I use reverse osmosis (RO) water with a ph of 7 and 0 ppm
I have never thought of the ph being a factor, but maybe I am wrong on that.
Also, the
Forbid 4F is made and sold by a company that sells the same product under a different name (I think it is named Judo?) and it is approved for food goods up until one week before harvest. But I would not recommend using it in flower anyway.