enough light? vpd? whatever....I'm lucky is all.
750ppm
@lights on , my c02 gen cycles only a few times #12 hours to maintain this and costs
12$ every 45 days in propane. If my gen broke I'd replace it in one day. Matter of fact I have a spare plumbed at the ready.
I dunno, but when I added c02 to my already cool space my buds finished with more vigor, terpenes and weight. My rh is always under 50%, temps under 80. The expense of ventilating while using c02 was crazy for me and I decided to seal up my rooms and never look back. I dont use outdoor air anymore and my costs were halved. Cooling, heating, dehumidifying control became very simple, set it and forget it for many years now. I dont adjust anything anymore. I've got 50 flowering plants in many stages of done perpetually harvested and never an issue.
My veg room shares the air with the flowering room, and while I agree additional c02 in veg might not be worth it, in my sealed rooms my vegging plants will suffer without c02 augmentation. I've done this with a full count of vegging girls in the past and learned c02 is necessary for vegging plants to thrive. Without it my leaves were weak, plants were spindly, tipsy, slow growing.
I'm sure with some more tech considerations my results using c02 could be even better.