Just keep an eye on your water temperature after the power comes back on. My son had a disaster in the last couple weeks with his SW tank. The power was off for 8 to 10 hours and actually came back on during the night. When they went to work the next morning, everything seemed fine but when they came home, the thermostat had apparently hung up and the water was near 100 degrees. There were already a couple dead fish and the others were in bad shape except for a clown fish which are apparently very hardy. In the end, the clown fish is the only one he didn't lose.