how much potassium is in my water? - Fertilizing

alexanderM · 09-27-2005, 04:06 PM

Okay, if I were to use KNO3, KH2PO4 and K2SO4 to mix SS, NF, & PF solutions, we can test for NO3 and PO4 but how do I know how much (K) im adding to my water? What if I don’t want to mix a standard solution (SS) and would rather dose NO3 individually? I can use the Nitrate Free (NF) solution for phosphate and potassium but if I dose KNO3 for nitrate, there is that issue of the K sitting in front. Can someone point me to a source that will give me the ratio of potassium to nitrate in KNO3? I would rather dose nitrate individually because my current bioload keeps NO3 levels between 5 and 10 ppm with weekly water changes and want to dose just enough to keep it at 10 ppm.

Just out of curiosity, what is the ratio of potassium to phosphate in KH2PO4?

Many thanks to whoever can enlighten me.

brad · 09-27-2005, 06:06 PM

p04 Phosphate 69.8% KH2 30.2%

**czado** · 09-27-2005, 11:11 PM

Removing H2 from *brad's post, K is 28.7% of KH2PO4
KNO3 is 38.7% K.

Don't worry too much about K+. Some don't dose K2SO4 at all, knowing they reach good K levels from KNO3 dosing. A little excess won't break anything.

plantbrain · 09-28-2005, 11:34 AM

A lot excess will not break anything either.
Eg 50-100ppm ranges.
10-50ppm is a decent range and should be easy enough to target.

Regards,
Tom Barr