How can you remove the brown stains on the bottom of a gunnite pool from chlorine tablets?

Some pool stores sell a tool just for small stains. It may have to be ordered. I think it is made by Pool Tool in Ventura, Calif. It uses a small amount of acid in a cup like device which is placed over the stain. Caution: leaving the device on a spot too long will etch the plaster and it will be worse than when you started. Tablets are not thrown into the pool to maintain chlorine levels. Use a feeder. Also do not put tabs in the skimmer.

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