Npk Dosing

[Underwurlde]

Hello,

I am slowly getting my Engineering type head around NPK dosing for EI....

Everyone is steered to using this excellent calculator when figuring out dosing levels:
http/www.csd.net/~cgadd/aqua/art_plant_dosage_calc.htm

The calculator asks (among other things):
Nitrate in Potassium Nitrate (I get that)
Potassium in Potassium Nitrate (I get that too)
Phosphate in KH2PO4...

Now, KH2PO4 is Potassium Phosphate, right?

sooooo...

Why is the option for 'Potassium in KH2PO4' not included in this calculator?

Surely dosing with KH2PO4 will dose the tank with Phospahte AND Potassium...
(Is this why the calculator calls it by it's chemical symbol KH2PO4 instead of just saying 'Potassium Phospahte' I wonder, to stop people like me wondering about this..... )



Andy

 

[Themuleous]

Not sure why it doesn't include it, but generally speaking adding both potassium nitrate and potassium phosphate provides the tank with enough potassium so generally you dont need to know how much of it your adding as adding the right amount for nitrate and phosphate gives you the right level of potassium.

So just dose the nitrogen and phosphate to the right levels and that should be fine. Your plants will tell you if they are not getting enough potassium.

Sam

 

[Underwurlde]

Ah, I see, that makes sense.

Thanks.

 

[Underwurlde]

Got there in the end:

70% Phosphate in KH2PO4
30% Potassium in KH2PO4

So, YES I think adding KH2PO4 will ALSO significantly dose up levels of K as well.
(Therefore still wondering why it is not an option in the calculator. Then again I'm no chemist and this is all just guess work & speculation so anyone reading this, this should NOT be taken as FACT unless otherwise confirmed by someone with an education ).

Andy

 

[George Farmer]

KH2PO4 is dosed in small qtys. to reach desired levels of PO4, therefore the K would be negligable.

 

[Underwurlde]

Ah, gotcha!