To add; I’d imagine decomposition of compost further contributes to CO2. The fact that CO2 is pumped in to some commercial greenhouses suggests CO2 is a limiting factor in plant growth, but I wonder whether hydroponic systems - lacking soil and hence decomposition - require more.

Nice bit of work! Good that they supplied the supplemental videos, bit funny that they’re videos of videos.

Right but he’s not serious, he’s just doing a “in theory, what would it look like?”