectly.

A Note on Purchasing Fertilizers: I would very strongly recommend that you purchase dry fertilizers such as Potassium Nitrate (KNO3) and Mono Potassium Phosphate (MKP) instead of using commercial products such as the Seachem Potassium/Phosphate line. You will save a ton of money by buying the dry fertilizers and 10-20$ of fertilizers can last you almost a lifetime! You can order fertilizers from the following site: www.aquariumfertilizer.com

To dose the fertilizers just buy a cheap set of measuring spoons (I have a set for 1/64, 1/32, 1/16, 1/8 and 1/4 teaspoons) and dose the fertilizers directly into the tank (dry). Also don't dose both Macro fertilizers (like N, P and K) and Micro (Traces) at the same time/day as they can react and precipitate out in the tank. It is best to dose them on separate days. If you're really lazy like me, you can try dosing them both at the same time but in opposite ends of the tanks.

4.7 Maintenance

Maintenance for low tech planted tanks is fairly undemanding. It involves:

1) Dosing fertilizers once a week or once every two weeks

2) Occasionally skipping the dosing to reset nutrient levels in the system

3) Occasional pruning to ensure good circulation in the tank

4) Gentle gravel vacuuming on occasion to get rid of excess detritus (never do a deep gravel vac)

5) Feed fish every day

6) Do a major (60-70%) water change after any major pruning/rearrangement which involves uprooting plants and moving the substrate around.

Well, that is pretty much it. As you can see from the picture in the beginning of this post, you can create amazing aquascapes using a low-tech technique if you have the patience for it. Additionally it is a lot less hassle and requires a lot less time and effort from your end. Hopefully this article will help you maintain a beautiful hassle-free tank with minimal issues. Good luck with your planted tank endeavors!

If you are looking for inspiration, check out my low-tech 10 gallon planted tank below.

5. Acknowledgments:

Most of this article is based on all the useful information I have gleaned from scouring through the forums at Tom Barr’s site, www.barrreport.com . He deserves all the credit for the content of this article. I’ve just put it all together in one place and added some more stuff to make this more accessible to the planted tank newbie. The original thread related to this technique can be found here:


Also, if you are interested in an easy way to kick start a beautiful foreground carpet of glosso, HC or Hairgrass, make sure to check this thread:


Article reproduced with permission from: 

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Low-Tech Excel based Planted Aquariums: A Guide

Before reading this article, I would highly recommend that you read the article on Low-tech, Non CO2 tanks. That article introduces the concept of low-tech tanks and explains in detail the science of low-tech, non CO2 tanks along with some guidelines for maintaining such tanks successfully. One of the drawbacks of this low-tech method is that plant growth can be fairly slow compared to growth rates seen in CO2 enriched tanks. On the other hand, tanks with pressurized CO2 require you to invest a fair bit of time and money to keep them in shape. The balance between lighting, nutrients and CO2 in these tanks is much more delicate and there is a lot less room for error. Any imbalances in the tank can quickly lead to a massive algae bloom. This article details a middle ground between these two methods wherein Seachem's Excel is used as a source of carbon in the tank.


What is Excel and what does it do?

The active ingredient in Seachem Excel is Polycycloglutaracetal. It is a clear liquid which is quite toxic. Be careful when handling it and make sure to avoid skin/eye contact. Essentially it is a Carbon compound which is assimilated by the plants and used by them during photosynthesis. In this manner it acts as a carbon source and a replacement for CO2 in planted tanks. However the uptake of Excel is not as much as dissolved CO2 in tank water. In lay man’s terms, it takes "more work" for plants to use Excel as a carbon source than it does to use dissolved CO2 directly from the water. As a result, while Excel does boost plant growth in comparison to Non CO2/Non Excel methods, the growth rates will still be slower than in CO2 enriched tanks. Also note that Excel has a half-life of 11-12 hours so it is not active in your tank beyond 24 hours. This is why daily doses are recommended. Also make sure to dose it before your light come on in the tank. Excel is light sensitive so make sure to store it in a dark bottle if you plan to pour it out of the regular bottle.


Advantages of using Excel:

1) Faster plant growth as compared to Non CO2, non Excel, low-tech tanks.
2) Excel is known to act as an algaecide. Many people dose excel in their tanks when they are battling algae and have had great success. What this means is that the daily dosing of Excel will act as a deterrent to algae. This is great news for anyone starting out with their first planted tank.
3) Much easier to use in comparison to setting up a CO2 system.

Disadvantages of using Excel:

1) Excel works great for smaller tanks but it can get pretty costly for larger tanks.
2) Some plants which do not have stomatas cannot be grown with Excel. This includes plants such as riccia, vallisneria, egeris densa, hydrilla and liverworts.
3) Excel is toxic. Be careful when handling!
4) Fertilizing is a must for a healthy tank.


What changes when you use Excel in your tank?

Here I'm going to talk about what you need to do differently in comparison to Low-tech, Non CO2, Non Excel tanks as described here. The main effect of adding Excel is that you boost plant growth rates. As a result it also causes a larger demand for nutrients by the plants. The availability of a carbon source allows us to increase the lighting levels by a bit in comparison to non excel tanks. I will list the changes that need to be made in comparison to the guidelines for non excel tanks.

Lighting: Lighting can be pushed up to 2.5 watts per gallon (wpg) at max. You probably don't want to go any higher than this. As before, in the case of spiral CFLs you could probably go up to 3 wpg due to their inherent inefficiency. With T5 tubes you should probably stick to 1.5-1.75 wpg. If at any point you see signs of algae (assuming you are dosing fertilizers normally), then you should immediately lower your light levels/lower the length of photoperiod or do both. Remember that playing it safe with slightly lower lighting is always a wise choice as you will have less trouble with algae on the whole. Also remember that for tanks smaller than 10 gallons, the wpg rule breaks down. You'd probably need 5-6 wpg for tanks that are 5 gallons or smaller.


Dosing fertilizers and Excel:
A 20 gallon tank using excel should get:

1/8 teaspoon of KNO3, 1-2x a week
1/16 teaspoon of KH2PO4, 1-2x a week
2mls of Seachem Flourish, 2x a week
Seachem Equilibrium 1/8th once a week (Immediately after weekly water change)
50% weekly water change
Dose 1-1.5x the recommended dose for Excel (1 ml for every 10 gallons on a daily basis and 5ml for every 10 gallon after 40% or more water changes).

