You still will need to maintain the chlorine at the higher level with the higher CYA--but you'll find that as the water temp drops, so will the rate at which your chlorine does. I keep my pool open year round but during the summer I add the large jug of WalMart bleach 3-4 times a week, but once the water temp gets below 60 or so, I only have to add it 1-2 times a week to keep the chlorine in the recommended range.

Janet