Two of my three aquariums are losing heat, and I'm trying to figure out why. At first, I didn't think they were actually losing heat, and I just thought my digital thermometers needed new batteries. I changed them, but that wasn't it. My next thought is maybe the heaters were broken during a power outage I had several weeks ago. Could a power outage cause heaters to lose proper calibration, or to even stop working? I've noticed the heaters kicking on, though, so I don't think they're completely not working at all, yet something is definitely going on. Just wondering if anyone might have any thoughts.