what's this on the bottom of my pool

Jan 7, 2013
hi all, please have a look at the link showing the bottom of my pool. My pool water is balanced, new filter with new sand. I'm not sure what this is, it feels a little grainy when i touch it, it disappears if i spread it. Vacuuming it doesn't help for long. I don't think it's algae, i've super chlorinated the pool thinking it was, comes back.




LifeTime Supporter
Sep 23, 2013
Dallas-Ft. Worth Metroplex, TX
Are those pool store test results? You should get yourself a good test kit and do your testing yourself. Those pool store tests are frequently inaccurate. We can't advise you on what to add without knowing the source and strength of your chlorine, but I can definitely tell you that your FC is low based on your CYA. If you do in fact have algae you need to follow the SLAM instructions step by step, not just throw a huge quantity of chlorine in the pool one time and hope for the best. :D