I have brown staining above the water line. I tested it with vitamin c, which lightened it a bit, but did not remove it- I made a loose slurry of crushed ascorbic acid vitamin c, sponged it on a test area and lightly scrubbed for about 3 minutes. It did not respond to a household cleaner test patch and it does not feel as though there is any build up of any kind.
Thoughts?
Thoughts?