I have a friend who lives in a resort community in Baja CA, Mexico. Its a very small pool, probably less than 4K gals. The pool surface is not plaster. According to my friend, it's a mix of cement and sand, kind of a cheap PebbleTec replacement. The tile work is small glass tiles, about 1 inch square. She is having trouble with the tiles getting what looks like calcium deposition or a scale on the tile. In areas where there is evaporation, the glass tile is rough. There is no white crusty material, just a rougher texture on the tile. Where there is no evaporation, the tile is still smooth.
She does not have the right test kit yet. She will likely get one of the better test kits sold on this site. The Cl is fine, TA is 190, pH is 8.0, also high. I cannot check CH or CYA. It is not an SWG pool, and it uses a DE filter.
I am aware of the CSI, but cannot check that without the right test kit. But, IF the problem is Calcium, what corrective measures are usually prescribed? I see that the CSI test involves many factors, so that we might fix this problem by adjusting any one of them accordingly. Also, given this unique "surface", what choice should I use in Pool Calculator?