I'm getting ready to close up our pool in the next week or two and was re-reading PS and noticed that it said adding a polyquat algaecide was optional. I was just wondering how many people actually use it and does it make that much difference one way or the other. We've had a sparkling pool all summer thanks to TFP and BBB, so I definately want to continue to follow the recommendations of fellow TFP'ers. Thanks!