I would look in to some better more cannabis specific nuterients. And plants really only need CO2 in the later stages in flowerring and if you don't have ventilation then it will seriously hurt your yeild not to use it. Check this out, It tells you how to make a sugarwater co2 generator. Costs like maybe 5 bucks and will last 2 weeks.
CO2 Injection: The Yeast Method