I'm going to be building an outdoor pond of 15 feet long by 10 feet wide and 12 feet deep starting around April. As I live in southern kentucky, our winters get down to the single digits, and I'm trying to figure out a way to keep the water at around 60 to 65 degrees Fahrenheit. It's going to be stocked with local fish so thats about as high as i want the water to be. Does anyone know a decent way to keep the water around that temperature all year around without running up the power bill. Creative solutions are welcome lol