how can I remove gray stains above water line on fiberglass pool?
Answers:
Go to your local home center plumbing department and get something for removing minerals. Wet the area with a sponge and go back and gently rub. Be careful not to scratch with something abrasive. That will just create scratches in the fiberglass that will fill with deposits and make future cleaning more difficult.
Other answers:
Use the "fantastic" spray cleaner and a sponge
Use the "fantastic" spray cleaner and a sponge
We use "Greased Lightning" and the coarse side of a dish washing sponge.
I don't mix it with any water. Spray it directly on the stains wait a few seconds & wipe off.
Try bleach full strength or something like lime away or CLR
mr clean magic eraser.
Damon industries makes a industrial strength cleaner called SF-77, it's like $12.00/GA. If that doesn't do it, nothing will. Damon ind. is based out of ohio