Let me know if I'm crazy. There are a couple of reasons why I would like to leave my pool open through the winter. First, I have planned on using my auto cover as the winter cover. The pool has a raised wall on one end, and an elevated portion on the opposite end, so installing a typical winter cover would have been difficult. Second, we want to entertain around our deck/patio area year round, so being able to open the pool sometimes & see the water is nice (instead of an ugly winter cover stretched over the pool & pool deck).
BUT, I live in St. Louis. Our winters are very unpredictable. It is possible to get below zero (F) temps for brief periods (last winter's "polar vortex" gave us one day with a low of -11 F). Typically, though, we'll only have a few days per winter in the teens. We get snow a few times per year - usually a couple of inches, but with 8-12 inch dumps possible. The snow usually melts within a week or so.
My Intelliflo pump has a freeze protection feature. My Easytouch system also can be configured to turn up the pumps with below freezing air temps. I don't mind firing up the heater now & then to get the water temp up a few degrees if necessary. The Easytouch makes all of this simple - I can do it remotely with the Pentair app on my phone or computer.
Obviously, I don't want to risk major damage to my pool structure, plumbing or equipment. My water line tiles are 1" glass. With the auto cover, I can't drop the water level below the tile line or skimmers - it will no longer float on the water surface. My equipment (pump, filter, heater) are not enclosed - they are on an exposed concrete pad on the far side of the pool, away from my house.
What should I do? How much water movement would I need through the pumps when the air temp is near zero (I have several options with the Intelliflo pump, and can keep the power usage fairly low with lower RPMs)? How devastating would a "worst case scenario" be if I lost power for a few hours with frigid temperatures?