Can somebody please tell me if there is a algae called scga algae. My neighbor said he read about it somewhere on the internet. He said it is highly resistant to CL. It mostly gets into small crevices & indentions in vinyl & plaster pools. I do have some type of substance that continually reappears in these places in my vinyl pool. I can brush it away or vacumn it to waste,but it always comes back in the same locations. My water is crystal clear . I have been on BBB since May 2011 with great success. I just can't lick this,whatever, that won't go away. THANKS for any advice. fc 5.0,ph7.7,ta 70, ch 50,cya 40. TFP test kit