Fish can go several days without food and no issues.
What do the tanks have on them for filtration? If its canisters one of the issues is the crud and build up inside of a canister can become noxious. Especially if its been a while since they have been cleaned. When the power comes back on they dump all that back into a tank and can do some serious damage. Is there some containers you could get. 5 gallon buckets or other stuff and go get water from somewhere else? Definitly make sure you get some occasionsal water movement at the surface. You can also dose with Safe or Prime to help keep toxic effects of Ammonia and Nitrite down. remove any of the loaded up mechanical filtration material and it may be best to actually take any of your Bio media and put it directly in the tank.
What do the tanks have on them for filtration? If its canisters one of the issues is the crud and build up inside of a canister can become noxious. Especially if its been a while since they have been cleaned. When the power comes back on they dump all that back into a tank and can do some serious damage. Is there some containers you could get. 5 gallon buckets or other stuff and go get water from somewhere else? Definitly make sure you get some occasionsal water movement at the surface. You can also dose with Safe or Prime to help keep toxic effects of Ammonia and Nitrite down. remove any of the loaded up mechanical filtration material and it may be best to actually take any of your Bio media and put it directly in the tank.