You chop the potato into small cubes, place in plastic bottle.
Then add enough hydrogen peroxide to cover the potato cubes.
The lid needs to be drilled so an air tube can be run through it,
Seal bottle and place tube with or without an airstone in the tank.

Hydrogen peroxide naturally breaks down into 2 components over time, water and oxygen, the addition of the enzymes from the potato speed this up 100x
The escaping oxygen gas will travel up the air tube into your tank, providing pure oxygen to the water.

Witchcraft!!!

Its pure Science ;P

I flunked science :wink:
cool though.

Takes prep time though, the potato/peroxide science, and you need to be home. One great feature of the battery powered air pumps (the ones I have anyhow) is that they sense power outage & switch on automatically. The magic of relays.

True enough, but if for some reason your air pump breaks or you run out of batteries its an option.

A low tech emergency back up.

If the power outage is that bad that im so out of options to that point... id be letting the fish go and cooking the potatoes.