As you can see the fertilizer amounts are higher than in Non Excel tanks. Also now it is recommended to perform 50% weekly water changes. The reason for this is that over time the excess nutrients in the water will start to build up. As a result we need to use the weekly water change to "reset" the system and bring down the nutrient levels in the water. It also helps maintain the water quality in the tank. Once your tank is well established you can try doing water changes maybe once every two weeks. Also if you are dosing leaner than recommended (with no visible signs of nutrient deficiency in the plants) then you could even try doing water changes once every month. However make sure to at least do them once a month if not more regularly.

1) Dosing fertilizers as recommended above
2) Occasional pruning to ensure good circulation in the tank
3) Gentle gravel vacuuming on occasion to get rid of excess detritus (never do a deep gravel vacuum)
4) Feed fish every day
5) Do a major (60-70%) water change after any major pruning/rearrangement which involves uprooting plants and moving the substrate around.

As you can see, we do not skip dosing fertilizers once a month as recommended with non excel tanks. This is because we are now doing weekly 50% water changes to keep the nutrient levels in check.
All the other things mentioned in the non Excel tank post regarding Fish, Substrate and Planting remains the same for Excel based tanks. That is pretty much it. So what are you waiting for? Get started on your aquascaping you planted tank fiend!  


Acknowledgments: Most of this article is based on all the useful information I have gleaned from scouring through the forums at Tom Barr’s site, www.barrreport.com . He deserves credit for a lot of the content in this article. I’ve just put it all together in one place and added some more stuff to make this more accessible to the planted tank newbie. The original thread related to this technique can be found here : http://www.barrreport.com/estimative-index...o2-methods.html .

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Estimative Index Dosing

From the Barr Report at www.barrreport.comAs this method has become popular, it also has had growth pains. Here are the facts about EI or Estimative Index fertilizing:

1. It was never meant to be applied rigidly.

2. It is a simple concept, provide non limiting nutrients without having to test to do so.

3. Adding non limiting nutrients provides the plants with optimal nutrients so folks can rule out deficiencies.

4. Precise plant nutrient deficiencies are not known for most every aquatic plant. This requires a high level of testing and things like fish food, sediments and other potential confounding factors come into play.

5. If you have lower growth, lower light, then you can make safe assumptions like using less nutrients, again, refer to #1.

6. Algae are not nutrient limited in aquariums with fish and plants. Argue this all you want, but you need to research and see what types of nutrient levels will limit algae. They are extremely low and any fish waste and plant decay, leaching etc is more than enough to supply algae with all they need.

7. 90-95% of all algae related issues are due to improper use of CO2.

8. 90-95% of all algae problems are related to improper use of CO2. There is a good reason to repeat this because folks will forget and blame the nutrient dosing method (and this issue is not limited to just EI, every other dosing routine has the same issues).

9. Measuring CO2 carefully is not easy. It varies, it's influenced  a great deal by circulation, it can change 10X in concentration in less than 30-45 minutes.

No other nutrient can change this rapidly, nor is critical to every other nutrient. Algae take advantage of this variation to germinate and establish.

Be very careful in assuming you are 110% positive you have enough, instead, rule out everything else first, then go about tweaking CO2 and do so slowly, never rush or get impatient.

10. In general, less light is better than more for every method using CO2. This reduces CO2 demand, if you use higher light, consider having methods to reduce it, control it if any issue come up.

11. EI rules out nutrient deficiencies. While this can rule them out, many find that after adding non limiting nutrients, they still have issues. EI is not solely about nutrients, if the CO2 demand was limited because there was not much PO4, now the CO2 demand is greatly increased. 

If the CO2 is not also increased to account for this change, then it can lead an aquarist to incorrectly assume that it is the PO4 that is causing the plant or algae issue. However, it is a secondary effect. If the CO2 was controlled correctly in the test, then the algae/plant issue would not have occurred. Such error/s in logic can lead to false assumptions and conclusions.

12. Make as safe assumptions as you can.

13. Test if you want along with EI. Some do so to get a feel for their aquarium, then no longer test if they are within the target (theirs or EI's etc) ranges. These are choices and trade offs you can make and you decide if they are worthwhile for you.

There is no rule that says you cannot test. I suggested testing along with water changes in the past (see 1996-1997 list of levels of parameters thread here). However, testing correctly is not been one of aquarist best traits These are cheap test kits and with poor resolution, so it is wise to calibrate any test kit before relying on any data obtained from their results. Even 10,000$ lab test equipment is calibrated, this way we know the results are accurate.

14. EI is not based on flowery language, perception or marketing schemes. It is not based on faith. It does not disparage other methods. 

The results are testable, the concept come from PMDD and the math is even in there as well, I simply posed a few graphs.

15. EI is specific to the water column source of nutrients, however; water does diffuse into sediments and can become a source of nutrients to the roots as well. This does not preclude aquarist from using root sediment sources as well in conjunction with water column fertilizers.

16. Ratios. Hot topic and few really understand anything about it and why it does not matter. Epstein and Bloom are two very well respected researchers on this topic and it really gets down to limiting vs non limiting levels much more than a ratio (see their text: Mineral nutrition of Plants, Principles and Perspectives, 2005). Ratios can save the farmer spending 1000$ on fertilizers and reduce their runoff waste, however, aquarist do not have issues here and the cost is insignificant. 

Still, a relative range of ratios is not bad either, but with the wide range of species kept and each one having their own set of growth rates, nutrient demands, this seems very difficult to apply in a general way.

17. RR or Redfield ratio is often discussed and cited and folks make a mistake in mass vs atomic number of atoms. A ratio of atoms, number, is 1 P for each N according to marine algae in Redfield's paper. This is not mass. P is 30.97 grams per mole. N is 14.01 grams per moles. To convert to mass, you need to multiply N by 2.2, now the RR is 7:2 1, or about 10:1 for NO3/PO4.

Still, this is just what is available from upwelling in ocean systems and is typically under extremely high light, full sun etc. The system becomes limiting after prolonged algae growth. This is radically different from what occurs in freshwater systems where aquatic plants are involved. Fresh water plants have different ratios, different nutrient sources and cycling, as well as being able to concentrate nutrients from their external surroundings at a much high gradient internally.

