That’s a lot of questions I’m happy to answer. The full greenhouse set up is closed to the sun and uses all artificial full spectrum LEDs that put out around 350 PPFD at 18 inches distance from the light source. I use a ventilator to pull in outside air when the temperature heads above 85 or the humidity goes over 60%. I grow tropicals in the north.
I do supplement the CO2 supply with an Exhale bag of organic fungus. What I’m seeing is that the CO2 levels inside the tent jump from a low of 400 ppm around noon up to 2000 ppm around 5:50-6:00 PM. The fungus itself is light activated so I suspect it has a ramp up period.
That being said, even without the CO2 supplement, I still see the spike in the evening. I took measurements for a week without the Exhale bag and found that the spike maxes out around 1400 ppm. The air quality in my home fluctuates between 400-700 ppm so I’m sure the levels within the tent far exceed the levels outside of it even without a supplement.
Another theory I have is that I’m creating a CO2 trap inside the tent because the cooler air comes in from the bottom and hot air is drawn out from the top. The greenhouse is only about 6ft, but that might be enough given that CO2 is heavier than oxygen.
In any case, there are a ton of variables. So do you all know if a plants photosynthetic efficiency has a terminal point at which it says no more?