Thought I'd start a thread so we all can share what tips and tricks you guys use to make life easier that may be common knowledge to you but not to others.
I always have a generator for power at my last place but only battery backups for the pumps here in case of power loss, and there isn't a battery powered heater that i know of so I've use this a few times and it came in clutch. 100% pure calcium chloride pellets, the same stuff you use to deice your driveway and is water activated, crush it up, put it in with water in a bottle, 50/50 ratio, close the cap tight, put the bottles in a double ziploc filled with water, clip it up right in tank, the heat transfers from the bottles to the water in the ziploc and then to the tank, double leak protection. I would not put the water bottle directly in the tank. Add more bottles if needed to raise temp, remove one to lower, last about 6 hours. Way more economical and efficient than hand warmers in a ziploc. You can get it on Amazon and there's a few brands, I didn't think i needed to do this until i lost power at my new place, so now i have a container on standby at all times.