My pH is, at the moment around 7.4. I am dosing soda ash at night for about ten minutes. It raised it somewhat (it was at 7.08). What's crazy is that I have lots of surface agitation, lots of tumbling water, not a lot of teenagers breathing in the house. I haven't checked Alk yet, this has just been on for the last two nights. How quickly can you raise the pH? I haven't tried fresh air into the skimmer but the skimmer is in the basement so maybe not a lot of fresh air going in there during the winter. IN addition, I have been wrestling with my system for the last year, it almost completely crashed. All the sand has been replaced and a lot has been cleaned out. Now I just have this last piece left -- chronically low pH.