So we had an early cold front on friday that has had daytime temps in the 50's & 60's and night time temps in the low 40's. The water was 79F when the cold front rolled in and I was able to easily maintain the temp at 74F over the past 4 days without burning too much wood. It is supposed to warm up the rest of the week into the 80's, this is our typical winter cold fronts where it is cold for 3-4 days and then warms up until the next front comes in. So I'm pretty optimistic that I will be able to keep the water temp in the 70's throughout winter and make this a tropical pond.
I snapped some pics after it was dark so they're not the best quality...
My heater in operation
These are the corrugated plastic pond insulators I made. The wind kept making them stack on top of each other so I siliconed some pieces of nylon drywall corner bead on them to stop that. I think when I get the pond better insulated I'll be able to keep the pond warm even when we get stronger cold fronts.
And my channel cat was swimming around waiting for his nighttime feeding so I snapped a couple of pics. He's a bit over 2' long now.