Exaust question..

Is a 250CFM 6" Inline fan (HTGsupply) enough to suck air through a CAN 33 6" Carbon filter and properly exaust a room that is 39"x39"x72 ???


Would a seperate fan of this exact make do the job to cool a 250W HPS in an enclosed case with sealed glass?

http://www.htgsupply.com/viewproduct.asp?productID=46447
I assume this is the fan you are talking about? That fan is designed to boost the airflow in a duct, or help with intake air. It is NOT designed to pull air through a filter. Directly from HTG's website:

Effective treatment requires the exchange of air in the growing area in a period of 5 minutes. Compute your requirements by multiplying the width times the length times the height of your growing area to obtain the total cubic feet. Divide this number by 5 to determine the proper filter size needed.
For example, if your growing area is 8 feet long by 8 feet wide by 8 feet tall, it contains a total of 512 cubic feet. To treat this area in five minutes, you would need to use a fan with a CFM (cubic feet per minute) rating of approximately 102.

I use this fan/filter combo for my closet. Works great for me. My closet is about 5 feet wide, 2 feet deep, about 6 feet tall. :http://www.htgsupply.com/viewproduct.asp?productID=52531

use these fans http://www.hvacquick.com/spfnconfig.php?fm=td

Well this fan easily meets the requirements needed to exchange the air. I am unable to find where it says the fans are not rated for use with a carbon filter. Its not that i dont believe you, i just wonder if it will work anyway. Not to mention the guy below you suggested another, less powerful inline fan instead......

After attached to a carbon filter that fan will be 30 cfm maybe. Like pokesalot said, the 4' fan/filter combo will be more like 150 cfm after attached to the filter. More efficent and better for venting the room.