i just saw that linked thread from above. if you could find a large chimney like that one you would be in business. i looked for a while but was only able to find smaller ones. the only thing is that there is no way the fan that that guy was using had enough power to cool that bulb. i had the same fan for my 400hps cooltube but it didn't have enough power so i had to hook the duct directly to the main exhaust fan, not the best solution but it got me through the grow.