I just put a bucket/utility/birdbath de-icer in my 3.5 gallon plastic bucket nipple waterer and it works great. Just checked it after a 20 degree night (that's farenhiet) and it worked great. This was my first real test after one night of it freezing. I was concerned the nipples that were exposed may freeze but they didn't. I would recommend this to anyone that can get electricity into their coop. I just run an extension chord from my pond outlet about 20 yards away. It works great. Just make sure you get one safe for a plastic bucket if you use one.