Very interesting thread. This is my first year with a SWG (installed in June '06), and I live in the Northeast. The pool is a vinyl liner, 20x40, around 20 years old. CYA around 45. No special features. Over the past 2 years the only thing I have used to raise pH is borax. My pH has been between 7.2 and 7.4 all summer. Total acid added - zero! Contributing factors may include lots of acid rain, and my use of a solar cover when the pool is not in use. I have added virtually no fill water all year.