300W heater with 30gal?

Actually, this is called short cycling and will give the heater a shorter life.

:iagree:

I think a rule of thumb is 5 watts per gallon. Your 300w will cycle on and off more than necessary. Just spend as few bucks more and get what you need for the tank. I don't think you can ever have enough filtration, but you can definitely go overboard with heat.
 
sounds tpo me you need a bigger tank to match the heater.
I agree.. short cycling may shorten the life of the heater.

but hey..you got it on sale right?
 
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