Have been doing BBB for 3 years (bought my first place with a pool and found this forum-thank you very much), so the water is always clear, no algea or other problems. But I can't keep the ph stable. I have to put in a 4lb box of Borax every week. Is this exessive? Here are the facts:
25,000 vinyl in-ground, solar cover on most of the time (when I'm at work)
CYA 30
FC 3 - 5 ppm (I check and adjust daily, don't let it drop below 3)
pool temp 78 (it's been warm this week - had been around 74 for the past month or so)
ph 7.2 (I'll put in a 4 lb box and it will go up to 7.6, but will drift down within a week) I don't let it go down below 7.2 but I can't get it to stay up. We've had no rain so why won't it stay?