I'm by San Antonio so our winter temps are pretty much the same. I have a 25000 gallon in ground pool that I converted to a pond and the lowest water temp this winter has been 49F but most of the time the temp has been in the mid 50's. So you would probably see similar temps during the winter or maybe a little cooler. I ran two 1000 watt heaters for a week and they made no impact on the water temp, also tried covering the pool with plastic and that didn't do anything either. It's really hard to affect the temp of such a large volume of water so I think you'll have a hard time keeping trops. I have koi, channel cats, and a couple of Chinese HiFin Banded sharks, and I added one Texas cichlid this winter and he has handled the temps ok. I'm planning on adding some hybrid striped bass also.