I have a 5 gallon bucket with the nipples on the side. Sunday morning it got down to about 27 here in Upstate South Carolina and the water had a thin layer of ice on top which wasn't too bad but I checked the nipples and they were frozen. So I went to Walmart and got an aquarium submersible water heater.
https://www.walmart.com/ip/Tetra-Submersible-Aquarium-Tank-Heater-10-30-Gallon/10291809
Last night the whole bucket had an orange glow from the little light on it letting you know it was on. It had a suction cup to hold it in place. I put it down at the bottom next to were the nipples are. Once the water reaches a certain temp, the heater turns off.
https://www.walmart.com/ip/Tetra-Submersible-Aquarium-Tank-Heater-10-30-Gallon/10291809
Last night the whole bucket had an orange glow from the little light on it letting you know it was on. It had a suction cup to hold it in place. I put it down at the bottom next to were the nipples are. Once the water reaches a certain temp, the heater turns off.