Hello all! I'm new to having fish. I got a beta fish as a gift. I bought a 3 gallon tank for it and I am having a hard time finding a good heater for it. I read on here that it is better to have an adjustable water heater because they work on a thermostat. Can anyone give me any suggestions. I did find the National Geographic submersible water heater with 10 watts of power, but it is not adjustable. Is that one any good? Thanks for any info.