The Puffer Forum

I bought this thermometer from a local pet store for my new betta aquarium because it seemed like it would be easier to read than the other weighted thermometers they had that sit at the bottom of your tank. That is definitely true, it's easy to read given that it sits right up against the glass. It did actually scratch my tank because I moved it by just sliding the magnet on the outside of the tank rather than placing the thermometer where I want it and then placing the magnet accordingly. That was my own fault, nothing that was a flaw of the thermometer. The biggest issue I have with it is that it is off by four degrees. Once I set up my tank and waited 24 hours for my heater and filter to circulate the warm water thoroughly. However, the temperature wouldn't go above 72 degrees so I assumed that my heater (which has an automatic thermostat) was malfunctioning so I exchanged it but still had the same issue; the temperature wouldn't go above 72 degrees which would be too cold for my betta. So I compared the thermometer to a high end temperature controller with a temperature probe in a glass of water and it consistently showed that the little aquarium thermometer read four degrees lower than the actual water temperature. I won't be exchanging the thermometer because a new one may also be off. At least with the one I have, I know when it says 72 degrees it's actually 76 degrees. It's a nice design, just wish it was more accurate.