I don't close mine and I am in Northern CA. Last winter I was able to reduce pump time to 2 hours (normally 6 hours in summer) and chlorinator down to about .5 ppm. The water temp got down below 50 at one point but never below 45 degrees. I did continue to use vacuum since that is a high leaf drop time for us. This winter, I may just use a leaf rake since the leaf basket would fill every day anyway.