nkk329951701

We have some nasty stains at the bottom of our above ground swimming pool, I talked to Pinch-a-penny and they told me that all my levels were great and to dump 6 1/2 gallons of chlorine in the pool well the stains lifted but two days later they came right back, the color of them are light brownish/blackish color. They said that black algae can't grow in above ground pools. So I just don't know what it is...