For a sealed CO₂ room, you actually don’t want to exhaust too often, otherwise you’ll just waste your CO₂ and destabilize temps/RH.
Here’s the ideal setup:
Intake: Passive or filtered intake (only for emergencies or cooling help).
Exhaust: Keep it on a thermo-hygro controller let it kick in only if temps exceed your target (e.g. 30 °C / 86 °F).
AC + Dehu: Let the portable AC and dehumidifier (Quest70) handle the environment most of the time.
Circulation: Add strong oscillating fans at canopy level and under the canopy you want full air movement but no leaf flutter.
With that setup, your COâ‚‚ stays stable and your plants stay happy
If you want, I can draw you a quick diagram for the airflow layout.