I got in the pool out back, a process taking approximately 13.79 hours of inching down the steps, and I swam the length of the pool a few times. My lips are still blue from the cold. I am convinced that persons who enjoy swimming have actually undergone a secret medical procedure whereby all sensations of temperature are permanently blocked. Gotta say, though: my feet don't hurt while I'm in there. (Not that I can feel anything at all while I'm in there.)
Re: You didn't ask for MAS but...
We've got a heater for it but it's expensive enough that we don't run it. We might look into other ways.