Thanks to all for teaching me all I do know about my pool. It has been neglected for years. I've gone from 0 FC, high PH, no calcium, scale on the walls, plus green algae and what I think might be black algae. I do have the black circles on the walls but I also have this tar-like stuff in two dead corners, under the ladder, and also in the seams between the wall and the approximate 8" ledge around my big old pool. We have a SWG that just died. We learned it wasn't enough for our 63,000 gal pool and have decided to forget having a SWG and just do chlorine. I hope to get to bleach ASAP.
The good news is I heavy trichlor shocked for about a five days, scrubbed the algae, and I think I'm about balanced. I'm scrubbing the circles with a puck and scrubbing the tar areas with a wire brush. I've left a puck on the tar stuff and can't really tell if it is doing anything. I think digging and scraping it off is all that has really helped. My pool water is sparkling and crystal clear.
I'm just looking for advice about what that tar stuff might be and should I just keep scrubbing until there's nothing left but concrete. It must have eaten the paint. I hesitate to shock again because the water seems so perfect. I am keeping the chlorine (trichlor) high. I've got a fountain going for aeration and just installed a Pool Skim which is a wonderful little jewel. I'm not running the skimmers because I'm still trying to keep the level below the skimmer to patch a leak at the skimmer face plate. Am running the main drain. Like the guy at Leslie's said, there is a lot going on in that pool.
Any advice would be appreciated. I am sincerely trying...