Unidentified aquarium heater
So one of my friends moved a while ago, and left me his 55 gallon. I was digging around in the equipment box and found an aquarium heater. I wasn't able to find any information regarding quality/wattage/etc. It's glass and on the black lid it says "Whisper". Other than that there is no text whatsoever, except for the characters "05G23" printed on the top. Does anyone recognize this?
So is this too powerful to use in a 5 gallon nano?
How I feel about non-planted aquariums.