Good point about nutes. If you make up a tub of feed water, your best adding the nutes before getting your ph right. I use Biobizz nutes aswell and they lowered the ph as Plainjane says. I still had to add a tiny amount of phosphoric acid (ph down) as my tap water is about 7.5. I tried cider vinegar at first but strange things happened. It would lower the ph, but as the days went by the ph value of my solution began to creep up again until it was back where I started. That was only with cider vinegar tho. Dunno why. Phosphoric acid worked fine though.