I've got a situation that I can't figure out. This is my first summer with a pool and using the TFPC method. So far I've been able to keep my pH consistent for the last couple months with little maintenance. It always slowing drops and I add borax from time to time to raise it, it's never gone high until now. I tested yesterday and today and my pH was 8.2, before that it was always around 7.6. I do not have any aerators on/in the pool. We've had an excess of rain the last couple days but I thought that was supposed to lower the pH. What could have caused it to rise so quickly?
Current results taken this morning
FC - 11 (raised it to clean my solar cover)
CC - 0
pH - 8.2
TA - 90
CYA - 60