Use Azamax instead of neem oil. It is the concentrate of neem and easier to use. 3 treatments once a week will do. And it's cheap. They probbably don't have mite but just to be sure.

I know Zandor ran co2 and he said when the PPM's get to about 1500 no bugs could live and no bad effects to the plants for short periods like 4 hours or less. That's when you flush with fresh air and fill the room again.