We have a 24K gallon in ground pool (gunnite). It's about 8 years old and was totally drained, acid washed, and refilled this year due to staining (which really looked like plaster hydration!). The plaster is in good shape, the pool sits in full sun, and the water temperature often is quite warm (93° today). We have to add about a gallon of muriatic acid a week to keep the pH at 7.2-7.5. For example, today we are at free Cl of 3.6, pH of 8.0, alkalinity of 140 ppm, hardness of 250 ppm, CYA of 80 and a saturation index of 0.8. We have no water features. First question is why the pH constantly drifts up? I can only imagine that adding this much acid over the summer isn't going to be a good thing. Would addition of borates help stabilize the situation, or make it harder to bring the pH into range? BTW: had the same balance issues before draining. Using a Taylor 2006 test kit. TIA!
