I would like to add a question. We have a 38000 gal. gunnite pool. We chlorinate with 3 inch tabs and shock with calcium hypochlorite. For years we had a problem with high alkalinity levels (200+), this year however that is not a problem (102), but we are having problems with our pH. Our Cl levels have stayed around 2ppm all summer, but we can not get or keep the pH above
7.0. Early in the season we were running around 7.1-7.2, but in June it dropped to around 6.8-6.9. We have put a lot of Borax (3.5 boxes) in the pool over the course of the season with little change. As I mentioned earlier our usual problem is Alk. not pH. Any suggestions would be welcome. We bought some soda the other day, but would rather not use it because of past issues with high alkalinity levels.

The pool is crysal clear with no algae problem, but the pH issue concerns us because of possible damage to our heat pump pool heater.