I am right now trying to find out the best way to keep my cab cool and still be able to have co2 blow around? The problem i've been having is that my climate controller is putting my fan cycles too close together. not allowing my co2 to do its work. right now the cyle is 12 min fans off _ 4 min fans on. the fans are activated automatically by temp/humd rise. MY QUESTION is does anybody know if it is good to allow a constant intake fan into the cab which is air tight, thus expanding the walls cuz air has nowhere to go? cuz I noticed a huge change in fan cycles to 10 min. exhaust fan on- 50 min off. If i do this will it be more beneficial to my plants? Is the co2 just being forced to the top of the grow box or is it being bounced around inside?