Review on UL Listed NICREW Preset Aquarium Heater with Submersible Electronic Thermostat for Fish Tanks by Heidi Thompson

I need a heater for my 5 gallon reef tank. After reading reviews of temperature controlled heaters, it was reported that they often fail and overheat, heating everything in the tank to 90-100F! Risk of failure (at least overheating). I'd rather deal with a broken heater and cooler water than one that won't stop heating at all. I've had it in my tank for about 2 weeks now and it works amazingly well. The ambient temperature in the room is about 69F. After installing the heater, the temperature in my aquarium is constant at 22°C and the corals are happy. A little red light comes on when the device is warming up, so it's good to know it's still working. Definitely recommend if you want a heater with peace of mind.