I have a 4k setup with 80 girls in an ebb & flow SOG style setup with c02 at 1400 ppms. My question is do I need to provide the room with fresh air other than opening the door a few times when I go in the room? My theory is that even with c02 in the room the air can be stale and will need to be replenished with fresh air....your input would be great, thanks.