Palm Fibre Peat fertilized with Chemicult as a substrate for growing aquatic plants

Hi Guys,

There has been a lot of discussion about this topic and I thought it would make it easier for users to download this description so that they do not have to go through the thread on this topic which has got very long.

If you want to comment on what I have written here, add something or ask questions, please give those comments on that thread as I have purposely closed this thread so that it can be used for reference purposes.

Kind regards, Dirk


Palm Fibre Peat fertilized with Chemicult as a capped substrate for growing aquatic plants

Motivation and background

In natural systems in which aquatic plants grow, nutrients are supplied to them via the substrate that they grow in and from the water that surrounds them. This can differ considerably from areas such as the Pantanal in South America in which rooted plants such as Echinodorus (sword plants) grow to Sarawak or Malaysia where rooted species such as Cryptocoryne (crypts) species grow. In the Pantanal the substrate often is iron rich and in Mayasia it is rich in organic components (compost) but also iron rich. In these areas there are also numerous floating plants that do not grow in the substrate that just grow by drawing nutrients from the water alone. If we consider aquatic plants that grow in a substrate, we need to ask which nutrients do these plants draw from the medium itself and which are drawn from the water. It is difficult to separate this. In order to grow, some plants apparently need to obtain their nutrients from the substrate, others can obtain them from the water, but most plants can obtain nutrients from both the substrate and the water column. You may say that they are opportunists and will take fertilizers from either source depending on where they are available.

There are numerous articles about the value of iron in the substrate and the laterite (iron rich) soils which occur in the areas in which these plants grow. As a result, laterite additives are regularly sold as additives for substrates. In the early 1980’s, the company Tetra was the first to promote laterite additives for substrates. Kaspar Horst and Horst Kipper, who worked for Tetra, were the first to initiate these approaches. These authors left Tetra and started their own company, Dupla, which has been a leading figure in aquatic plant growth ever since. However, they firmly established the concept of additional iron fertilization via the substrate medium in which aquatic plants are grown.

From land plants we know that we can feed them by applying fertilizer to the soil. In fertilizers for land plants, nitrogen is added in the form of ammonia, nitrate or urea, phosphorous as phosphate salts, and potassium primarily in combination with nitrate as potassium nitrate. These are the so-called “macro†elements that plants need and are called “macro†elements because large amounts of them are needed by plants. Additionally, we know from land plants that they require certain so-called “micro†elements which are required in smaller amounts as the name indicates, but in spite of the smaller amounts are absolutely essential for plant growth. These include iron (specifically the so-called iron 2+ or Fe2+ form and not the oxidized Fe3+ form which plants cannot use), boron, manganese, zinc, copper, molybdenum and cobalt.

So the debate continues as to whether the fertilizers for aquatic plants can and should be given via the substrate or the water or both. Most specialists acknowledge that fertilization is required both via the substrate and via the water (often referred to as the water column). However, there are different approaches which different authors will support. To complicate this, the amount of light can have a very large effect on how effective the fertilization is. In low light setups, very little fertilization is required as a result of which fertilization via the substrate may be sufficient. Diana Walstad recommends the use of “compost†as a growing medium in “low tech†aquaria in which lower light levels are used. As soon as a higher amount of light is used, the substrate medium will in all likelihood not supply enough fertilizers and an additional amount will have to be supplied via the water column. If you buy an aquarium light from your local pet store, the amount of light that this will emit is in most cases so high that fertilization via the substrate in not enough and additional fertilization via the water column is needed.

This has lead to completely different approaches to aquatic plant fertilization. Initially, it was thought that if you add enough of the micro elements, this would be enough for plants to grow as the macro elements would be supplied by the fishes as a result of converting proteins into nitrate and from phosphorous from the food that fishes are fed. However, it has become apparent that if you use high light, then nitrate, phosphorous and potassium are required and because the substrate cannot supply enough of these macroelements quickly, they must be supplied via the water column. As these nutrients are also not used at the same rate, methods have been developed whereby the micro and macro elements are added regularly at different intervals. Tom Barr and others have developed what is called the Estimative index method whereby those nutrients that are used up are replenished by regular addition of nutrients. In order to compensate for the build up of breakdown products or for shortages in fertilization, this method also uses large weekly water changes and addition of fertilizers at regular intervals which result in excellent plant growth, but is far to labour intensive for most aqaurists. If not correctly balanced though, these methods can also lead to strong algal growth.

