I have an above ground pool with a saltwater chlorine generator. The ph and chlorine levels have always been really easy to maintain with this system. I think I still may have some type of algae though. It is this brown "stuff" on the bottom. After you vacuum it up, it takes about 3-4 days before it starts reappearing. I have even "hyper" chlorinated a few times just to see if that would make a difference. It has not done anything, other than give me a bright yellow solution with my test kit for a few days, lol. Any ideas on what it could be or how to get rid of it? Oh yeah, if you leave it in there for more than a day or two, it gets harder to remove. It almost acts like it stains the liner.