Exhale C02 Bags PPM Tested! - YouTube

this video shows that these bags actually increase co2 from 300 ppm outside a 4x4 grow box to over 1200 ppm inside. not a bad increase. they may not be as effective as dry ice and other methods but they are probably alot more accessible for people to get and for a fraction of the price of expensive CO2 system they'll offer improved results. IMHO if they raise the PPM of CO2 of the ambient air they can only help.