I'd say most of the filters will be on their way out, if you've got a way of pumping through them to help keep some bacteria going, I'd get onto that.
As for oxygenation, I'd just keep refilling a bucket from the tank and then puring it back in.
I hope the power comes back for you soon, how's the temp doing as well?
You could put blankets / towels round the tank to help it if temp is an issue.