Review on Cobalt Aquatics 31020 5W Mini-Therm Aquarium Heater - White/Black, Energy-Saving Mini-Therm Heater, 5 Watt by Dwayne Pore

I would buy it again, it heats my 1.5 gallon thin wall plastic tank from 70F to 77F. It only has one suction cup, not two like the picture. It doesn't have a thermostat and is always on, so make sure you choose the right power for your aquarium size. The packaging states that this 5W unit is suitable for a 1.2 gallon tank. The package also says to buy a 10-watt 2.4-gallon unit, a 15-watt 3.6-gallon unit, and a 20-watt 4.8-gallon unit. Make sure you get all the air out of it before turning it on. The instructions say leave it in the water for 15 minutes before turning it on and turn it off for 15 minutes before removing it from the water. I think if air touches the heater core it will burn out. After waiting 15 minutes before plugging it in, I moved the power cord up very gently and it spat out a few bubbles. Most likely, air has entered the center of the radiator. I'll probably do this every time to make sure the unit is fully vented, even if the packaging doesn't say so. The only thing I don't like is that the white markings are printed on the front. Every time I look at the front of my tank the text on the heater is highlighted. See photos. I've only had it a few days, so I can't comment on durability, but overall it seems quality. The power cord is long and of good quality.