MyCO2 Bloom & Grow are CO2 bags perfected. MyCO2 uses patented customer-activated technology, postponing the CO2 cultivation until you get it home and are ready to use it. One CO2 bag provides enough carbon dioxide for flowering or vegging plants in a 4 ft x 4 ft grow tent with cycled exhaust. Use Bloom during the flowering stage and Grow during the veg stage. We recommend safely placing multiple MyCO2 bags above the highest level of your plants to ensure they receive the CO2 as it is generated.