we have NEVER drained any of our pools. In the winter, we have the pool co. maintain the chemicals weekly, and we run it for a few hours a day. On the really cold nights, we run it to keep it circulating. I would not drain it, because water left standing in the pipes would be a BIGGER problem when it all freezes.
Do call a reputable company, of course.
K
ps. in the summer, it is circulating probably 12 hours a day. In the winter, maybe 5-6 hours a day. Or less.
ps. i would assume it is a 'gunite' pool- over cement. We don't have a cover on ours.