A few hours should not be a problem ... but one caution: if there is no water movement in a sealed canister for longer period, stuff breaks down anaerobically to toxic H2S & flushing that into the tank when power comes back on that might kill fish.
In case the outage is longer than expected, you might want to open the canister during the outage to prevent that. <Keep water in filter to prevent your good bugs from dying>.
Also, battery powered airpump is a good idea.
80 gal FW with 30 gal DIY wet/dry/sump.
9 fancy golds, 1 hillstream loaches, 1 rubber-lip pleco (C. thomasi), 3 SAEs, small school of white cloud minnows, planted.