Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
When I had a lot of livestock in my tanks I dosed very little KNO3.
I used K2SO4 as the K source.
As noted above, if you are dosing the full recommended amount of KNO3 per EI methods, then that should be enough K. If not, add a little K2SO4.
The amount of K from KH2PO4 is so low it pretty much does not count.