Multi-Component Fertilizing For Better Results

Posted by on Sep 6, 2011 in All Categories, Aquarium Maintenance | 0 comments

Multi-Component Fertilizing For Better Results

With 30 years of aquarium experience I am a dinosaur. This is true for both my occupation with the hobby and most of my beliefs and general practice. If, like me, you have believed for a long time, that  nitrate and phosphate are banned substances in an aquarium, it is quite a change of paradigm if you start pouring them into your tanks.

But first things first. Like most aquarists, I have struggled with algae for years. Even if I was able to combat the symptoms by introducing shrimp and other little helpers, the cause for the algae, i.e. stunted plants, was not always fully remedied. I kept wondering what was wrong in my thinking as I was using the top brands in fertilizers, kept to a regular regime of water changes, supplied enough CO2 and provided ample light. Still, some plants refused to grow as I had expected them to with all that goodness I supplied.

Using single- or two-component fertilizers did not allow for a controlled enough supply of nutrients.

Only when in recent years there was more and more talk of macro-nutrient fertilizers and “Esimative Index” fertilizing became popular, did I understand that macro-nutrients had played a far too minor role in my own aquaria. I also understood from following discussions in specialized aquarium plant forums such as UKAPS or Flowgrow, that a much more carefully targeted fertilizing scheme was needed if certain deficiencies were to be remedied. Partly, this meant I could not carry on using single- or two-component fertilizers as those would not allow for a controlled supply of individual nutrients. But at the same time it meant that I had to start understanding deficiency symptoms better.

For my testing purposes I decided to use “Aqua Rebell” component fertilizers. Their product portfolio is very comprehensive and even has different nutrients available in a range of mixtures and, more importantly, chelations. Mildly chelated fertilizers are more readily available to plants but will also oxidise more rapidly. The opposite is true for more strongly chelated components. What I liked most about Aqua Rebell was their complete openness and the fact that they declare the formula on each product. On their products you don’t find vague promises such as “Lush Plant Growth” or similar claims. Instead, it is pointed out that dosages need to be adjusted for each aquarium individually.

Promises such as  “Lush Growth” and other frequently heard claims for aquatic fertilizers achieve nothing and irritate in cases of non-success.

Since I wanted maximum growth, I decided to go for the “Estimative Index” method, whereby plants are given at least the maximum dose of each nutrient. This means that sometimes, even some slight over-dosing may occur. To avoid unpleasant side effects such as as build-up of nutrients, a 50% water change is recommended each week. Especially phosphate, erstwhile the acknowledged arch enemy and algae-promoter, is supplied in abundance. Other macro-nutrients such as Nitrate and Potassium are also added liberally. A balanced supply of micro-nutrients is also administered to create a full range of elements.

The Aqua Rebell range has a special compound for EI fertilisation, Makro Basic – Estimative Index. It contains a higher proportion of Phosphate than the NPK fertilizer. Additionally, I bring in a trace element compound, Aqua Rebell Mikro Spezial Flowgrow. Using one or more components has been common practice for a while, the reason being that mixing certain nutrients will result in compounds that are insoluble in water and thus inaccessible to aquarium plants. As an example, phosphate and bivalent iron will readily form iron-phosphate. It has to be said that the same will happen in  the aquarium, so both components need to be topped up on a regular basis.

Evaluation of The Situation

The state of the plants before the switch

Albeit most of my plants in my test tanks (a Dutch style tank and a discus tank) were growing well and there was not a huge amount of algae growth, there was some scope for improvement. Some plants had signs of stunted or at least slow growth. Even if this may be true for most aquaria, it is not a common thing to be seen in professional tanks. On the contrary: Most of the contest winning tanks display strong and very vigorous plants.

Furthermore, some crippling of shoots was evident (Alternanthera reinecki, Rotala macrandra “Green”). Some plants did not grow at all (Ludwigia inclinata var. verticillata “Curly”) or suffered from stem-rot (Myriophyllum aquaticum) and, consequently, had to be replanted regularly. The Lilaeopsis brasiliensis in the foreground had developed some black, bristly algae.

Changing a running system can yield unexpected results so the first measure was to document the status quo. After all, you never know if you are in for some nasty algae growth, dissolving plants or other vexations. First, an account of problematic plants:

Obviously, not all plants were growing poorly. Hygrophila pinnatifida had thick, upright shoots and its leaves were huge. A clump of Blyxa japonica was growing very steadily and Hydrocotyle tripartita had formed a nice and dense mat in the foreground. Floscopa scandens was bright green and without even a trace of algae growth and a newly planted Ottelia ulvaefolia had been growing at a steady one-leaf-every-two-days pace.


