Since the pool was opened this season there has been a ring/ stain around the main drain. I have scrubed it with a brush from outside the pool and vaccuumed and the stain is still there. There was a lot of dead worms around the main drain when I opened the pool this year so I assume that it is from them laying around the drain all winter.
What can I try to use to get rid of the stain?
What can I try to use to get rid of the stain?