Having some problems with check valves.. my system has zero check valves in the main plumbing and what happens at night is the 3/8" push connect checkvales i have on the filter side (pressure) side just don't work well and lets the liquidator and ph adjustor drain out, eventually to air and so slowly over night gets air in the line from that point in the pipe down to the pool. luckily not enough to break prime on the pump or filter (filter does get some air in it). Anyways, I've tried replacing them and about the same thing.. my only thought is the new ones (same part) from mcmaster listed for "horizontal install" .. I have them dangling diagonally in the air. Another thing is the flow meters get air in them and have a hard time clearing the air out daily.
Despite all that, the pool is doing ok.. Acid was doing great until i realized it had burned through 5lbs of acid in a week and a half and was basically out... reloaded and turned the valve open a bit more and ph is coming down now.. so it's good to know i can adjust level vs just maintain. Chlorine is doing ok.. I would like to keep it at 4PPM but it seems like it is having trouble maintaining that.. or at least hasn't yet (we are in week 2 of messing around).. I haven't yet just run it full open to see what happens.. think i'm going to do that today / check it tomorrow.