18. Inhibiting levels of nutrients, the upper bounds. Generally, this is from osmotic conditions, too much salt basically. Hoagland's modified solution is very rich and is a non limiting nutrient solution. EI is just a similar idea but on the lower end for aquatic plants, above the limiting ranges but not nearly as rich. Hydroponics and Hoaglands solution has a very long history and test/research background for support. EI is no where even remotely close to these levels of inhibition.

19. Less light = less demand for nutrients. You can go too far and get so low plants will not grow no matter what the CO2/nutrients, however, it's a very useful way to control the rates of growth for an aquarium and also to control algae until the conditions are corrected. Many have issues with CO2, so using less light makes targeting a good stable CO2 level much easier than say higher light intensity. Thus limiting light makes the most logical sense, not nutrients and CO2 for algae control, for stability, for CO2 issues/nutrient issues, for control of growth rates, for less electrical use, reducing heat, reduction of any and all waste.

20. If the CO2 is not properly added, then EI, nor most any other method (unless it limits a nutrient so much that CO2 decreases) will help you. Severely limiting PO4 can reduce CO2 demand, but can be difficult to keep doing. Might as well just use less light, since that's where all growth starts. You see? Lots of CO2 talk, very little about nutrients...

21. It is an INDEX, any index simplifies reality; and thus has inherent limitations like any index or indices, such as the stock market, economic forecasting or species diversity. Any attempt to compress complex data into a single index will suffer some loss of information.

That's why I chose to refer to it as EI, not something cheesy like Tom's wonderful magic potion of plant growth. This index is fairly robust because of what went into the general concept, it assumed the highest possible rates of growth at the upper limit. So we will essentially never run out of any fertilizer. EI does not nor any other nutrient method done much with CO2 or light (EI just used an upper possible bound with respect to light) So if you mess up CO2, which most/many aquarists do at some point (either application or measurement errors and assumptions), then algae, or poor results are not independent of light and CO2, they become dependent.

A nutrient method cannot be judged unless those other two main players in plant growth and fully addressed, this has long lead to confusion and blame.

Most hobbyist just want good plant growth and no algae issues. They rarely do test to illustrate and confirm independence in such test systems and experiments. A good way to do it: have a nice tank without algae and good growth of plants. That makes the best control for falsifying something, but will not tell you what something might be with certainly.  Regards, Tom Barr

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Perpetual Preservation SystemTM

The most accurate Aquatic plant fertilizers


Chemicals & Dosing

The elements plants need are available as safe chemicals that are simple salts, called fertilizers. They are in essence dissolved natural rocks similar to mineral water drinks. These fertilizer chemicals have been produced and used by agriculture and horticulture industries to grow plants for decades. The aquarium fertilizers are not different for the reason that almost all are made of the same chemicals. The only difference is in the application technique. 


What chemicals do I need to order?
K2SO4 Potassium sulfate
KNO3 Potassium nitrate
KH2PO4 Monopotassium phosphate
MgSO4 Magnesium sulfate
CaSO4 Calcium sulfate (optional)
TE Trace Element Mix, Plant-Prod Chelated Micronutrient Mix (2% Mn, 7% Fe, 0.4% Zn, 0.1% Cu, 1.3% B, 0.06% Mo) or CSM+B Plantex 

Where can I get the chemicals from?
There are many options where to get the chemicals. 

http://www.hydroponics.com part of Six-Pack Nutrient Line, #2 to #6
http://www.theplantguy.org in Canada
http://www.plantprod.com large quantities only


MgSO4 is also available as Epsom salt in Drug Stores, Walmart and Pharmacies as bath salt.
Trace Element Mix can be substituted by any local fish store good Trace Element product containing the same elements. (2% Mn, 7% Fe, 0.4% Zn, 0.1% Cu, 1.3% B, 0.06% Mo)

How long will dry chemicals last?
There is no expiry date on dry chemicals. As long as they are kept dry in sealed bags they are ok.

Can I mix chemicals together?
Not recommended unless specified by Solutions Recipes.


How often do I dose?
Both, PPS-Classic and PPS-Pro are designed to be dosed daily at the same time. Just like feeding fish, feeding plants.

When do I dose?
The best time to dose is anytime before lights go on so the nutrients are available for photosynthesis. Daily dosing before lighting period starts, helps maintaining better balance, higher plant uptake and healthier plants.


Can I dose Macro and Micro at the same time?
Simply dose both at the same time into moving water.


How much do I need to dose?
For PPS-Pro see text below.
For PPS-Classic dose is variable depending on PPS-Classic Dosing Calculator results. 

What's the difference between PPS-Classic and PPS-Pro?
Both systems can support lighter planted, heavily planted, low light and high light conditions.

PPS-Classic dosing quantity is determined by the PPS-Classic Calculator. The calculator needs to know a dosing period (one or more weeks or months), NO3 and PO4 water column levels at the period start and the period end. Then the calculator result gives the next dosage quantities needed to reach the chosen target levels. Additional benefit is the output statistics like, Present daily dosage in ppm, Present daily plant uptake in ppm and Next recommended daily dosage in ppm. It is a highly flexible system with analysis that can maintain any water column levels.

PPS-Pro is a simplified version taking into account most common planted aquariums. It works well when common sense conditions are met. Expected is a heavily planted aquarium with reasonable fish load. An aquarium with one Cryptocoryne and a Goldfish will not work smoothly. Also, daily dosing before lighting period starts, helps maintaining better balance, higher plant uptake and healthier plants. For lower light aquariums use half the recommended dose, for medium light use recommended dose, for very high light use double the recommended dose. Although some monitoring of NO3 levels from time to time helps to determine better dosing quantity. This system can maintain very low, medium or very high water column nutrient levels as desired.

How do I start PPS-Pro?
We all know new setups are challenging. Plants need time to adapt to new conditions.
To begin, aquarium water can start at any nutrient levels. Then we start dosing daily PPS-Pro solution #1 (Macros) at 1 ml per 10 gallon or 40 L and PPS-Pro #2 (Trace elements) at 2 drops per 10 gallon or 40 L. (Daily dose of 1 ppm NO3, 0.1 ppm PO4, 1.33 ppm K, 0.1 ppm Mg, 0.01 ppm Fe(TE)) 

During this time and in to the future we need to switch from test kits to conductivity readings. This is easier, cheaper, faster and more accurate to overall living condition. Everything in an aquarium, alive or not, has some relationship to conductivity. TDS-tester 

The way it is done is to maintain consistent levels of pollutants, like fertilizers, substrate leaks, fish waste, decoration leaks and other with water changes. Some setups involve large water changes at times, and some more balanced, not so much. That’s the beauty. Plants and fish love consistency. 

