My heater, as another poster said, was for tanks UP TO three gallons, and place din a 2.5. It brought the tank to 90 instead of the advertised 74. I have a tetra heater from walmart, and the tetra heater is a 10 watt and keeps mt 2.5 tank at about 78 in the same room, in the same spot. It keeps the 5 gallon at the same temp, though it takes it longer to reach it.
The heater I got was not recalled. I expected better, and instead wound up with a 90 degree tank. I don't think that's causing needless alarm to members-- I think it's ranting an d I've got a right to because a product did nearly cook my fish, and it was from a trusted name.