What is the normal CO2 outside?
Answer: The normal CO2 level outside is between 300-400 PPM. Some Co2 Monitors tell you to test the CO2 meter by taking it outside & test the outside CO2 level.
Hydroponics University
Hydro-U is a service of Simply Hydroponics and Organics On-line as part of our consumer education program. We welcome your feedback. Your input is what makes this site work. Please contact us with any questions or ideas.