How long can a tank go without power for? FYI: power outage in Coq, Burnaby and NW

[o.c.d.]

If you have a cordless drill you can mod a kitchen spatula to fit the chuck and spin or run out and buy a real paint mixer that fits your drill. That assuming you have one. Or siphion tank water in bucket and pour back in like a surge devise. Same as the pitcher method just upscale. I bought a battery back up that switches on when the power goes out so if I'm not hm it will still turn on, it will keep a single powerhead on for long long time esp the low watt units. Then for extra back up I have a generator.