I've had my pool now for 4 years. We had a warmer than usual winter, and I did not maintain chemical levels as maybe I should have. Because I had black algae that developed, I super-shocked my pool with the initial application of 5 gals. of chlorine, and applied 1 gal. per day for 3 days, subsequently. I got rid of the black algae, but I have these sand colored stains that are appearing on my pebbletec. It's random, but it appears more in the more shallow areas of the pool.
It is a salt system pool, and I have a DE filtering system if that is of any help. Also, the pool is 25,000 gals in size, and is a 3' to 5' to 4' deep pool.
Any advice would be welcome.