Last week I noticed what appeared to be black dirt on the bottom of the pool. But it would not vacuum or brush away. Upon closer inspection, It appeared to be little spots of (what I'll call) algae. It was very dark green, almost black. And they were in small craters in the diamond brite all over the pool. I tested the water, and found that my SWG was dirty and had not been producing chlorine, I was at 0 chlorine. The pool store told me it was black algae. I got the SWG working and boosted for 48 hrs, got it up to a 5 where it has been for a few days. Continuing to scrub with a metal brush, but they are stubborn.

Now they have diminished by half, but they are still there. Was told to add black algaecide (from leslie's). Added the recommended amount, but still no change. Is this really algae? The diamond brite is not even a year old (done last July) and now it has all these small craters. Any ideas or suggestions would be great.

THanks