I have a 20K gallon negative edge pool. I can't seem to control what appears to me to be calcium deposits on the pool plaster. To me they look a lot like efflorescence. The pool is a SWG with ozonator. It is blue-black colored plaster (looks blue). The white calcium can be sanded off, although the plaster seems to become white and discolored with the calcium deposits (so in many spots it looks like the calcium deposit is there even though the plaster is smooth to the touch).
First of all, I've had a horrible frustration with pool store results. I've had instances where I've taken pool water to three different pool stores within a few minutes and gotten completely different results. So now I have two home test kits. One is a Blue Devil kit and one is the TF-100 kit recommended here. I did multiple tests with both home kits and there is no way the calcium is less than 190.
Pool Store Results: 4.0 CL, 7.6 PH, 145 CH, 100 TA, 45ppm CYA, Salt 3000, total dissolved solids 1200.
TF-100 Results: 4.0 CL, 7.8 PH, 200 CH, 90 TA, 45 CYA, Salt 3000
BD Results: 40 CL, 7.8 PH, 200-250 CH (test is by 50s), 90 TA, 45 CYA
Jandy SWG recommended ranges: 1-3 CL; 7.2 - 7.8 PH; 150-400 CH; 80-120 TA; 50-75 CYA (75-85 summertime); 3000-3500 salt.
The precipitate happens very quickly. If I sand off all the spots one week, I could have more precipitate by the following week. Sometimes my PH gets a little higher than it should, but usually I try to keep it in the 7.4 range (Jandy manual says 7.8 is a natural level for SWG).
I also have to say that I've suspected that my calcium is higher than what the stores have been telling me. Often the stores would test at less than 400 but my Blue Devil kit tested much higher (TF-100 just came this week). I should also add that I suspected hard water at the house as contributing to problem as my faucets all get a white ring around the base and the shower heads have white crust too. My pool line has a calcim ring, although it doesn't come off without an acid solution and much scrubbing (it doesn't fizz). This summer we had a lot of rain, which I believe lowered the calcium levels.
Anyways, I'd like to keep my calcium levels low as I think they could rise up. If my home test is reliable, I want to stay with that level. But whom do I trust? The store or the