Co2 levels rising in the lung room.

2 weeks ago I chopped golden goat and got her hanging in the 2×4 dry tent. Another week and a half go by and I chopped frequency shift. At that point I shut down my co2 controller since the flower tent was now empty. I transplanted my ethos strains and threw them in the flower tent to veg for 2 weeks before flip, at this time co2 controller is still off but noticed the tent would be averaging 500-600 ppm day/nights. Yesterday I killed the lights in my auto flower tent, 18 hrs ago. Now my pulse pro is averaging 700-900 ppm day/nights. Pretty dang impressive that you can generate your own co2 by running a perpetual grow if you always have a couple plants drying/curing in your lung room.