I had a stain issue with my pool light last spring when I used a non stainless screw that rusted. I replaced the light and did an AA treatment. It lightened the big stain but several other smaller stains came up. Not wanting to spend the money on chemicals to do another I decided to live with it. Over the summer we have been getting what looks like dirt buildup (brown film) on the steps and sides near the bottom. This has been getting much worse as of late and big dark spots are forming. Here is a picture
I have been keeping my levels in range all summer and CC has been 0 or less than 0.5. Tests this morning show
FC 5 (before adding chlorine today)
pH 7.9 (this has been creeping up. Added 20 oz of MA to get it back down to 7.6)
I tried scrubbing them with no luck. After scrubbing them I placed a sock of Ascorbic acid in one area and a triclor tab on another. After 30 minutes there was no change to the area with the triclor but the AA was noticeably better. The brown film was gone all around the sock and the dark sports much smaller but still noticeable.
I think I have narrowed it down to metals but I don't know where to go from there.