Just ahead of time I wanna say, if it ain't broke don't fix it.. but just a little bit of info.. using co2 during the veg state causes the plants to stretch and stay skinny.. which may not be a problem if you only veg for like a week or something.. but it's just something to keep in mind.. congrats that you haven't had any problems though /quote]
I am almost possitive that co2 would have nothing to do with strectching. i injected co2 for entire life cycle and have NO stretching issues. in fact i have issues with my girls no growing upward and being extremly bushy.
CO2 is wonderful and if you can afford it, through out your yeast bottles and get a tank+reg and you will love it!