[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Aquatic Plants Digest V3 #602

Hello Tom,

I don't think that there is a person alive, that can tell you, without
any contradictions, what the optimum N-P-K ratio is!

But since you are planning to experiment, here are the N & P ratios of
some of the phosphates you are interested in:

(NH4)H2(PO4)  N = 12.18%,  P = 26.93%

(NH4)2H(PO4)   N = 21.21%,  P = 23.48%

K2HPO4   K = 44.89%,   P = 17.79%

KH2PO4   K = 28.73%,   P = 22.76%

Ca(H2PO4)2  (superphosphate)  P = 26.47%

CaHPO4    P = 22.77%

Ca3(PO4)2  P = 19.97

Hope that these numbers will help in your experimentation!



> Date: Sun, 25 Oct 1998 14:12:59 EST
> From: TomWood3 at aol_com
> Subject: 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.
> Thanks
> Tom