The Titan Controls Atlas 3: Day/Night CO2 Monitor/Controller is one of the best ways to control grow room CO2 . Maintaining the ideal grow room environment is absolutely essential to cultivating huge, potent plants, and maintaining proper carbon dioxide levels plays a huge role in this. If your plants don't have enough CO2, your harvest will be dismal. But, if there is too much CO2 in the grow room, it creates dangerous conditions. That's where this controller comes in.