Interesting discussion - I will try to collect a rain sample in a clean cup and test the pH. In two and a half months, my pH has not moved up at all with bleach in fact it seems to creep down (usually around 7.3). I have not added any water to the pool in this time but I have had to drain water out at least 4 different times because of all the rain this year.

I've been using about a 3qt container of 6% bleach every two days and my alk was 90 the last time I checked it in a 13500 gal AG pool.

Peter