Whether your tank is "overstocked" or simply has its maximum load capacity for balance is a matter of conditions and how much of a safety margin you want in case something changes. In your case, what with power outages occurring regularly, you would probably be better advised to either keep less animal stock or invest in a UPS that can handle your whole system, filters included, for several hours.
The answers given above sound reasonable to me, especially the four hour timespan before aerobic (good, beneficial) bacteria begin to die off and anaerobic bacteria begin producing toxic substances.
Your question reminded me of when I lived in Jensen Beach, FL, and some guy was doing about 80mph along Indian River Drive and took out a power pole around 2am (and himself, too, I think). I woke up that morning and found all the fish I had caught for my saltwater aquarium were showing signs of stress after being without air or circulation for over four hours. The tank was 6' long but only 45 gallons, so it had a lot of surface area per gallon, or else I suspect they would have already been belly-up. At the time, I couldn't afford to run out and buy battery powered air pumps and the power was out for several hours, so I ended up taking everything, fish, hermit crabs, etc., back to the reef/beach where I had caught most of them. (And before someone protests the re-introduction of captive animals into the environment, they were all native and everything that was in my only tank was locally caught/collected by me - nothing store-bought - so there was no danger of introducing any foreign species or pathogens into the natural environment.)
Oh, and my sister in law's remark was "Well, at least he didn't PAY for the fish."!!! I was more proud of and attached to those fish than if I had bought them!
Last edited by Darkblade48; 07-01-2016 at 03:25 PM.
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