For example, when your tap is 300 µS, one PPS-Pro daily fertilizer dose is 6µS. This one dose is 1 ppm of NO3. So to limit the NO3 to theoretical 15 ppm we need to make sure the conductivity reading is kept under (6 x 15) + 300 = 390 µS with water changes. 

If you feel like needing more fertilizer then there is no problem to dose more ml of the PPS-Pro solutions. The conductivity reading will take care of it and balance it out.
(1 ml = 20 drops)

What is the PPS-Pro conductivity TDS target range?
Water change IF ( aquarium µS ) > ( tap + 100µS ) 
Tap 300 µS + PPS-Pro 100 µS = 400 µS
If ( aquarium µS ) > 400 then water change 

How to do PPS-Pro with water changes?
Easy, no worry approach. Dose PPS-Pro Solution #1 and PPS-Pro Solution #2 at the same time daily for a week, then 50% water change.

Low light
PPS-Pro Solution #1, 0.5ml or 10 drops per 10 gallon or 40 L
PPS-Pro Solution #2, 1 drop per 10 gallon or 40 L
Water change 50% once a week
This limits water column nutrient levels to 7 ppm NO3, 0.7 ppm PO4, 9 ppm K, 0.7 ppm Mg, 0.07 ppm Fe(TE).

Medium light
PPS-Pro Solution #1, 1ml per 10 gallon or 40 L
PPS-Pro Solution #2, 2 drops per 10 gallon or 40 L
Water change 50% once a week
This limits water column nutrient levels to 14 ppm NO3, 1.4 ppm PO4, 18 ppm K, 1.4 ppm Mg, 0.14 ppm Fe(TE).

High light
PPS-Pro Solution #1, 2ml per 10 gallon or 40 L
PPS-Pro Solution #2, 4 drops per 10 gallon or 40 L
Water change 50% once a week
This limits water column nutrient levels to 28 ppm NO3, 2.8 ppm PO4, 36 ppm K, 2.8 ppm Mg, 0.28 ppm Fe(TE).
(1 ml = 20 drops) 

What if I cannot get KNO3 to make PPS-Pro #1 macros solution? 
Some countries restrict KNO3 availability. You can still make the original PPS-Pro solution #1 macros without KNO3 and make additional solution #1 macros KNO3 substitute with Ca(NO3)2. 

PPS-Pro #1 macros KNO3 substitute, 1 ppm NO3, 0.63 ppm K, 0.32 ppm Ca
Daily dose 1ml per 10 gallon or 40L, 53% solubility
500 ml
28 g K2SO4
38 g Ca(NO3)2.4(H2O)
Dose with PPS-Pro #1 macros without KNO3 at the same time and the same quantity.

What is the difference between Plant-Prod Chelated Micronutrient Mix and Plantex NutriTrace CSM+B?
Plant-Prod Chelated Micronutrient Mix is almost the same as Plantex NutriTrace CSM+B. The difference is in chelating.

Plant-Prod Chelated Micronutrient Mix
EDTA (Ethylene diamine tetraacetate) 42%, (5% Fe, Mn, Zn, Cu) 
DTPA (Diethylene triamine pentaacetate) 14%, (2% Fe)

Plantex NutriTrace CSM
EDTA (chelating agent) 65.4%, (7% Fe, Mn, Zn, Cu)

is added by resellers.

Can I have zero nutrient levels?
Zero nutrient levels should not occur.


Chemical Tables
For reference only.


Edward PPS™ Copyright ©2004 - 2009

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Beginner Water Changes

I use municipal tap water in my aquarium. What do I need to know?

Most people use tap water in their tanks; it is easiest (and cheapest) to use. Unfortunately (for aquarists), local water companies add chemicals to the water to make it safe to drink (e.g., by adding chlorine or chloramine to kill bacteria). More recently, concern about water flowing through (older) lead pipes has caused some water utilities to add pH-raising chemicals to the water (lead dissolves less readily in alkaline water). Consequently, tap water must be specially treated before it can safely be used in fish tanks.

Another potential problem to be aware of concerns variability in the chemical properties of your water supply over time (e.g., month-to-month). Some water districts don't have enough water themselves, forcing them to purchase additional water from neighboring water districts in times of shortages. If this water has a different hardness (for example), your tap water's hardness will vary as well. As a common example, high bacteria levels are more of a problem in summer than winter, especially in warmer climates. Consequently, it is not uncommon for water companies to use more chlorine in summer months to keep bacteria in check. Even such factors as local weather can have an impact; heavy rains may cause the hardness of your water supply to decrease, as local reservoirs fill.

In general, chlorine and chloramine are the two additives that cause the most problems. Note that these two substances are VERY DIFFERENT! Be sure you know what is in your tap water and treat appropriately.

What do I need to know about chlorine?

In the US, EPA guidelines require that tap water at any faucet contain a minimal chlorine concentration of .2 ppm, and stringently limits the concentration of bacteria (which may require more than .2 ppm chlorine to keep in check). Because chlorine breaks down over time, the chlorine concentration of the water that comes out of your tap will be lower than that put in at water plant. Thus, the exact concentration at your faucet depends on how far you are from the water plant, how long it takes the water to travel from the water plant to your house, how much chlorine is initially added, etc.

Chlorine at high concentrations is toxic to fish; at lower concentrations, it stresses fish by damaging their gills. Concentrations of as little as .2-.3 ppm kill most fish fairly rapidly. To prevent stress, concentrations as low as 0.003 ppm may be required. Fortunately, chlorine can easily be removed from water by the chemical sodium thiosulfate, readily available at fish stores under various brands. Sodium thiosulfate neutralizes chlorine instantly. Note that there are many "water treatment" products that are advertised as "making tap water safe". Read labels carefully. Inevitably, the ones that neutralize chlorine all contain sodium thiosulfate, plus other substances that may or may not be useful. If your water only contains chlorine (as opposed to chloramine), sodium thiosulfate is all you need. The most cost-effective treatments use only 1 drop per gallon of water. Most other water treatments are much more expensive in the long-term; they may require a teaspoon of treatment (or more) per gallon!

