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Type of iron chelate in Tropica fertilizer


New Member
6 May 2020
Markham, Ontario, Canada
I had signs of iron deficiency and I reviewed the recent thread on types of iron used such as EDDHA, gluconate and DTPA.

In my 40 gallon breeder I was dosing 3mL of Tropica Specialized per day. I added 1mL of Tropica Premium and a whole bunch of 11% DTPA (1/64 tsp per week, split into daily doses, mixed into distilled water for convenience). This resolved some iron deficiency symptoms I was seeing.

I think that the reason that iron became an issue first, rather than something else, might be that the type of iron in the Tropica fertilizers is better at low pH and not so effective at higher pH. My tank water is 7.4-7.6 pH when ungassed (down to 6.6-6.8 pH during the lighting period via CO2 injection). It has kH 3 and GH 7.

You can say that I'm a beginner as it's only my second time with a high energy tank. Essentially my experience was that I felt I was working towards a low light version of EI in order to prevent any nutrient deficiencies (at least in areas of the tank with great circulation). Then I learned it's not so simple when it comes to iron. Taking the iron content in the fertilizer itself for your calculations may not be enough, since depending on the type of iron, not all of this content may be usable at higher pH levels.

Just looking here for confirmation, others experiences, and perhaps a weigh-in from Tropica on whether perhaps some sort of a guideline could be developed for new users with higher pH, and/or whether Tropica could disclose the mixture of types of chelators used so that people can better predict results and better relate results to others. Even for beginners, some additional direction about iron seems to be needed, but perhaps only for some of us: those with high pH.
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