Andy, you don't want fans aimed right at your lights.. A bulb's proper kelvin is reached at a certain temp. So if your bulbs are cooled, you will be messing with the spectrum a bit.
As Emily said, You want to blow at the surface.. Evapourate the top layer of water..
I have 575w of halides on my 50 gallon with a 4.5" fan. My temp is 79-81..
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