I thought I had metal stains so ordered and now have 3 lbs of Ascorbic. I did the sock test today before trying the AA treatment and the stain got darker underneath the sock after a minute soak. I was using a dark pair of hose to start with so switched to a white sock thinking the color in the hose was transferring. Got the same result. I also tried hitting it with some muratic acid through a plastic pipe. Held it over a spot for a minute or so with no visible change.
I don't have any pucks so have not tried that.
My question is what gets darker when you put AA on it? Here's some pictures. Most all of these dark stains are on the bottom of the pool with very few stains on any vertical surfaces.
CH 160 need to get this up