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Macro/micro dosing


4 Jun 2009
West Sussex
Hi, Could someone explain the reasons for dosing NPK and micros on different days please? :?
No real big reason. Some find it easier to dose on alternate days and sometimes the iron in the micros can react with the phosphate in the macros creating a white haze to the water. This haze can also happen if dosing on alternate days as well to a lesser extent.

Blooming heck, thanks guys. I now have to decide which way to do it. :)
I do not think it makes any difference.

My tank water is loaded with PO4 no matter which day are Traces added, so...........

This I think is some hold over from an old myth perhaps.
Or maybe someone made a new one up? :silent:

Anyway, do not add them together in the dosing bottles, do not worry about them in the tank, I add them the same day and at the same time without issues for 2 decades.

Tom Barr
They use an ion fixer I believe, the iron/copper etc reacts more readily with the fixer than the ferts so forms bonds that would other wise be formed with the po4 etc. Then once it's in the water it breaks down and releases the part that's usable to the plants.
That's only an assumtion though my science is limited.
Hi all,
Out of interest, can someone remind me how Tropica manage to include Fe and PO4 in one bottle (Tropica Plant Nutrition+) without precipitation/clouding?
Probably using EDTA. Iron (Fe) is the most strongly chelated element, so it won't be "dislodged" by any other element. It only becomes available when the Fe EDTA is photo-degraded (which is why you need to keep FeEDTA in a dark glass bottle), so there are no free Fe ions to react and form insoluble iron phosphate compounds.

The order of binding, from least strongly held to most strongly held metal ion is, Na, K, Mg, Ca, Mn, Cu, Zn and finally iron Fe3+ (it's a log scale and Fe is most strongly held by a substantial amount).

cheers Darrel