Originally Posted by taylermckee
I have three bettas and they each have a heater. They are all in 1.5 gallon tanks so I bought heaters for 2 gallon tanks which was the smallest I could find. Two of the heaters I have are under-gravel heaters with no adjustments. They say they keep the water a couple degrees above room temp. The water in those tanks ranges from 76-80 most of the time. I have a different heater that is a submersible glass one, not adjustable either. It keeps the tank at 78 and only ranges a very small amount. I've read on here that fluxuating temps arent good so should I switch to the glass one for all the tanks? I like the design of the under-gravel though because it doesn't take up as much room in such a small tank.
I have no experience with the under gravel heaters, but the glass heater in my room mate's tank is terrific.
I'm waiting for a new tank to arrive in the mail (5 gallon) and with it, a new glass heater that's extremely reputable. My Betta boy Luna is currently living in a temporary 1 gallon tank and, although I can't say one way or the other with under gravel heaters, I can tell you to avoid this model like the plague:
It barely keeps my tank at 72-74 degrees, so I keep a space heater running most of the time to keep it at a comfy 76.