I leave my pool open for the winter, just for the appearance. We won't swim again until probalby May here in central NC. I've not added any chems since the fall. When the water temp was in the 50's or 60's I got some green algae that is still there. It comes off the liner easily (where the Polaris works the most, it's clean), but it's more stubborn on the plastic steps and the Polaris exterior. Water temp is now at 39. To get rid of the green, should I add bleach or an algaecide? pH is 7.8, TA is 70. If bleach, what chlorine level is needed? CYA is probably about 80.