Diamond Brite was applied to our pool in early June, 2015. We added Hayward AquaBrite t-15 salt chlorination system in mid September. Since that time, we've had difficulty keeping the water balanced. I take a sample to our local pool store once a week, and have always needed to add something. There are now stains in various locations on bottom (not sides or steps)of pool. They do not cover the entire bottom, nor are concentrated in any one location. They are light grey. One pool guy suggested they were mineral deposits, and the only way to get rid of them is to drain, then acid wash the pool. The rep from SGM said it was mottling hydration, and that certain products from Jack's Magic would take care of it.
Took a sample of water to Pinch-a-Penny. He suggested using Jack's Stain ID Kit to determine the nature of the stain. But to use Jack's Stain ID Kit, I need to balance the pool to certain levels. One level in particular is troublesome; the TDS. Jack's indicates TDS must be below 1200 ppm. My sample was at 4,500 ppm. Pinch-a-Penny guy said I need to drain almost all the water from the pool, the fill it with fresh water in order to lower the TDS, then use Jack's Stain ID Kit. My question: Must I drain the pool? Is there another less complicated procedure to identify the stain, and then add what I should to eliminate it? Any suggestions would be most welcomed!