Originally Posted by Olympia
For five gallons there is a tetra fully submersible heater that you can get at walmart that has always done me a good job :)
I have a small Tetra submersible heater for my 2.5 gallon, and it's pretty good! I got it for about $15 and it keeps the water about 78F, and my boy seems happy.
I did notice that when I first put the heater in, I didn't have it fully submerged like the instructions said to, the water barely reached the top. Once I added an inch or two more water the temp rose from about 75 to 78F.