canesisters
Herd Master
I use a bird bath deicer in a plastic feed pan (roughly 2 gals) for my chickens. It's probably 4 years going and has never gotten hot. Look for 'deicer' not 'heater'. You probably want something made to JUST melt ice and not to heat the water.
Probably not the same brand, but looks like this
This little guy - of course - won't do a 70 gal tank.... LOL - unless you string half a dozen together
Probably not the same brand, but looks like this
This little guy - of course - won't do a 70 gal tank.... LOL - unless you string half a dozen together