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[APD] RE: K+ from KNO3

> Looking at a mass balance of N/K+ ratios, __most/many__ plants have about
> 1.5 :1 ratios of N:K(Epstien 1972).
> So you should theoretically have 3x as much K as you need relative to N x
> the 1.5/1 ratio = 4.5x as much K+ relative to N per dose.

Some error but not enough to matter here: 


39.1g K+/ 101.1g KNO3= ~.39
14 g N/ 101.1 gKNO3 = ~.14

.39/.14= ~2.79 K+'s for each N added using KNO3.
Taking into account to plant's dry weight mass %'s.

1.5 x 2.79 =  about 4.2:1

The ratio is 4.5 vs 4.2. Some error there FYI. 

> There are other sources of N, plant decomposition, fish waste but some K+
> comes from these pools also.
> I really do doubt that adding K2SO4 to such a tank will make any
> significant difference.

There's some error here , not precise measurements, but it's still puts the
K+ relative to N way over the needs of plants if you use KNO3 as a main
nitrogen supply.
I think it would be tough to run out of K+(have become limiting) unless you
had a large fish load, very low light etc.

So we may not need to recommend adding K2SO4, KCl at all in many cases.

Cool, we only need to add 3 things besides light and CO2 for even a high
light nicely done CO2 planted tank(assuming the GH/KH are fine).

Not bad. If you have enough PO4 in the tap, then only two things.


Tom Barr



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