I am technically recirculating the air when the exhaust is in use. I suppose my hope would be to be able to get the humidity into the drain through the dehumidifier that way I won't be wasting CO2 with an exhaust fan. I should likely install a larger exhaust fan as well even if it's just for the high RH days... Or vent it to the outside as suggested.
Ahh.. that’s where numbers and math are gonna come in. Figuring out whether it’s cheaper to dehu or if it’s cheaper to replace lost CO2. I imagine this is going to heavily depend on your cost of power vs co2. That’s a bit more technical. Figuring out your air exchange rates, level of CO2 replenishment, and kWh for dehus
My gut tells me it’s easier, cheaper, and more efficient to replace co2 but I don’t know the costs so I’m not willing to die on that hill lol.