I saw another customer use this in a birdbath, and thought I would give it a try. A little concerned about squirrels chewing on it eventually, but for the month of January in Hardiness Zone 6a it's kept the water in our larger birdbath ice free.On the day of these photos it was down to 12 °F overnight (15 when I ventured outside). We had a couple inches of snow, which is covering the smaller totally frozen birdbath. You can see the water in the bin next to it frozen solid.EDIT: Finally hit single and negative digits. I've been clearing ice with freash water each day (Starlings splash it all out with their vain bathing habits), but overnight the puck has to fend for itself. You can see the progression. Keeping in mind, this is not a bucket, but a wide stone bird bath, I think it's doing really well!Easy to live with, even without and armored cord (so far). Highly recommended for bucket or birdbath.