There's a problem in my new-ish pool. Hasn't been a year yet, and I've been having great luck with the TFP method. And my chemistry is just right. This morning FC 4.0, CC 0.5, pH 7.5.
So, there's this thick black grease on the tile all along the waterline, like a dirty bathtub ring. I can scrub it off with a scouring pad but it just re-deposits, and it doesn't wash off the scouring pad in the washing machine, either. I suspected the motor for the pool cover, but I called the company for service and they took a look and it wasn't throwing out any grease (and was greased with clean white lithium grease). Then I tried to convince myself that it wasn't actually grease, but algae -- it isn't. It is dirty thick grease. Not sunscreen or hair conditioner, but some kind of petroleum. So where could this be coming from, and why? The pool doesn't get heavy use, just me swimming every day and a few friends on the weekends. The pool cover guys tried to tell me to get some "oil be gone" product at the LPS but of course I'm not going for that, as I want to figure it out.
Another issue, the very expensive pool cover has a single line of algae on the bottom, in a fold (about 1 inch by 4 feet) that has never relaxed. The pool cover guys say they've never seen anything like it, but of course in the inside of the fold does not touch the water to kill the algae, and the cover is a bit translucent, as you can see the pool light through it if you forget to turn it off at night. I've tried weighting the crease down with wet rugs, and walking on it, but it has never relaxes for good. Pushing it down does get the algae wet and kills it and causes pieces of it to fall into the water, but I need to convince the cover guys to get the crease out of there for good. Anyone had a similar problem?
Many thanks for all your help.