So, about 3 years ago, I screwed up and refilled in ground unite pool from the wrong hose ...yeah, the one not connected to the water treatment system that remove iron and metals ...pretty quickly got an iron waterline stain.
I used ascorbic acid ...got it in 2 pound bags ...still seemed expensive, but way less so than buying s "special" product. It pulled most of the stain off the wall, but I still have some staining ...a bit less each year, I guess as the water ratio has changed as I have not reintroduced any untreated well water.
Given where I am, how best to continue to work on the staining? More ascorbic acid? Is there a special device that one can load ascorbic acid into and scrub the line?
Thanks and happy pool season to everyone!