ive always seen them and done them where it blows into the socket base side of the reflector... if all you want to do is cool em off, use a 150. valuline, can fan, fan tech, dayton (squirrel cage), or sun court. personally, i use the can fan Fan Max. they are some bad ass fans...just depends on how much $$$ you are willing to spend. BGHydro.com has the best deals ive ever found. way fuckin cheaper than msrp. idk what size you need, but id go at least a 6" to really keep em cool, and it will allow you to place the tubes much closer to the plants without burning your babies.