Summary of results

Results upfront: After two weeks I saw a literal explosion of growth unlike anything I had seen so far. Both the average leaf size and overall gain was clearly noticeable. Some (but not all) of the plants which had been wasting away before started to grow nicely now. Only one plant did not respond well to the new fertilising but I’ll get to that in a minute.

As mentioned, I decided to go for the EI method of fertilising. However, since I wanted to use maximum light intensity on my Dutch Tank for extra-compact growth, the Aqua Rebell guys were very helpful in advising me to use a Nitrogen-enriched fertilising regime. Translated to my 450 liter Dutch tank:

  • Aqua Rebell Makro Spezial N: 230 ml per week
  • Aqua Rebell Makro Basic Estimative Index: 115 ml per week
  • Aqua Rebell Mikro Spezial Flowgrow: 63 ml per week

My discus tank got blessed with a new fertilising program also. I keep some of the plants in both tanks and I was interested in how the Aqua Rebell fertilisers would lend themselves to being used in both types of tanks. Nitrogen is present in copious amounts in the discus tank so I did not need to add any extra. 15 g of beef heart twice a day for the fish is quickly metabolized into inorganic nitrate by the filter. Hence I fertilize thus:

  • Aqua Rebell Makro Basic Phosphat: 75 ml per week (Su, Mo, Tue, each @ 25 ml)
  • Aqua Rebell Makro Basic Kalium: 25 ml pro Woche (once on Sunday)
  • Mikro-Basic Eisen Volldünger: 140 ml pro Woche (daily)

For this tank, dosage is carried out manually since I am using mostly old equipment here.

The most obvious results:

Limnophila spec. Vietnam:

Limnophila spec. ''Vietnam''

Limnophila spec. ''Vietnam''

This plant used to be a poor grower but has now formed a nice little stand in the mid-ground of my discus tank. The plants are soft and supple and cuttings can be taken easily for replanting. One of the reasons this plant has failed in my Dutch tank seemed to be foraging by some of the inhabitants (can’t say which) but due to the new, accelerated growth, the plant seemed to have been enabled to outgrow the grazing. Like most Limnophilas, it seems to do well in warmer conditions.

Ludwigia inclinata var. verticillata “Curly”:

Ludwigia inclinata var. verticilata ''Curly''

Ludwigia inclinata var. verticilata ''Curly''

This used to be a tough one: no growth or hardly any more than what was dying off. Since EI I see steady new growth and a healthy appearance. Unfortunately, I completely missed taking some photos of the black, decaying tips before EI.

Myriophyllum aquaticum:

Myriophyllum aquaticum

Myriophyllum aquaticum

Concerning the Myrio, I’m sure it must be the increased amount of light I’m using now: Before EI, I had illuminated my tank with only 80% (check out the article on my small tank). With the new fertilizing method, I have switched to 100% without getting yellowed leaves or plants that tried to grow faster than they could be fed.

Alternanthera reineckii:

Alternanthera reineckii

Alternanthera reineckii

Leaves are now deep red and there is no new stunted growth any more. Most of the shoots have already recovered totally.

Limnophila aromaticoides:

Limnophila aromaticoides

Limnophila aromaticoides

This plant has lost its crippled tips but is still smaller than its counterpart in the discus tank. I attribute this to the fact that this plant is warmth-loving. In the discus tank it is rampant now with nice and lush growth. Its gain so strong that it needs trimming once a week now.

Hydrotriche hottoniiflora:

Hydrotriche hottoniiflora

Hydrotriche hottoniiflora

I don’t even plant it properly now – it is just weighed down with some foam and lead. All its nutrients come from the water column.

Other plants have profited from the new fertilization as well: The Fissidens had to be trimmed quite radically and Lilaeopsis is growing faster and seems to out-compete the algae much better now. another piece of evidence supporting my hypothesis of a correlation between plant growth and algae infestation.

So – is everything better than before? Overwhelmingly, yes. With one exception: Hygrophila pinnatifida seems to be losing its leaves in the lower nodes now. The leaves have turned pale showing little holes in the leaves proper. After talking to some people about this, I think I have an idea what causes this:  Because of the higher feed of nitrogen into the water, another element might have got into short supply. A quick calculation revealed that it was probably potassium but it remains to be seen if this educated guess was right. Fortunately, Potassium is available as a single component from Aqua Rebell. I will report any changes in the Hygrophila as soon as I see clearer.

There are some plants which showed no reaction at all. Rotala macrandra “Green” still has crippled shoots but with overall faster growth than before. I tend to think that this may have a non-chemical cause, such as redox potential or something else entirely. I will observe and report should I see the light here…

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