Chlorine is relatively unstable in water, escaping to the atmosphere on its own. Water left in a bucket (or tank) with adequate water circulation (e.g. filter or air stone) will be free of chlorine in 24 hours or less.

Many netters report that they perform partial water changes without ever treating their tap water to remove chlorine. Keep in mind that even though fish show no apparent ill-effect from untreated water, that doesn't mean that the chlorine isn't stressing your fish. How much stress depends on how much chlorine is introduced to the tank, which depends on many factors (including the percentage of new water added). Because chlorine removers are so cheap (pennies per usage), the insurance they provide should not be passed up.

What do I need to know about chloramine?

One problem with using chlorine to treat water is that it breaks down relatively quickly. Another concern with the use of chlorine is that it can combine with certain organics (that may or may not be present in your water) forming trihalomethanes, a family of carcinogens. Consequently, many water companies have switched from using chlorine to using chloramine. Chloramine, a compound containing both chlorine and ammonia, is much more stable than chlorine.

Chloramine poses two significant headaches for aquarists. First, chlorine-neutralizing chemicals such as sodium thiosulfate only neutralize the chlorine portion of chloramine, neglecting an even bigger problem: deadly ammonia. The consequences can be devastating to fish. Although a tank's biological filter will (eventually) convert the ammonia to nitrate, the time it takes to do so may be longer than what your fish can tolerate.

The second problem relates to water changes. One of the primary reasons for doing regular water changes is to remove nitrates that build up. If your replacement tap water contains ammonia, you'll be putting nitrogen right back into your tank and it will be impossible to reduce the nitrates below the concentration in your tap water. Fortunately, tap water concentrations are relatively low (1 or 2 ppm); you are more likely to have a much higher concentration of nitrate in your tank.

Chloramine can be safely neutralized through such products as Amquel, which neutralize both the ammonia and chlorine portions of the chloramine molecules. The neutralized ammonia will still be converted to nitrates via a biological filter.

Another method for neutralizing chloramine is to age it while simultaneously performing biological filtration. For example, get an appropriately-sized (plastic) garbage can, fill it with tap water, dechlorinate it with sodium thiosulfate, and then connect an established biological filter to it. Just as in your tank, the bio filter will convert the ammonia to nitrate, after which it can safely be added to your tank. Note: you must add sodium thiosulfate to neutralize the chlorine; otherwise, the chloramine will kill the bacteria in your biological filter.

Alternatively, the ammonia can removed by filtering the water through zeolite or carbon before adding it to your tank. [Note: folks report mixed success with this. If you have concrete (positive or negative) experience to report, please notify the FAQ maintainers.

Are there any other water impurities that I should be aware of?

Quite possibly. In addition to the additives described above (chlorine & chloramine), municipal water may (or may not!) contain other elements that the aquarist may need to know about about. Water in some locations actually contains nitrates. In some places, water contains elevated concentrations of phosphates (1 ppm or more). High phosphate has been linked to algae problems, and a comprehensive algae control strategy may require removing phosphates. High levels of iron (1 ppm or more) have also been linked to thread algae. Consult the algae section of this FAQ for more details.

How do I find out just what my local water company is adding to the water?

The quick answer is to ask someone who knows. A local fish store (if they reside in the same water district as you do) should be able to tell you. Alternatively, call your local water utility. Ask to speak with the "water chemist". Tell them you are an aquarist and want to know about the pH, GH, and KH of your water, as well as how much the water characteristics vary from month to month. Finally, (in the US) if you really want details, have them send you a copy of the periodic water report they are required to generate for the EPA. It contains a detailed listing of exactly what your water contains and in what concentrations (e.g., iron, nitrates, phosphates, etc.). By law, the report is available for public inspection.

I don't have city water. Can I use my well water?

Yes. One advantage with well water is that you don't need to deal with chlorine and chloramine. On the other hand, well water is frequently (much!) harder than water available through local utilities. In addition, the only way to know its composition (GH, KH, etc.) is to run tests on it yourself. Alternatively, there are companies to which you can send water samples that will perform a detailed analysis of its contents (for $20-100).

One potential problem with using well water is that it frequently contains high concentrations of dissolved gases (e.g., dangerous to fish). For example, well water is frequently supersaturated with CO2, which lowers the water's pH. Once the CO2 escapes, the pH will increase. Fish shouldn't be subjected to this temporary pH fluctuation. For safety, aerate well water thoroughly for several hours before adding it to your tank.

What test kits should I get, and when are they useful?

There is a seemingly endless array of test kits for testing everything from ammonia levels to phosphate levels. Does one really need to buy them? The quick answer is no. It is quite possible to have a healthy tank without ever buying a single test kit. However, test kits are extremely useful at eliminating guesswork when something goes wrong (e.g., fish appear stressed or die). In the following, we describe the test kits that are most useful and the conditions under which they are useful.

Should I get an ammonia test kit?

Yes. Ammonia test kits are cheap ($5-10) and will tell you whether your tank has elevated ammonia levels. This is useful in two circumstances. First, during the tank-cycling phase, regular testing for ammonia will tell you when the first phase of the nitrogen cycle has completed. Second, should you have unexplained fish deaths, testing for ammonia verifies that your biological filter is (or is not) working correctly. Note that even in an established tank, the biological filter can sometimes weaken or fail outright. Common causes include not cleaning it regularly (water can't flow through a clogged filter, where the nitrifying bacteria reside), naively adding fish medicines (antibiotics kill nitrifying bacteria (oops) as well as disease carrying ones), having too small a filter for the fish load, etc. Be warned: If you have fish deaths and subsequently ask the net (or a fish store) for advice, the first question asked will be "What are your ammonia (and nitrite) levels?".

Ammonia levels are measured in ppm. At concentrations as low as .2-.5 ppm (for some fish), ammonia causes rapid death (also consult cycling section for further details). Even at levels above 0.01-0.02 ppm, fish will be stressed. Common test kits don't register such low concentrations. Thus, test kits should NEVER detect ammonia in an established tank. If your test kit detects ANY ammonia, levels are too high and are stressing fish. Take corrective action immediately (see question XXX). Warning: Amquel and other similar "ammonia-neutralizing" water additives are incompatible with most ammonia test kits. Water treated with Amquel will falsely test positive for ammonia, even when ammonia is not present. Test kits sold under the brand names XXX are known to give false readings under such conditions.

