I mix a standard EI macro mix 500ml.
Also a bottle of each = to Flourish N &P 250ml.
If I need to go light on PO4 I dose less EI mix and add a splash of N.
But it's all up to you!
I am guilty of testing water about every ten days for N & P
Thanks, once you understand this stuff it makes sense finally!!
One more question: I have an old batch of Mac mix in a 500mil bottle that I was using when I was dosing the PPS PRO method. I know I can add more N and PO4 to reach the proper dosing amounts to reach the correct ppm. But in this mix I also have K2SO4 and MgSO4
There's 29 grams K2SO4 -20 grams of MgSO4
I'm dosing 15mil at a time so that would be 2.6ppm K and 0.3944ppm Mg I don't know if my tap water is low in magnesium as far as the MgSO4 goes so I don't know if that would be a problem? And the extra K I see that some people add extra any way.
So, in conclusion would it be ok to use the old batch?