In the European and USA products sold for plant feeding, one assumption is made that does not apply to South African conditions, and that is that all tap water contains sufficient amounts of calcium and magnesium as well as carbonate for aquatic plant growth. In South Africa, most areas have water which is very poor in calcium and magnesium, as a matter of fact this is completely absent in areas such as Cape Town. If these levels are not increased, plants will not grow because they need these elements for normal growth. As a result most European and USA aquatic plant fertilizers will not give optimal plant growth in South African tapwater, although there are differences between different areas. In order to compensate for these calcium and magnesium deficiencies, I have developed a fertilizer range for South African water conditions, which have become known as “Dirk’s Secret Drops†or “Dirk se druppels†(DSD).

As a cherry on top, so to speak, the addition of CO2 to the water column will result in even stronger plant growth. This is costly and must be regulated well or else it leads to additional imbalances and algal growth. However, a balance of substrate fertilization, water column fertilization and CO2 fertilization undoubtably results in the best aquatic plant growth possible. However, it must be said that this is a generalization and that many plants do not want the one of other additive and do not want high light, in other words, they require and demand special specific requirements for the best growth for them specifically.

As I have developed my DSD fertilizers for addition to the water column, I asked myself how I could additionally feed plants via the substrate. I have now developed the palm fibre peat fertilized with Chemicult substrate method which I describe after this.

The palm fibre peat fertilized with Chemicult substrate method

Purchase a palm fibre peat brick (the size of a paving brick and shrink wrapped in plastic) and Chemicult Hydroponic Nutrient Solution (supplied in a light blue see through plastic bag) from a garden shop or agricultural co-operative. Palm fibre peat and Chemicult are supplied and distributed in South Africa by Starke Ayres and I see that they give a customer care line on their Palm fibre peat product which is 0860-782753.

In order to prepare the palm fibre peat for use in the aquarium, add one heaped teaspoon per five litres of luke warm water in a bucket and stir it until it dissolves completely. Then add the palm fibre peat brick and leave it at least overnight for the PFP to draw up the Chemicult solution. You will be surprised, but the whole bucket will fill up with this PFP which if you rub it with your hands, you will notice is course medium consisting of particles of about 2-5 mm in size. Cover the bottom of the aquarium with a layer of about 2-3 cm think and press it down firmly with your hand, using less in the front of the aquarium and more at the back (any of this PFP that you have left can be mixed with sand and you can use it to plant your pot plants in). I have found that the addition of normal iron nails which will rust can be beneficial and these can be placed into the PFP. Use 2-3 cm nails or panel pins at distances of about 3 cms between them. This is however not essential. This will lead to an additional supply of iron from the substrate similar to laterite soils.

Next you need to cover this PFP with gravel, or cap it as it is called. I prefer to use fine filter sand, but any aquarium gravel will work. The thickness of the gravel should be a minimum of 2 cm deep. It is easier to plant aquatic plants into this medium when the aquarium does not contain water. After planting the plants, water must be filled into the aquarium very carefully so that the water does not wash open the PFP. Plants can also be planted when the aquarium has been filled with water but the aquarium must have been filled with water for at least two to three days before you do this or else the PFP will float out of the substrate onto the water surface and cause a mess. When planting in a filled aquarium, care must then be taken not to release too much of the PFP, but after planting any PFP that floats above the medium can be removed by syphoning it off.

It is very important to note that the Chemicult will feed the plants via the medium, but that this is not enough in my opinion. Additional fertilization via the water column is essential and I recommend the use of my DSD fertilizers to be used in addition to this medium.

Palm fibre peat as a substrate

Why use palm fibre peat (PFP) as a substrate additive? The most important factor that I considered was cost. Substrates such as Excel flourite are sold at very high prices in South Africa and are way beyond the reach of the average aquarist. Sera florodepot and a similar product from Tetra are aimed at a combination of laterite and macro and microelement additions via the substrate but are also not cheap. Palm fibre peat is cheap (approximately R25 per brick) and reasonably accessible in South Africa. The consistency of PFP which is constant independently of where you buy it in South Africa was also a very important consideration. The components of Chemicult are not expensive and are also consistently the same.

