I have a number of brown stains on my pool that I thought were the result of me letting the chlorine getting too low, pH too high, and leaves and tree berries getting in the pool when I first moved into the house. Chlorine pucks would not touch these stains. Lowering pH and SLAMing didn't do anything either. If I put Ascorbic Acid tablets on the stains, and let the tablets fully dissolve, the stain will be gone or nearly so (may take another treatment). I also noticed that the area around where I put these tablets, the blue plaster is bluer. I had the water tested for iron and copper at the pool store, and both came up zero.
Today I decided to tackle the bigger stains at the deep end. I put two tablets on the larger stains. Sure enough, they are dissolving, and you can see a brown water trail from each stain. Further out from the stain, the plaster is turning bright blue (about a foot).
There are no stains on the sides of the pool, only the bottom.
So I'm confused, are these organic stains that just take some extra acid to dissolve, or iron stains?