First time grower uk

Right the story so far we’ll the kids were doing well A is doing very well lots of buds stacking up B on the other hand not so good. Basically the water wasn’t getting to the bottom and sitting on the top soil so a carefully burrowed some holes in the soil and there now picking up.
The PH is hi tho the soil reading is 4.4 and my feed is 4.3PH witch is 10L water 40% coca A&B so now the combined PH is 8.7 and I’m thinking does this need to be brought down to a combined 6/7PH