While looking in the laundry room cupboard for something to clean black "ring around the pool" in my fiberglass pool, i found my wife's Rejuvenate Tile and Grout Cleaner, which says it is all natural and non-toxic, and uses enzymes to clean. Has anyone tried this in a pool and would it be harmful to the pool or the chemistry? No large amounts would need to be used, just enough to spray the walls.
Heres the product: http://www.rejuvenate.tv/clean_tile_grout.php
Heres the MSDS
I am not affiliated with this product