There have been reports in local forums of persons using "rose compost" as an additive to their substrates. These persons also capped this compost, but then complained about algal growth and smells. I also experimented with garden composts and rose composts. What I find very worrying about "rose compost" or any other nursery compost is that there is no consistency in the use of what goes into these composts, some have chicken manure added, others contain pine park, and so it carries on. In my opinion, this is a ticket for disaster, chicken manure is rich in ammonia and has high levels of bacteria and bark contains high levels of unsuitable and plant unfriendly tannins. Mineralized soil is also often suggested and used as a substrate. Here again it depends on the soil that you start with as to how successful this will be, but again there are vast differences between different soils and I feel that this is a serious problem in the use of mineralized soil. I felt that I wanted to use a medium that was going to be constant and that I could recommend to someone elsewhere where he could buy it off the shelf and have the same thing. Palm fibre peat is such a product. It is compacted coconut husk that has been ground to particle sizes of about 3-5 mm. Chemically it contains cellulose and lignin (both are important components of wood) and are chemically INACTIVE, which is very important. It will also only decompose very slowly (I am talking in terms of 2 to 3 years) and will not release all sorts of undefined nasties with time. I have used this medium extensively for my above water potted plants with excellent results for many years. Then I have also experimented with it in aquaria and it works very well. What is particularly heartening is that the root development in this medium is excellent. I have tried composts and they go anaerobic (blocked without oxygen) because the decomposition uses up all the oxygen and these media stink when you dismantle the aquarium. In contrast, palm fibre peat stays perfectly in shape for periods of two to three years, does not rot and hence the roots are fine and there is strong root growth, indicating healthy plants. Then I want to add that plants that require feeding from the medium such as crypts and many other plants such a Limnophila aromatica, various Rotalas which are chronically difficult plant to grow, thrive in this medium if you use my aquatic ferts added to the water in combination with the palm fibre peat.

Why use Chemicult as a fertilizer in the palm fibre peat?

The Chemicult for hydroponics fertilizer contains a balanced mixture of macro and microelements which in my opinion is suitable for aquatic plant growth. It has a ratio of N:K of 3:1:5 and contains trace elements. One must remember that in normal garden fertilizers a significant proportion of the N is in ammonia form which is toxic for fishes. When used in hydroponics this would cause problems if this was too high so it is purposely lower and is therefore more suited for use in aquariums. I would for example not recommend the use of the chemicult for orchid feeding in spring, the so-called 30:10:10 mix, as this contains far too much N and by implication ammonia and no trace elements. What I do want to emphasize immediately, is that Chemicult as an additive to the water of an aquarium for plant feeding cannot be recommended because of the ammonia, it will kill your fishes as you will get an ammonia spike. If it is added to the substrate, it will largely remain there and can be used by the plants, but it will not leach into the water quickly and not cause the problems of ammonia toxicity. This is very important and ANYONE THAT USES CHEMICULT FOR AQUATIC PLANT FEEDING WILL BE DOING SO AT THEIR OWN RISK, I ADVISE STRONGLY AGAINST USING IT, and will not take any responsibility for fish losses if anyone does use it.

Disadvantages of this method

Palm fibre peat does contain humic acids. Humic acids have long been discussed as additives to the water for sensitive fishes such as discus and for fishes coming from the Amazon River in South America. However, humic acids are anti-bacterial and anti-algal so there are lots of advantages, but humic acids give the water a brown colour which some aquarists do not like. If you have the feeling that you want to remove the brown color but do not feel like water changes, you can filter the water over activated charcoal, it will remove these substances. You must just remember that you must remove the activated charcoal within a week from your filter or the activated charcoal will start releasing the humic acids again after a while. Alternatively, you must remember that you need to fertilize your plants as well and in order to do that properly, you must actually do water changes as well. So, you could combine the water changes with fertilizer additions. Then, if you have a lot of money you could also use Purigen, but in my opinion it is absurdly expensive and for this reason is just simply not justified, in my opinion, then I would prefer the brown color of the water or do water changes!

Another disadvantage of this method is that you cannot use it if you are keeping fishes that burrow into the substrate. Heavy catfishes that dig into the medium will soon cause the PFP to drift all over the tank so they cannot be kept in such a tank. Corydoras catfishes can be kept in such a tank as they do not burrow as strongly. My opinion is that heavy catfishes often damage plants in any case and therefore do not have a place in a planted aquarium as a result of which they should not be kept there in the first place.

So, in my opinion, the disadvantages of this method are not serious and the advantages far outweigh the disadvantages. I hope this advice will help you understand why I am using it and why others are starting to use it as well now to achieve excellent aquatic plant growth.