I have been having a problem with a predominately black with a little bit of green build up around the inside of my skimmers. Assuming this is algae. I don't have it anywhere else except a little bit on the rail of my auto cover. Pool water is clear. Balancing is good except this year my free chlorine has been tough to keep consistent. I've used a lot of tablets. I have been using a sponge to clean my skimmers but I'm getting tired of doing it everyday. Does anyone know what,where why and how I can solve this problem.
both skimmers get it & one is worse than the other
5 year old pool