they move air, when it necessary to move more air you could get more fans or bigger ones, you'll want to exchange the air in the tent using one of the vents if you keep the zipper closed full time, sucking out will do it, but then odors may bug you too, then its time for a stink sock, a larger fan to draw=200bucks ish...then pests come, then you realize cheap ferts are difficult to work with and will want a system thats friendlier. then comes flower, more heat, more humidity, you may want to use a dehumidifier to control it or risk moldy buds. I lucked out and started with the whole programs, every bit and more than I needed, settled on pro mix organicare fertilizer and water for my win.