So I got my son a new betta & 'upgraded' from a 1 gallon to a 2.5 gallon with a heater. I've tried 2 different heaters, the submersible ones that u don't have to adjust. The one I'm using now is supposed to work for up to a 10 gallon tank, but its not very consistent, even tho I'm keeping the glass top on the tank to preserve the temperature. I've spent more money on this setup than I care to, but it thrills my 3 yr old son so I guess I'm willing to make one more investment. When I was a kid we always had the heaters that u could adjust manually. I can't seem to find a manually adjustable heater for our size tank. I'm sure someone here can tell me where to get one that won't cost me another body limb?