Yes u can and u may not even have to turn ventilation off. I have full in and out system and i run lines over my canopy and run co2 all day with all fans on etc. Heres what i wrote on another thread about co2
My info on CO2:
Here are some pretty much facts:
Adding the correct amount of CO2 at the correct times (which is most of the growing phase) will consistently add 20-35% increase in yield.
Bigfattomatofarmer was right on the button, general CO2 levels range from 200-500 ppm.
In terms of what is the correct amount of CO2, this is how it works. Unfortunately I dont have a diagram to assist but its pretty straight forward, the maximum saturation level is 1800ppm, anything over this is a complete waste. The absorption rate plateaus at around 1500 ppm, in the sense that the difference in absorption between 800-1300 is huge, but the absorption increase between 1500-1800 is VERY MINIMAL. Therefore in my experience I like to keep my open rooms at 1200ppm and my closed rooms at 1500 ppm.
In terms of when the correct time is , i love to blast co2 strong all veg, no extra co2 the first week of flower and then strong co2 during the rest of flower, and finally NO CO2 during flushing weeks at the end. Reasons being a) some people say co2 in early flower will cause a bit of stretching (althought others claim you can run co2 all the way through, the difference probably isnt huge). But no extra co2 the last two weeks is good because by this time most or almost all of the size has finished grow and you really need the plant to focus on maturing so excess co2 is wasted.
To install a co2 generator or not? Well you have two options A) a propane burning generator and controller and B) Bottle co2 (tanks) plus regulator and controller. Either of these ur looking to spend prob close to a G (1k). FOR SMALL GARDENS U CAN USE CO2 PUCKS. My advice: ALWAYS ADD CO2 if you have a 1 lighter in the closet use co2 pucks if you have anything bigger than that pick one of the systems and get going! I use bottles they are easy and IF YOU HAVE CORRECT AIRFLOW CO2 CAN BE RELEASED ANYWHERE, if not set up lines above the canopy so it can fall directly on the plants.
smoker out
