Tetra Submersible Heaters

We used these in 3 different 5 gallon aquariums. All the heaters were bought at the same time and all 3 installed into an aquarium within a week of each other. The first problem we had was that, even though it was the recommended size for the aquarium, one heater kept the aquarium too warm. Because we couldn't adjust the heater, we ended up taking it back and getting a different one. The other two seemed to keep their respective aquariums at just the right temp.....for about a month. Then one heater just quit working, and the other overheated the tank during the night. We woke up to find the fish lethargic and gasping for air - the temperature in the tank was almost 90! Fortunately, after unplugging the heater and letting the tank slowly come back down to temp, we didn't lose any fish. Needless to say, we replaced both of the heaters with another brand.

Pros: Easy to use

Cons: Unreliable

I bought this for my 55 g but they dont make a heater for that size. Or maybe walmart just didnt sell it. So i bought two for each end. Worked well

Pros: works well

Cons: only certain sizes