ok what i mean is can you mix
N-P-Ks

12-12-12 + 9-9-9 = 21-21-21

i would image that if you were to you would have to use double the water instead of one gallon use 2 then add each and should be fine. Just trying o figure out a way to get all trace elements along with secondary and the macros.
without having to wait before each feeding. Spent a load of money on my new box and just about broke. So can't afford more nutes at the moment.