I lost power last year when we had the ice storm in San Antonio, 28' outside and it got down in the 40's inside. By the time the power came back on my larger tanks were in the mid 60's, but my seahorse fry tank was down in the low 50's (the fry were just laying on the bottom of the tank). After a gradual rewarming, everybody was fine. I know several other people that had the same problem and did not loose any of their critters. Saltwater fish and inverts are incredibly tough. Best of luck. I am sure they will be just fine.