1. Other manufacturers recommend a different iron content?

Yes, we noticed that too!

This applies both to the instructions of the aquatic plant fertilizers and sometimes also to recommendations in the relevant iron test sets.

However, there is a good reason why we generally recommend a lower iron content

  • The half-life of iron (and other minerals, for which iron is measured in a representative capacity as it is the easiest to detect) depends on various factors in the aquarium.
  • It is a property of high-quality fertilizer products, like those of our company, to have as long a half-life as possible.
  • At the end of the recommended dosage period, iron must still be detectable, because gaps in supply may lead to growth stagnation. The longer the recommended period is, the greater the initial concentration must be.
  • A long half-life is achieved by using high quality (and expensive) chelators and at least the molar amount of chelators.
  • Simpler (and cheaper) products which for cost reasons do not involve these chemical-technical measures have a correspondingly shorter half-life (service life) in the aquarium.
  • However, a shorter service life requires a higher initial value to guarantee a corresponding iron content at all times.

As an excessive iron content greatly encourages the growth of certain algae (such as brush algae) but minimal quantities of iron are sufficient for tall plants, it is advisable to achieve a lowest possible but even iron content.
Iron content which fluctuates greatly over the course of a week is also not ideal for excellent plant growth.

This can be supported by the regular addition of a high quality aquarium plant fertilizer (such as Ferrdrakon or KramerDrak) or with an ideal dosage system (Ferrdrakon Evolution).

2. The fertilizer turns black!

The colour of the fertilizer has changed. It now looks almost black!

  • Is this normal?
  • Has it gone bad?
  • Does it still have the required properties?
  • Why is that?

Yes, this is normal and does not impair the effect of the fertilizer.

A small quantity of iron(II) ions of the fertilizer oxidises to iron(III) due to the oxygen in air. Iron(III) ions and their complexes are generally coloured much more than Fe(II) ions.
The complex of preservatives and trivalent iron is very intensively coloured and leads to this brown-black solution.

3. The colour of the self-mixed solution

This applies to the coloured solutions KramerDrak, Ferrdrakon, Ferrdrakon K and Daydrakon.

You have just made the fertilizer solution from the refill powder according to the instructions.
However, the colour of the solution is much lighter than the ready-made solution previously purchased and you ask yourself:

Have I received too little powder or the wrong powder?

To make a stable, non-caking or perishable refill powder, it is necessary in some cases to use different chemicals for ready-made solutions (however, the specified and guaranteed active agents are always contained in the same quantities).

The pH value of the self-made solutions may therefore be slightly different, and the solutions hardly had time to absorb oxygen from the environment, for example, when freshly mixed.

For this reason, the solutions freshly made from the refill powders are at first very light in colour, but they darken slightly over time, even if they do not usually become as dark as the ready-made solutions.

4. Mixing and diluting?

  • I would like to add the fertilizers with a dosage pump. For this I have to mix the various solutions. Is this possible?
  • The smallest quantity which the dosage pump can dispense is too large. Can I dilute the fertilizers to achieve practicable dosage volumes?
  • What can I use for dilution?

Daydrakon, Ferrdrakon (K) and KramerDrak can be mixed in any proportion.

It is not recommended to mix with Eudrakon P or Eudrakon N.
In the first case, insoluble phosphates can be formed, in the second the urea contained can be decomposed with a heavy metal catalyst.
If it is nevertheless necessary to mix, you must carry out your own tests with regard to service life.

The fertilizers can also be diluted. However, as the preservative is not diluted but its effect depends to a great extent on the concentration, only the quantities should be diluted which are intended for immediate use.
The solutions should be stored in a place protected from direct light, which applies to an even greater extent to diluted solutions.

Tap water, reverse osmosis water or demineralised water are suitable. If the tap water is very hard, reverse osmosis water or demineralised water should be used if possible. This water should be free of germs as far as possible due to the diluted preservative, therefore please do not use aquarium water or similar.

5. Phosphate consumption too high?

I started to increase the PO₄ content with Eudrakon P. Already the next day, or even after a few hours, there is no trace of phosphate any more although I added the recommended amount!
  • In particular in tanks which were very short of phosphate for a long time, the consumption is in some cases enormous. The plants fill up their reservoirs, but every surface in the aquarium binds PO₄ by absorption (including the filter content, panes and floor) too. This may mean that after a very short time no more PO₄ is measurable.
    Normally after a maximum of 2 - 3 weeks, the reservoirs of the plants are full and all surfaces are saturated. Now the phosphate requirement should decrease to the current consumption of the plants (normally only a fraction of the initial requirement).
  • We recommend not adding anything. This is a common misunderstanding.
    The instruction only describes the quantity required to increase the PO₄ content by a certain amount in a certain quantity of water. This is not connected with any information on consumption. This can generally not be predicted and is therefore to be determined for each tank by the owner by recording the quantity added and the difference between the theoretically calculated and actually measured phosphate content over several days. If this difference is divided by the number of days of the observation period, this gives the current daily PO₄ consumption.

