pH stays between 5.5-6.0 constantly. only have to fiddle with it about twice a week. as far as i can tell, the only thing i'm battling right now is the yellowing and humidity. the problem with my basement is that it has a curtain drain, and we have had tons of rain the past couple weeks and the rain water flows around the curtain drain in the basement. my guess is that's the main problem and there's nothing at all i can do about that.