We've got a 55 gallon that we are currently working on that will eventually be a reef tank. For what we are doing we need a minimum of atleast 4-6 watts per gallon. This is going to be about 8 watts but we know we have it covered and everything is going to thrive. We have in our house 2 55 gallon salt,1 60 gallon hex seahorse tank, 1 3 gallon micro reef, 1 37 gallon salt, 1 30 gallon fresh, 1 20 fresh, and 1 30 gallon terrarium with fish and newts.