dantaylornz

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May 3, 2022
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I have done a bit of reading recently about DIY micro mixes and potential issues with CSM+B and EDTA. I live in New Zealand and have previously imported CSM+B for use in my 300 litre (~75 gallon) dutch style aquarium. However, I have moderately hard tap water (8.1pH, 9dKH and GH of 13ppm) and have always been concerned about issues with EDTA given that with CO2 injection the lowest my pH reaches is ~6.8.

I currently dose my own macro mix based on EI and also dose DTPA Fe 11% but I have been inspired by @burr740 to eliminate CSM+B and replace with my own mix. I'm trying to get all of the ingredients together locally - the main issue is obtaining them in lower quantities. I have a couple of questions though:

1) Plantex CSM+B has EDTA chelated Cu, Mn, Zn, and FE. I will use DTPA Fe in my mix, but what about the others? I note that @burr740 uses non-chelated salts and I recall reading somewhere that @Tom Barr suggested that it wasn't particularly advantageous to use chelated micros for anything other than Fe? Could someone kindly clear this up for me and explain why you might or might not use other chelated salts in a bit more detail?

2) I note that @burr740 includes NiSO4.6H2O in his custom mix (see forum post here), but I don't see this in CSM+B and the other trace mixes I have compared either. It doesn't look like @burr740 is visiting this forum any more but I am hoping someone might be able to enlighten me on the benefits of including nickel?
 

Allwissend

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Hellow and welcome dantaylornz,

I'm not Burr but hope this helps. The main reason people use strong chelators for iron is because iron will easily oxidize in most aquarium setups. Other micronutrients are not so prone to this, especially at low pH values. EDTA chelation will still help in keeping other micronutrients in the water column and thus available for plant uptake for a longer time, but are typically more expensive than simple salts.

In fertilizer solutions with high concentrations of micronutrients and PO4 (such as All in ones, hydroponic fertilizers) chelation of all micronutrients is preferred as it will limit the interaction between the nutrients. Micronutrients meant for agriculture are also likely be chelated to maintain their availability in soil ( varied pH, very high conc. of many other ions).As we have flexibility to make our own individual solutions and our aquariums don't have high concentrations I think and seen both work with similar results at high and low KH/pH.

The main role of nickel is a an essential cofactor for urease, the enzyme that degrades urea to CO2 and ammonia. It is came into discussion in the context of people dosing urea and using RODI water. Rigorous research in the aquarium context to see the benefit of adding it and in what quantities is missing. Probably because the nickel amounts actually needed are very very low and appear to be provided by the impurities in things like fish food, substrate, tap water etc.
 

dantaylornz

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May 3, 2022
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Thanks for your fast reply @Allwissend. A couple of further questions:

In fertilizer solutions with high concentrations of micronutrients and PO4 (such as All in ones, hydroponic fertilizers) chelation of all micronutrients is preferred as it will limit the interaction between the nutrients. Micronutrients meant for agriculture are also likely be chelated to maintain their availability in soil ( varied pH, very high conc. of many other ions).As we have flexibility to make our own individual solutions and our aquariums don't have high concentrations I think and seen both work with similar results at high and low KH/pH.

If I have the option of using chelated salts for the minerals other than Fe, should I? Or are you suggesting there is unlikely to be an advantage in the planted tank?

The main role of nickel is a an essential cofactor for urease, the enzyme that degrades urea to CO2 and ammonia. It is came into discussion in the context of people dosing urea and using RODI water. Rigorous research in the aquarium context to see the benefit of adding it and in what quantities is missing. Probably because the nickel amounts actually needed are very very low and appear to be provided by the impurities in things like fish food, substrate, tap water etc.

So the summary is that benefit of using nickel at this point is not clear but in such a low quantities there is no harm in including it?
 

Allwissend

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If they are available and cost appropriate for you then use chelated traces. Apart from those listed above, I consider the advantages in most high-tech planted tanks to be minimal.

Probably no harm if included in quantities even lower than Molybdenum.