Hi,

I have a 16 X 32 AG vinyl Doughboy. Last winter I closed with shock & Polyquat. This spring I opened to pea soup. Once I got the water cleaned up and sparkling I could see a brownish greenish stain from where the winter water line was down to the wall/bottom angle.

I converted to the BBB method this year and spent the first 2-3 weeks in shock mode trying to see if it would bleach it away in case it was algae residue. Didn't phase it. I've tried brushing, using a scrubbie, etc., but nothing takes it off. It's below the water line so using anything on the sponge just washes away as soon as I dunk it in.

Over the summer I <think> that it has faded a little. It's more mottled in appearance than it was initially. It even might have disappeared from the top of the stain line down a couple of inches.

I use Ben's kit and, once I got the chems balanced, have been able to keep the water sparkling and clean.

I have read many posts that talk of Vit C, Jack's stuff, etc., but haven't seen anything related to under water stains in a vinyl liner.

I saw some that related to metal in the water but I don't have any way of testing for that and haven't seen any metal testing equipment in local pool stores.

I do have a heater but didn't run it at all last year. I have used it this last month or so.

I'm getting ready to close for the season (live in western PA. It was 40 degrees last night) so am wondering what I can do so that it doesn't get worse over the winter.

Any help gratefully appreciated.

CoffeeBean