if you want to put Co2 into your grow area look at my tread
http://forum.grasscity.com/general-indoor-growing/110325-co2-has-totaly-turned-my-plants-around.html and look at how I made mine(second page, post #16). It has helped my plants a lot. You only need Co2 during flowering, at least from what I have been told.
I got these Co2 directions from Infiniteawesome