Well, I DID say it was "extreme" and use only as "a last resort"....
But my Kirkland neighborhood was w/o power for 4.5 days that winter... and desperate times call for desperate measures!
-Battery/UPS back-ups will only last a few hours (or 1 day at most),
-temps in an un-heated house will drop to well below 50 degrees in winter (no amount of foam will keep the tank warm enough then),
-power inverters only work when your car has gas (gas stations need power to pump gas, and cars can't idle forever on a single tank.)
-and this thread started with the statement "I dont have a generator nor do I have the money to buy one, so dont say that".....
So de-icer pellets in a jug of water IS a decent solution for < $10, and it saved ALL the livestock in my tank that winter.
(FWIW: just putting Boiling water in jugs doesn't really last long enough, as the heat dissipates too quickly --since CaCl is a chemical reaction it delivers a more sustained heat.)
That being said, I personally have: foam panels, a 2000W inverter, long extension cords, battery-powered air-stones, and a battery back-up system running a small heater and power-heads--always ready, just in case.