Should I get a nitrite test kit?

Maybe. Nitrite kits are cheap ($5-10) and are useful in the same circumstances where an ammonia test is useful. The only time a nitrite kit provides information that an ammonia kit can't is while testing for completion of the second phase of the nitrogen cycle. As in the case for ammonia, if your test kits detects nitrite, your biological filter is not working adequately. Once a tank has cycled, nitrite kits are pretty much useless. (If the bio filter in an established tank isn't working, both ammonia and nitrite levels will be elevated.)

Nitrite is an order of magnitude less toxic than ammonia. Thus, one common saying about tank cycling is: "if your fish survive the ammonia spike, they'll probably survive the nitrite spike and the rest of the cycling process." However, even at levels above .5 ppm, fish become stressed. At 10-20 ppm, concentrations become lethal.

Should I get a nitrate test kit?

Yes. Nitrate levels increase over time in established tanks as the end result of the nitrogen cycle. (The only exception to this rule is HEAVILY planted tanks, which are SOMETIMES able to consume nitrogen faster than it is produced.) Because nitrates become toxic at high concentrations, they must be removed periodically (e.g., through regular water changes). Having a nitrate test kit helps you determine whether or not your water changes are removing nitrates quickly enough.

Nitrates become toxic to fish (and plants) at levels of 50-300 ppm, depending on the fish species. For fry, however, much lower concentrations become toxic.

Note: A nitrate test kit is only of limited value in determining whether the nitrification cycle has completed. Most nitrate test kits actually convert nitrate to nitrite first, then test for the concentration of nitrite. That is, they actually measure the combined concentration of nitrite and nitrate. In an established tank, nitrite levels are essentially zero, and the kits do properly measure nitrate levels. While a tank is cycling, however, a nitrate kit can't tell you how much of the reading (if any) comes from nitrate rather than nitrite.

Should I have a pH test?

Yes. You will want to know the pH of your tap water so that you can select fish whose requirements meet your water conditions. In addition, you will periodically want check your tank's pH so that you can be sure it stays stable and doesn't increase or decrease significantly over time.

In some cases, tank decorations (e.g., driftwood) or gravel (e.g., of made of coral, shells or limestone) change the pH of your water. For example, tank items may slowly leach ions into your tank's water, raising the GH and KH (and pH). With driftwood, it is not uncommon to have the wood slowly leach tannins that lower the pH.

Should I get a test kit that measures general hardness (GH)?

Maybe. You may want to get one of these, but having one is not critical. You don't need to know the exact hardness level. Knowing whether your water is "soft", "very soft", etc. is good enough. Your local fish store may be able to give you sufficient information. Alternatively, call your water utility.

Should I get a test kit that measures carbonate hardness (KH)?

Maybe. This kit is not critical to have. By regularly monitoring the pH, you can figure out whether your KH is "high enough". That is, the KH should be high enough that your pH stays stable over time. If you have trouble keeping the pH stable, you may want to increase its buffering capacity. Your local fish store may be able to give you sufficient information as to your KH value. Alternatively, call your water utility.

What is the purpose of regular water changes, and how frequently should they be done?

The solution to pollution is dilution; water changes replace a portion of "dirty" water with an equal portion of clean water, effectively diluting the concentrations of undesirable substances in your tank. In an established tank, nitrate is the primary toxin that builds up. Regular water changes are the cheapest, safest and most effective way of keeping nitrate levels at reasonable levels. During the tank cycling phase, however, ammonia or nitrite may be the substances that need to be diluted and removed. Likewise, if medications have been added to your tank, they may need to be removed after they've served their primary purpose.

The effectiveness of water changes is determined by two factors: their frequency and the percentage of water that is replaced. The more often water is replaced, or the greater the quantity of replaced water at a change determines overall effectiveness.

The benefits of water changes must be balanced by the stress caused by a sudden change of your tank's water chemistry. If tank water has similar pH, GH and KH as tap water, changing 50% (or more) of the water at one time will not affect fish. On the other hand, if your tank's pH is (for example) 6.3, while your replacement water has a pH of 7.5, replacing 50% of the water all at once will change the pH of your tank significantly (possibly more than 50% depending on buffering factors), which will stress your fish, possibly enough to kill them.

Because water changes are the first line of defense in dealing with problems such as disease, you want to be able to do large, frequent partial water changes during emergency periods. Consequently, you want your tank's water chemistry to closely match that of your replacement water. That way, you always have the option of performing large water changes on short notice. Note that this is the way tanks start out; when you initially set up your tank, the water is the same as that from your tap. Over time, however, the tank's water chemistry may "drift" relative to tap water due to acidification from the nitrification cycle, the addition of chemical additives such as "Ph-up" or "Ph-down", the use non-inert tank gravel (e.g. crushed coral or sea shells), etc.

How frequently should partial water changes be made?

The more frequent the changes, the less water that needs to be replaced. However, the longer between changes, the more stressful changes potentially become, because a larger portion of the water gets replaced. Replacing roughly 25% of your tank's water bi-weekly is a good minimal starting point, but may not be enough. The proper frequency really depends on such factors as the fish load in your tank. Nonetheless, you should do water changes often enough so that:

  1. Nitrate levels      stay at or below 50ppm, and preferably MUCH lower (less      than 10ppm is a good optimal value).
  2. The change in      water chemistry resulting from a change is small. In particular, the      before and after pH of your tank shouldn't differ by more than .2 units.      (Use a test kit the first few times to get a feel for what's right.) If      your pH changes too much as a result of a water change, perform changes      more frequently, but replace less water at each change.

Water changes remove nitrates after they've been produced. Nitrogenous substances in the form of uneaten fish food, detritus, etc. can also be removed BEFORE they get broken down into nitrate. This is achieved by cleaning your mechanical and biological filter regularly, and by vacuuming the gravel with a gravel cleaner. This should be done every time you perform a water change, e.g., every two weeks.

Note: if your heater becomes partially exposed to air as the water level drops while doing changes, be sure to unplug your heater while doing your water changes. The heater can crack if the water level drops below the heating coil!

