No, it doesn't work, at all. Ive released an ENTIRE 20lb co2 tank into a very small room to test this theory. Does not kill spider mites OR root gnats. Its also dangerous unless done in a very controlled setting.
Everything i post is information ive found on the internet. Any and all info/photos are from websites ive researched.
I put my entire microgrow in a very large plastic bag and inflated the bag like a balloon with pure CO2. Was at least 50% concentration for 8 hours.
Repeated with increasing concentrations- no dice.