Air flow

You would need a ridiculous amount of baking soda and vinegar to make a meaningful increase in CO2 levels in anything larger than a micro grow space. Honestly those bags aren't much better. If you wanna REALLY do CO2 injection then get a tank and regulator. Chances are you don't need it at all. You want some pretty high end light levels before it's useful.

Daytime plant wants co2, it eats it up fairly quickly as day progresses. Co2 runs out its out. If you have fresh air then your always replenishing that baseline co2. Nightime the plant needs no co2 as the plant itself creates co2 as a by product. What it needs at night is oxygen, not normally a problem, at night and early morning you will notice the co2 levels at its highest point. The light compensation point (Ic) is the light intensity on the light curve where the rate of photosynthesis exactly matches the rate of cellular respiration. So long as your not cutting of airflow entirely there will always be oxygen going around. Co2 is generally dense to so you can have the passive lower Intake you use for ventialtion just have it sucking the co2 from bottom 1"2" off the lowest point in any place where human lungs exist. Baking soda and vinegar works well too. 😋 faster shorter lived co2 dump, for early morning breakfast works best I found from my own personal experience. I stopped trying after a while as there is not much point until the rest of the cardinal parameters for growth are all 100% only then does co2 have benefit., even then you have to ramp up temps to 90 ish along with ppfds up to 1800 if your pushing it. To do so requires serious planning and sound environmental controls to deal with such a large transpirational footprint, don't even get me started on temperature controls. Took me personally 4 years to setup a tent capable of doing so. And a 14,000 btu portable ac to deal with extreme temps, high rewards for high risk, bit man it stresses me out switching to flower having to be dialed in every day. Knowledge first then apply. Just grow and forget co2, expensive gimmick. Setting up a good vpd with solid negative pressure within your tent can improve yields by as much as 20% making it about the same as co2 supplementation.

That won't work very well, a closed loop CO2 setup needs a precisely controlled environment and CO2 level. And for a CO2 setup to make sense you have to feed the plants +1.200 μmol light. CO2 bags don't really do anything and are not worth buying. If you mean that you don't have a fan blowing air into the tent, then that doesn't matter, passive intake through the bottom vents is fine.

I have run CO2 generators in an enclosed tent with my inline fan off - basements just too cold. Didn't have any issues on the 4 runs I've done it with