I dunno if this is old, but I dont usaully post here. I use a 600w HPS in a space 2widex5longx9tall, its hooked to a 6" valuline, it connects thru the top of the hood with a homemade adapter (think oldder sun systems hood with air kit), I removed the glass as well cause I figured my space wold be small enuf to use one fan for venting, then ran that to the ceiling and vented it to the mini attic. My plants can grow to within 10" of the BULB with no stress. All I got running is two small 9" fans to strenthen stems with that blower and I can leave the door closed temps @ 78 here in summer in cali.