Split off to it's own topic. Thanks JasonLion
Not to hijack the post, but my marble spillway where the spa goes over into the pool is rough like sandpaper - no visible bumps, but just feels rough. The PB is claiming it must be calcium scale (although he has not seen it). I know they just went to Home Depot and got a cheap piece of marble for the spillway because they cracked the original one and I think it is just being eaten away by the salt and chemicals.
So how can I determine if it is calcium scale? Wouldn't it be on the tile and plaster too? My pH has never been more than 7.8 for more than a day or two at a time. CH was high (400) for a bit but has come down to 370 after a few heavy rains.
How do you get rid of calcium buildup on plaster?