How many watt heater would be good for a 180gallon and what is a good brand...I have 2 small heaters in my sump and it stays between 68 and 72 degrees...I used to have 2 in sump mag 1800 pumps...and hooked up an external pump...so my temp has dropped off alot...this tank has FOWLR. Thanks Is 68 to 70 too low? What is an ideal temp....76 to 80?