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?

Also, forgot to ask? What is the best whole house water softening method? I am thinking that her source water is an issue, because there are mineral buildups in plumbing and dishes, etc. She has that magnetic thing, which I told her is worthless. What would you recommend as a replacement that actually works?

It probably is scale; the rougher texture on the tile and scale on the faucets/dishes are a dead giveaway. Diluted muriatic acid in a spray bottle will take care of the scale on the tiles, just lower the water level a little, spray, and scrub with a plastic brush.

A standard water softener is really the way to go.

I agree with MITS and you both. It is surely calcium scale and likely the source water is the issue. You must be able to test CH, pH and TA to get a handle on it and to take any permanent corrective action.

You should probably also tell your friend thay HAVE to get involved and learn to test themselves to get this resolved effectively.

(PS - I'll be in College Station on the 29th to watch the Aggies play Missouri.....my son is at A&M in the corps)