Try algecide gel and a soft sponge. You might also try Vitamin C tablets in a sock.
There are a number of ways you could remove stains from worms on a vinyl liner. You could use cleaners.
One pound of ascorbic acid per 10,000 gallons.
You can't
i stored a vinyl hot tub in storage and now it has yellow and black mold stains on it. how do i remove the stains and smell?
yu lift it up
muriatic acid should work fairly well
Many things can cause iron stains on the vinyl siding of a home. The best way to remove these stains is to use tub and tile cleaner and a cloth scouring pad.
I've used Goo Gone to remove stains from vinyl bags before. I would test it on an inconspicuous area first to make sure it doesn't harm the finish. I used it mostly to remove surface stains and dirt, so if your stain is deep into the vinyl it might not work as well.
Milton ... the cure all for impossible stains and marks
no on paint! You will need to replace the liner.
You could try spraying straight bleach from a spray bottle, and then rinse with either reverse-osmosis or distilled water.
Afraid not. Vinyl liner pools are built using "concrete receptor coping" into which the deck is poured. It also contains the "bead receptor" that the vinyl liner attaches to. Actually YES it can. You would want to do this during a liner replacement but it can be done. You would have to remove the concrete from around the perimeter of the pool, remove/ replace the "concrete receptor coping" with bead receiver, aluminum extrusion, form/pour a bond beam, then lay your stone. Not really an easy do it yourself job but it can be done.