Quote Originally Posted by criom
also i keep hearing that i need at least an 8" fan to move enough air to keep it cool, is there anyway around this?

they are really expensive and im wondering if a Suncourt 6" In-line Duct Fan - 300 cfm would be enough to cool it.
I'd match the fan diameter to the cooltube diameter.

You gotta remember that these tubes are normally content to run without any air motion at all- even a small fan, matched to the tube diameter, will be a big improvement.

I expect a cooltube to be about 3.75" dia. A 4" fan, of good quality, should do you just fine. By 'good quality' I mean cast aluminum body and ball bearings, not a cheap plastic bodied computer fan with sleeve bearings.

Any cooltube fan should be on the cool side, blowing air first over the tube socket and then warmed air dicted out of the grow airspace.

If you can't find an appropriate 4" fan in a duct, the 6" will do, using duct size reducers from Ye Olde Hardware Shoppe.

I don't think an 8" fan is necessary, unless you're pushing air through two 4" cooltubes.