Mammals exhale and a portion of that is C02, this is true. However, theirs also a lot of non c02-age in what we exhale; Exhaling many times into a bag and trying to seal it repeatedly after each breath is way more effort & time in the long run for a much much much less efficient (& totally impure) result. You would probably be better off breathing in your grow space for an hour a day but this is just as much a waste of time.
frostymcfailure Reviewed by frostymcfailure 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