Can I leave my pump and waterfall running thru the winter.

[Catch&Release]

I'm going for it. Because the pond has a skimmer the pump is probably only 15" or so below depth. I've hung a sump pump in front of the skimmer to keep the water flowing and I have that short piece of hose hanging in the garage should I need to top it off. I've been using a sump pump for years just to keep the surface from freezing and I don't believe I've ever had a problem. It agitates the water enough to oxygenate it or at least I hope so. I would love to heat the water enough so the pond never froze but that would cost as much as it does to heat a jacuzzi and who does that for more than a few billing periods.
TY