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[DiverDude]

Originally Posted by xtreme

I currently only run 2 250w on my 350g system. The only time they kick in is at night when the lights are of an the water cools a bit. Also, if you have more smaller heaters instead of 1 or 2 large ones you won't run the risk of a heater getting stuck on and frying your tank.

...or the opposite where one fails and your tank chills. Redundancy is king !