I have a 6600 gal fiberglass pool with a SWG. My pH tends to stablize at 7.8. When it creeps above I add about 3 cups (24 oz.) of acid and my ph is just below 7.4. It then gradually creeps up to 7.6 over the next two or three weeks and then stays there for another 2 or 3 weeks. As long as it is staying in range of 7.2 to 7.8 I don't worry about it too much. I have used Borax in my poos so the borate/boric acid buffer system will stabilize the pH a bit higher than a bicarbonate/carbonic acid buffer system alone will.