We have a new pool with spa and I'm having trouble at times with the spa plaster (Diamond Brite) getting a rough, sort of sandy texture to it. It rubs/brushes off, but comes back in about a week. It seems to be when the PH gets high, and I add acis to get PH back down. The pool finish does not have this problem, and the water circulates between pool/spa.
Is this likely caused by chemical imbalance? if so, which reading (PH, chlorine, etc) is they key to watch closely?
Thanks for any input/suggestions.