you probably get more co2 with the window being opened than breathing on your plants........co2 is only good when all other conditions are right and you have a constant measurement of how much co2 you are putting out.
keeko Reviewed by keeko on . CO2 from exhaling I hear a lot of people using dry ice, yeast and sugar, CO2 cartridges... but how effective would it be to just close windows more often? I heard CO2 levels are about twice the amount of CO2 outdoors. Also what about filling up bags of exhaled CO2? I know it sounds silly but don't humans and living being exhale a lot of CO2? Rating: 5