6. Adding fertilizer in the morning or in the evening?

It is not possible to answer this question due to a lack of information. No scientific studies have been carried out so far.

As many people only add fertilizer to their aquariums once a week and this generally works well, the fertilizer is not completely used up within 24 hours or does not spoil even if added daily, the time of daily addition of fertilizer is actually completely irrelevant.
To maintain a certain routine and not become confused, I would recommend always adding fertilizer at the same time.

7. Shipping in winter

Tolerate the liquid fertilizer also frost as it may be the case during shipping in winter?

Yes, it can easily happen that the fertilizer arrives frozen occasionally. No reason to worry.
Please let the fertilizer thaw completely and shake it thoroughly several times. Then it is immediately ready for use. The quality does not suffer.

8. How long can the fertilizer powder be kept?

The combination of chelator with EDTA structure and iron salt is sensitive to light not only in solution but also in form (even if considerably less so). The energy consumption through light absorption destroys the EDTA structure with a loss of chelator properties (this process is known as photochemical decarboxylation).

In short, the powder must always be protected from light and also from moisture, so that it does not cause problems due to caking when dissolved later.

If stored in such a way, the fertilization powders can be kept for many years.

Slight caking and a change in colour of the fertilizer powder is not a sign of spoilage but a completely normal ageing process of the mixture, so to speak, which has no influence on the later effect of the solution.

9. How long can the fertilizer solutions be kept?

Ferrdrakon, Ferrdrakon K, KramerDrak and Daydrakon can be kept unopened for at least 3 years after production*.
Eudrakon N resp. P can be kept unopened almost indefinitely, Eudrakon P also when opened.

After opening, the solutions should be used up within six to nine months if possible (exception Eudrakon P). If possible, please buy containers which you can use up within this time. If this is not possible, fill your daily requirement in smaller containers and open the storage container as infrequently as possible.

A darkening in the colour of the solutions and even blackening is not a sign of spoilage but a normal ageing process of the solutions and has no influence on the effect of the compounds.

The combination of chelator with EDTA structure and iron salt is sensitive to light. The energy consumption through light absorption destroys the EDTA structure with a loss of chelator properties (this process is known as photochemical decarboxylation).

*Stored correctly, i.e. as dark as possible and at room temperature or cooler.

The new plastic labels contain a unique serial number. With this serial number you can find the relevant use-by dates of every individual bottle in this form.

10. How can one dissolve the refill packages best?

Please follow the linked guide!

11. How much does a portion of fertilizer powder weigh?

There is no need to be over-accurate when portioning, as 10 % more or less does not matter. The dosage of fertilizer must subsequently be adapted to individual pool sizes anyway.

The quantities given are also not to be considered as absolutely unalterable. Depending on the chemicals currently used (e.g. water content), changes are always possible.

Fertilizer portion for 0.5 l 1.0 l 3.0 l 5.0 l
Production as of 05/22 with IDHA
7.8 g
8.9 g
15.5 g
17.8 g
46.5 g
53.5 g
77.5 g
89.2 g
Production as of 11/21 with IDHA
13.9 g
14.6 g
27.8 g
29.2 g
83.4 g
87.6 g
139.1 g
146.0 g
Ferrdrakon BIO 21.1 g 42.2 g 126.6 g 210.9 g
Ferrdrakon K
Production as of 02/22 with IDHA
74.8 g
75.6 g
149.5 g
151.1 g
448.5 g
453.3 g
747.5 g
755.5 g
Production as of 09/21 with IDHA
50.2 g
50.6 g
100.3 g
101.2 g
300.9 g
303.7 g
501.5 g
506.2 g

Warning: In this form, the chemical used are irritating and partially harmful to health. When processing these chemicals, please wear appropriate protective clothing such as gloves, dust masks and protective goggles.

12. Invertebrates and copper?

Daydrakon, Ferrdrakon, Ferrdrakon K and KramerDrak contain copper. This is very toxic for invertebrates.
Can Daydrakon, Ferrdrakon, Ferrdrakon K and KramerDrak be used in pools with invertebrates?

Copper is the emotive term which causes alarm among all invertebrate owners!

Daydrakon, Ferrdrakon, Ferrdrakon K and KramerDrak contain a lot of other toxic heavy metals including iron, manganese, nickel, cobalt, zinc and molybdenum.

Seriously, copper is a trace element which is just as essential for invertebrates as it is for other animals (not to mention for plants). In this case, the dose determines where it is beneficial and necessary or excessive and damaging (the same applies to the other metals listed). The values achievable via fertilization with Daydrakon, Ferrdrakon (K) and KramerDrak are 1,000 times below toxic concentrations. In addition, they are all used as chelatic forms, the toxicity of which is normally 100 times lower than that of the free Ions.
So theoretically, the absolute all-clear can be given. Many decapods have even a copper-based blood pigment (Hemocyanin).

Practical experience: We keep shrimps, crabs and snails in fertilized pools with plants, others who use Daydrakon, Ferrdrakon (K) and KramerDrak also do this without any irregularities becoming apparent.