The bleach did lighten the green stain, but not much. also once i saw the stain lighten i put enough bleach to make 8ppm in my pool with 20 cya and brushed the stains but they didnt go away. what is my next step? and how do i get rid of the stains completely? also there one spot in the pool maybe 1foot by 6inches that is slighty off color greyish, not green. and it wont brush off or lighten with bleach or trichlor on it, any ideas? thanks for the help.