what nutes are u using? I have it down to a science with Latewoods GH schedule and by using RO water and the recommended 8ml/gal pretty muck brings it to 5.8, it raises a hair the next day and then 1.5 ml of down per 2gal levels it out till the next change/1wk. Water temp may become problematic. optimal, 65-68 deg. If you are using hard water, it is hard to stabilize. Be careful of using too much down, it can flocculate with calcium and make some shitty gypsum in ur tank.