We finished and filled our pool in mid October 2011 and haven't been doing much except maintaining the pH and chlorine. It seems almost to be too simple. I have been adding acid about every three days to keep the pH down and it seems like no matter how much chlorine I add, it hardly even shows anything on the test. How important is chlorine in the winter? I don't want to waste money on something that isn't needed. We have used the spa 3 times since we filled it and the pool once for about 20 minutes. Right now the water temps are about 45 degrees so I wasn't even sure if I would need chlorine since it is so cold. Once the water warms back up above 50 deg I am going to add salt and get the chlorine generator going, but for now we have just been adding liquid chlorine.