Checked that guide out. Pretty good compilation and even though the CO2 section is pretty comprehensive, it still doesn't explain the cycling in and out of fresh air while the CO2 is pushed. Or, do I set my controller to exhaust only when temps get too high? Or do I not need to exhaust at all due to the plants getting the CO2 they need? Trying to get this down while stoned isn't probably the best time so, but if anyone can comment.