I know global warming is bad but we're not exactly at 1200ppm of c02 in the atmosphere just yet. Outside air will give you 400ppm at most.figure out a way to get forced fresh air (outside air) into your grow room during lights on. was the only way I could get temps down in my room without spending a fortune on a/c equipment. added bonus - outside air is 1200 ppm co2.
right now im running 3-1000's on a closed loop with one of these http://www.htgsupply.com/Product-GrowBright-Mach-%208-Exhaust-Fan.asp, im not running co2 or dehumidifers or ac right now and my room stays perty much between 78-80 DegreesI know basements usually are cooler, but say you're running 4 600's, how would you go about keeping it in the 70's in there?