A bird bath heater would be great if you were using say a 5 gallon bucket. Thats what I'd use. The big failure on aquarium heaters is they are typically covered glass and if the water drops too far down, the glass heats up. Water gets splashed, and the glass breaks, exposing the heating wires to the water which is now charged from the electricity.
I got a good zap from an aquarium heater years back and I ALWAYS unplug mine now since then. They do make glass-less heaters which would help. The standard recommdation for an aquarium heater is 3-5 watts/gallon. So even a 25 watt heater is going to be plenty for a 5 gallon bucket. You'd have to remember to check it when you went out to feed in the winter, but I think it could safely be used.
I still like the bird bath heater with a 5 gallon bucket. Its safer, and lower wattage. Id drop that inside the bucket and be done with it. I bet the warm water inside the bucket would keep the water inside the nipple from freezing up. That warm water may even keep the nipple warm enough to keep from freezing too. Hard to say but its worth a try.
Id get a lid for the bucket, make a notch for the wire to come out and plug it in. The cover will help retain heat too so its not being lost out the top from wind blowing over the warm water (just like we blow on the surface of hot liquids to cool them to eat).
Keep us posted Monty.
why didn't I think of that? Don't feel bad I missed that too
