I have a 16x32 Vinyl pool approx 18000 Gallon Salt Generator. When i opened the pool it had dirt a leaves at bottom and pool was green shock and filtering cleared the pool up in a couple of days. But I have blackish green stain all a\the bottom 1.5 foot of the wall of the pool completly the floor is not stained at all. When i put a vitimin c tablet on it it did nothing but with a piece of chlorine it worked. What suggestion to get rid of the stain.
An additional problem I have is High hardness level I dropped 50% of the pool and it is still high any suggestions.