Also, be sure to dechlorinate/dechloramate the replacement water before adding it to your tank! (see section XXX)

How many fish can I put in my tank?

This is a tough question and cannot be answered by a simple formula, though many are given in books. The answer is determined by:

  • What species of fish does your tank contain? Many      fish have minimum space requirements independent of the number of      tankmates. For example, angelfish (eventually) need at least a 20g. Most      fish that get longer than 1.5 inches need to be in a tank larger than 10g.
  • Is your biological filter large enough to handle      the tank's bio-load? Some fish produce more waste than others of the same      size, so the answer depends on the species of fish, their sizes, as well      as their numbers. Goldfish, big cichlids (e.g., Oscar fish) produce much      more waste than other fish of the same size.
  • How much surface area does your tank have? A      "long" tank can generally support more fish than      "high" tank of the same volume; the increased surface area      provides more oxygen exchange and provides more length-wise swimming room.

Is it safe to put driftwood (or whatever) in my tank?

It is safe to place items in your tank as long as they are inert. Most plastics are inert (safe), as are glass and ceramic.

Wood may leach substances into the water, changing the pH in a (possibly) inappropriate manner. Driftwood often leaches tannins and other humic acids into the water (much like peat moss), possibly softening it and lowering its pH. The water may also obtain a yellowish tea-colored tint. The tint is not harmful and can be removed by filtering the water through activated charcoal.

If you use wood that you've found yourself (e.g., woods or lake), boil it first to kill any pathogens. Boiling it (long enough) will also make it sink.

How much (and how often) should I feed my fish?

Out in the wild, food is not plentiful year round. In comparison, your tank is a feeding trough. Chances are, fish will get much more food in your tank than in the wild. Thus, the problem to avoid is overfeeding, rather than underfeeding. Fish are also smart (in the sense of Pavlov's Dog) that they learn quickly how to train their masters into giving them food. Just because they act starved when you walk by the tank an hour after their last feeding, doesn't mean they actually are. Look at the abdomens on your fish. If they are fat and bulging, your fish isn't starving. If they are thin, or hollowed out (concave upward), you may want to consider increasing the feeding.

Fish can be safely fed twice a day, once a day (or less). If your goal is to maximize growth, feed them more frequently, but smaller portions.

There is an old rule that says fish should be fed no more than they eat in 5 minutes. Like most general rules, this one is only partly correct. What you really want to avoid is having food to rot in your tank uneaten, which negatively impacts water quality. However, some fish eat food slowly and will take 30 minutes to eat even a small portion.

How long can fish go without food? Healthy fish can easily go a week without food. When you go out of town for the weekend, don't bother getting someone to feed your fish. (Indeed, someone not familiar with fish tanks is likely to overfeed your fish while you are good, leaving you a mess to deal with when you return.) In addition, stay away from those "vacation feeders" that slowly dissolve. They can upset the pH of your tank and lead to excessive food in your tank.

What should I feed my fish?

There are endless varieties of fish foods available from local stores. The best fish diet is a varied diet. Rather than feeding them only one type of food, give them several types, at alternate feedings.

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Practical Water Chemistry by Shelli Wittig (Fishgal)

Water chemistry can be a bit daunting to the beginner aquarist; at least it was for me. When I got started in the hobby I was sold a complete test laboratory which included tests for 5 different things. I was diligent about testing and recording the results, but never had a very good understanding about what these properties were and how they affected my fish. This made it very difficult to actually use any of the data I was collecting.


As it turns out, it’s not really all that complicated. Fish keepers are mainly concerned with how acidic or alkaline the water is, and what concentration and variety of dissolved minerals it contains. These are expressed by measuring three basic properties: pH, GH and KH.


pH is probably the single most important property to understand and monitor. It refers to water being acidic, basic (alkaline) or neutral. With a measurement of 7 being neutral, less than 7 is acidic and greater than 7 is alkaline. While common tropical fish are happiest right around neutral, African cichlids prefer the following alkaline ranges:


    Lake Malawi species:    7.4 - 8.6

    Lake Tanganyika species:    7.8 - 9.0

    Lake Victoria species:    7.2 - 8.6


Fish are extremely sensitive to changes in pH and it is important to maintain a stable level in your aquarium. When adjustment is necessary, avoid changes greater than .3 units per day. Keep in mind that the pH scale is logarithmic (like the Richter scale used to measure the intensity of earthquakes). This means, for example, that a pH of 8.0 is 10 times more alkaline than a pH of 7.0.


General hardness or total hardness is a measure of the magnesium and calcium in the water. Africans are most likely to appear vibrant and colorful in aquariums with a general hardness ranging from 160-320 ppm (ppm) or 9-18 dH (Deutsch hardness). Because dH values refer to a German hardness scale, I have heard GH mistakenly referred to as German hardness which is incorrect. This is a mix-up between the particular water property being measured and the scale on which the result is expressed. There is also a Clark scale, but since I am not personally familiar with it and don’t know how widely it is used I chose not to calculate the target range using that scale. Examine your test kit carefully so that you are certain what scale it uses. The following conversion table may be helpful: 1 dH = .65 Clark = 17.9 ppm


It should be noted that GH levels naturally drop over time because minerals do not stay suspended in water very long. This is one of many good reasons for regular partial water changes.


KH or carbonate hardness, also known as buffering capacity or total alkalinity, is a measurement of carbonates and bicarbonates in the water. It is best described as water’s ability to keep the pH stable as acids or bases are added almost acting like a sponge for those additives so they cannot affect the pH. Without adequate buffering, the pH in your aquarium will eventually drop because the end result of the nitrogen cycle is nitrate (nitric acid), which slowly builds up between water changes. With sufficient buffering the pH remains stable. For a Rift Lake aquarium, KH is ideally in the range of 180-240 ppm, or 10-14 DH.


Do I really want to tamper with these properties? Some people are diligent about testing and taking calculated steps to achieve specific targets, while others defiantly reject that approach and claim to have a thriving aquarium without complication or added expense. I believe that success with the latter would not be without a fair degree of luck. Some hobbyists are fortunate to have hard water with a high pH right out of the tap and still others have selected species that are more adaptable than others to unnatural conditions.


With a little experimentation and application of the basic knowledge derived here, you can take a more proactive approach and perhaps even find that the challenge of creating the perfect water chemistry makes aquarium maintenance more fun. You will be rewarded with healthy, colorful fish that flash their fins, exhibit natural behavior and even spawn. More importantly, you are much less likely to have to deal with unexplained illness or death.


