The heat is from the bulb and the air around the bulb, A cool tube will allow you to get the light close or even a heat shield will work. You still need a blower to move the air through the hood or cool tube and out the other side.

For the record I can get 1000w hps as close as 12" and the plants love it. Yes I do have AC in that room but there is no cool tube. The lights come on in a few and I will show you how close it is.

Your friends had other problems; there are a few nutrient problems that have the exact same signs.
Zandor Reviewed by Zandor on . what ventilation system should i be looking for? O'k guys I have a few question concerning my grow room,I was wondering what I could use to dump the heat in the room and at the same time draw fresh air back into the grow room......here is my set up... The room is 9ft long 5ft wide and 8ft high my grow table that I have my plants on is about 5ftx4ft under a 1000w hps I am into my 3rd week of flowering and boy is the room getting hot! alot hotter then I anticipated!,I keep opening up the door to the grow room and at most times I leave Rating: 5