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Chemists - Need Advice Please

I am currently using the PMDD method with some success.  As you probably know,
this entails dosing K2SO4 and KNO3 along with a trace element mix.  I'd like
to experiment with additions of these and some form of phosphate in the
substrate.  I note that the Jobe's fern sticks have a 16-2-6 N-P-K ratio and
that the analysis says the nitrogen is N, the phosphate is P2O5, and the
potassium is K2O.

I have a hydroponics catalogue that provides phosphate in several forms - Di-
Ammonium Phosphate (NH4)2HPO4, Di-Potassium Phosphate K2HPO4, Mono-Ammonium
Phosphate NH4H2PO4, Mono-Calcium Phosphate Ca(H2PO4)2+H2O, Mono-Potassium
Phosphate KH2PO4, and Triple Superphosphate CaH4(PO4)2.

Whew.  So, the question is - What form of the above phosphates would work well
with K2SO4 and KNO3 and in what ratio should all three be mixed to provide an
optimum N-P-K ratio for aquatic plants?  Am I right in assuming that each of
these compounds disintegrate into the required N-P-K elements according to
some chemical reactions that can be calculated? To make the calculation
easier, assume no inputs from the other sources in the tank.