How do I make changes? To raise KH and pH, add baking soda (sodium bicarbonate). A baseline recommendation is 1 teaspoon per 5 gallons of water (dissolve in a cup of aquarium water if adding directly to the tank). For an established aquarium, remember to take this slowly as fish are highly sensitive to pH changes. Incidentally, there are off-the-shelf products available for this purpose, but baking soda is cheaper and most people already have it on hand. Wardley’s product Raise pH® is sodium bicarbonate, whereas Aquarium Pharmaceuticals pH Up® is sodium hydroxide.


Instead of relying solely on additives for buffering, you can use crushed coral, crushed oyster shell, crushed limestone, aragonite or dolomite as a substrate. Seashells, limestone rock or Texas Holey Rock (also limestone) will all help to provide continuous buffering as they leach carbonates into the water.


Driftwood (use only safe and sterile pieces intended for introduction into an aquarium) will leach tannic acid and consequently lower pH. It can discolor the water as well, and is typically not recommended for Rift Lake aquariums. Sodium biphosphate reduces pH, and pH Down® by Aquarium Pharmaceuticals contains sulfuric acid to accomplish the task. I consider intentionally lowering pH a tricky and dangerous business because it is impossible to do without affecting KH. You must first use up the buffering capacity and then any further steps you take will immediately lower the pH. The danger is that with no buffering capacity remaining, your resulting lower pH is extremely susceptible to fluctuation. Luckily, African cichlids like a high pH and most of us need never take any steps to lower it.


To raise GH, add Epsom salt (magnesium sulfate). A baseline recommendation is 1 tablespoon per 5 gallons of water (dissolve in a cup of aquarium water if adding directly to the tank). While adjusting total hardness is not as potentially dangerous to your fish as adjusting pH, dramatic changes of any sort can be stressful. Flashing (rubbing on the gravel or rocks) is often attributed to changes in hardness. Personally, I would make any substantial GH adjustment over a period of 2 to 3 days if my aquarium were already stocked with fish.


Rockwork in your aquarium helps with hardness too. While the effects are negligible (except with limestone, which is mostly calcium carbonate and therefore works on GH and KH), total hardness is likely to be higher with rocks in the tank than it would be without. Limestone, Texas Holey Rock (also limestone), pagoda, tufa, lace, petrified wood, quartz, slate, marble, and even common river rock can all be used in your aquarium safely. Be sure to thoroughly clean and sterilize (boil) anything suspect before putting it in your tank.


Hard water can be softened by diluting it with distilled water, but it is rarely necessary to lower GH for an African cichlid aquarium. While researching for this article I spoke with an individual whose water comes from a well and is extremely hard. He dilutes it with both R/O water (reverse osmosis) and water run through a home water softener, just to bring the total hardness down to 40 dH. Apparently his cichlids (both Malawians and Tanganyika’s) are unable to read the test strips because they are doing just fine in both of his aquariums!


Where do I start? The best place to start is with your tap water. Test it, experiment with Epsom salt and baking soda, retest, and determine what ratios are needed to properly condition the water you will add during scheduled water changes. Test your tank water between changes to be sure your measures are sufficient.


NOTE: To test your tap water for pH, de-chlorinate a sample and then circulate/aerate it for at least 60 minutes before testing (overnight would be even better). This will allow any gases to escape that could temporarily lower pH and skew your test results.


Is there anything else I need to add? Aside from products to treat your tap water for toxins (see "Water Treatment") you can provide a fine environment for your African cichlids simply by using Epsom salt and baking soda to obtain pH, GH and KH in the ranges suggested here. Still, some people like to take it a step further and use additives to provide other trace elements found in the Rift Lakes. They believe that creating conditions as natural as possible will result in extraordinarily healthy and colorful fish. Other folks feel that since most of these fish are bred and raised in aquariums, they would not miss the precise chemistry of lake water they have never even been exposed to.


Since beginners are likely to be overwhelmed with the various opinions and products available, here are a few basic options for working with your water chemistry, listed from most economical to least.


Create your own "Rift Lake Buffer/Cichlid Salt" with Epsom salt, baking soda, and salt. You can use aquarium salt or table salt (baseline recommendation is 1 tsp per 5 gallons of water). They are the same thing, sodium chloride(NaCl) except that table salt often contains iodine and anti-caking agents. There are some people that warn against the additives in table salt, but just as many people claim to use it successfully. If this concerns you buy aquarium salt. Sodium and chloride are both found in the Rift Lakes, and salt contributes to the fishes protective slime coating.



Use Epsom salt and baking soda to get the three critical properties within range, and a Rift Lake product (such as Kent Rift Lake Trace Elements®) OR a marine salt (such as Instant Ocean®) to provide additional trace elements. Some people prefer to stick with products specially formulated for the Rift Lakes, while others have had great success with marine salt. Incidentally, I have heard that marine salt is particularly beneficial in planted aquariums.


Go with off-the-shelf products for everything. There are quality products offered by Kent and Seachem (for example) that deal with the basic chemistry, buffering and trace elements. When combined into one product, it is sometimes referred to as cichlid salt. With the information contained herein, you should be able to read the labels on these products and have a better understanding of what they are supposed to do. Test your water to be sure they are living up to their claims.


Other Conditions to Monitor: Be sure that you have a good understanding of the nitrogen cycle. A properly cycled aquarium should test zero for ammonia and nitrites, but nitrates slowly build up in your aquarium and should be monitored. Nitrates are kept in check with regular partial water changes, and are not really so much of a water chemistry issue as a water quality one.


Provide sufficient surface agitation to oxygenate your tank water and allow CO2 to escape.


Maintain a constant temperature in your aquarium. The acceptable range is 74*-81*F, and many experienced hobbyists recommend something in the mid-range, around 76-78*F. High temperatures speed up metabolism and can result in more aggression. Invest in a quality heater to avoid disasters such as overheating or failure. A good thermometer is important too. Do not rely solely on the thermometer on the heater. I look at my thermometer often to be sure the heater is working correctly. By doing so, I once averted potential disaster when an inexpensive heater failed to shut off after the set temperature had been reached. Lastly, be sure to match the tank water temperature when making water changes to avoid stressing your fish.



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