Our pool was filled in late May, and the PB noticed blotchiness in the pebble finish so he drained the pool and performed an acid wash. The finish was perfect for a short time, but by the end of June it was blotchy again. The PB and the finish manufacturer's rep have identified the problem as scale. The pH was consistently over 8.0 and the CH in the 550 - 650 range, both of which have prevented the beginning of treatment with Jack's Magic #2. We've since gotten the pH down to 7.4, but the CH is stubborn and hasn't been lowered despite multiple attempts. The incoming water is 70 ppm calcium, so the source isn't the water we don't think. Plus, it poured down rain all last night (over 2 inches) and the CH is still 550 today. Is it possible that calcium leaching from the pebble finish is causing the CH and scale problems?