The PC fans diddn't seem to move enough air for my grow tent. I ended up getting 2 = $10 clip on fans from Menards. they worked fantastic and had 2 speeds. I adapted one fan to a 2 1/2" pvc pipe that went outside. The other was fix'd to blow accross the bottom of the light fixture ( HPS ) to keep the plant cool. All that and I still had 85 degree temps at times. Just a couple extra ideas for you.. There are some DIY carbon filters on the internet that can be built for spare change too.