My 10 watt Aqueon heater is no longer keeping my betta's water at a good range, and it's not adjustable. So I'd like to invest in a new one, but I can't find any below 25 watts that are adjustable. I'm wary of getting another automatic heater because of my experience with this one.
This one has excellent reviews and is adjustable, but would it be unsafe?
Could I set it low and slowly increase it until it gets to the right temperature?
Would it simply not fit in the tank?