How long can inverts live without power?

[sinner's girl]

I was gone this weekend, I wanted to be home, but Sinner had surgery on Thrusday and found out friday he had to go back on Monday. We didn't want to pay for the gas.
Anyway. They were out of power for 7 hours across town. My tank is fine. The filter didn't come back on because the water level was a little low, but everyone was alive and moving about. I know we were without power, but by the time I found out about it, power was back on, so I could see the point in driving home.
Anyway, this re-enforced that I'm getting something to run the ph if the power goes out. What's the best (cheapest) way to go?

 

[socal57che]

I install battery backups for computer systems all the time. I don't know how long they will support heaters, pumps, etc. but you could use one for each item. They simply switch to battery power when the power goes out. Any local computer shop should have them or you can do a search online.