Yes, I think you are helping. I just did some research on the dual hose and it looks like it recirculates the rooms air while the hoses keep the unit itself cool with outside air. That solves keeping co2 in the room while the lights are on. The only thing is I'll need to cool two of these rooms. I really didn't want to buy two of them.
I think I read that plants don't use co2 during the dark hours. If so, wouldn't it make sense to vent the rooms at that time? I was hoping to keep the rooms airtight while the lights were on and recirulate the air/co2 mix, then when the lights went out a timer would turn a fan on and "flush" the room out for a few hours.