30+ yrs old gunnite/plaster pool, 35,000 gal inground, sand filter. Painted with epoxy 15-20 yrs ago, then again with acrylic 10-12 yrs ago. Old finish stripped off & replaced with mono-epoxy last year. Finish was fine for western Washington 2010 pool season. Due to long, crappy winter/spring, didn't open pool until mid-May. When we did, we found some paint chalking. PH at opening was about 7.0, Alk was 95, Cal was 30, TC was 5(test kit is Poolsolutions PS233). Added borax & baking soda so far, rasied PH to 7.2 & Alk to 130. Any advice as to how to proceed to prevent future paint chalking? Thanks.

Dan