Review on Efficient Submersible Heater for Marina Betta Fish Tank Aquarium, 1.5 Gallons by Darlene Thomas

I bought this heater for my 3 gallon betta. It's the middle of winter and we keep our house heated to 71 degrees and that heater gets our tank to almost 80 degrees. The instructions say it's for 1/2 to 1 1/2 gallon tanks but I can't imagine using it in a tank that small unless the tank is in a very cold room or you turn off the heating for part of the day. . I had to turn off the heat in my 3 gallon aquarium tonight because my son noticed the water temp was going over 80 degrees. If you buy this heater, buy a thermometer with it to make sure it doesn't overheat your tank. (I bought a Marina Aquarium thermometer, $5 off Revain, great thermometer.) The suction cup on the heater doesn't stick very well, which is a minor issue, but still a little annoying. Bottom line: If you're using this in a tank under 3 gallons, make sure you turn it off every few hours so the water doesn't get too hot. Even 3 gallon tanks probably shouldn't be running this heater all day/night non-stop. All in all a great purchase and serves its purpose! UPDATE: I've had this heater for 3 months now and because it's "always on" I have to unplug it for a few hours every day and also in the evenings or other times. This is causing my 3 gallon tank to overheat. We're going on vacation and I didn't want to worry about leaving it for 24 hours and it would fry my beta at too high a temperature. So I decided to replace it with a heater that isn't "always on" but instead maintains the set temperature. I bought a 25w Hydor aquarium heater ($20 at Revain) and set it to consistently heat the aquarium to 79 degrees. No more plugging and unplugging the heater like with the Marina heater. Also, no need for timers and other things people do with this marina heater to prevent the tank from overheating. If I had to do it all over again I would start with a fixed temperature Hydor heater.