Yeah I agree with mafia, like i said I lived in a place where it was regularly 95+ in the summer in a 5'X4'X20" cabinet, a 400w lumatek dual ballast with agrosun mh and hps, ran through a cool tube. Like he said, you can get a cheap collar that fits over the blower, don't worry about modding it to pull air through, just push air through, they run at somewhere around 400cfm. Duct the blower straight to the cooltube, attach an inline fan directly to the other side of the cool tube. To run a carbon filter it will be necessary to use both as it will cause a little back pressure and that little bit of pressure without the correct flow rate will cause heat build up in the tube which will slowly increase the average heat of the cabinet/closet/whereever. The inline fan and the blower with collar and ducting you can get at a home depot or lowes or wherever for around $90, and they are reliable so you dont have to worry much about them burning out. If you're on a budget with your setup, there's no need to order something specifically for growing (as it will be more expensive), it's easy to just repurpose something cheaper, and more fun i think. For instance, I am building a fogger/dwc 400mh/600hps setup. I could buy the nutramist fogger and a prebuilt dwc system for like 800 or i could design it to my specs, and build those two components for about 250. Basic schematics of my old cooling sytem:
-->in--->blower---->cooltube---->6"inline fan----->carbon filter-----> out-->
thermostat set to 72F, 74F ambient room, 78F cab, 80-95F+ outside, never burned out.