I have an indoor aquatic physical therapy pool, 10,300 gallons (3 1/2' to 4' deep). We opened on July 11 in Homer, AK. The pool walls are 100% small glass tiles with epoxy grout. My CH is around 360 and TA around 80. 12.5% liquid chlorine. I try to keep the pH at 7.5 but it does creep up on me so I periodically add dry acid. Using the pool math calculator, my CSI comes out to around +0.26, which is within the OK range, but I do get calcium on the dark blue tiles above the waterline. I've read that the high-side CSI limit is around +.3, so I am pushing on that. My question has to do with how to lower the CSI into a slightly negative value but still within the OK range, maybe around -0.1 to -0.2. Will make the water less likely to deposit white stuff on the tiles? I also get white residue on my blue pool cover. I am thinking about draining off 1-1/2' or 2' of water and filling it back up with clear water to lower the CH, then balance out the other values. Does anyone think that making the water slightly acidic and less calcium rich will have any adverse effects? I believe that epoxy grout is pretty resistant to slight acidity. BTW, I have no windows in the pool room so I don't use CYA. The pool consumes about 11 oz. liquid chlorine daily, so a 15 gallon drum lasts about 4 months. The chlorine is fed with a Stenner pump/tank combo.