if your goin vortex fan i just bought from here and their cheap too
Vortex 6 inch Inline Fan 449 CFM - Plantlighting Hydroponics
thats all the fan you will need

to set up go open 1 side of cool tube, exhaust hose on the other connecting to the fan then from the fan another exhaust hose to the carbon filter
you will want the fan to suck the air out of the grow tent and blow air out the filter