butters r you actually running something that displays your co2 ppm? I dont run co2 at night it shuts off when the room goes dark via
sentinel controller. Butters the reason you may not be saying your plants respirate co2 is possibly cuz your room isn't super sealed tight and the gasses escape.
A fully sealed room that is tightly sealed, espeically ones that are in basements, like my rooms are, while have a high level of co2 ppm during the dark cycle either because the plants respiratre the co2 and it gets trapped or because the basements naturally collect co2 cuz it falls to the basement.
As far as questions about the history of the earth, and co2 levels on earth over the millions of years its irrelevant. growing indoor cannabis doesn't mimic natural systems in any way. basically humans are creating a matrix like enviorment to maximize the yields of plants. so i dont bother trying to copy nature in any way.