So I finally have a chance to install my new air cooled hoods and want to do it the most efficient way that I can. When cooling your hoods do you draw air from the outside of the house to cool them and vent that air directly outside as well (in a completely closed loop)? I am going to be running Co2, so I am guessing the best way to run my vortex fans are to have them blow so that Co2 isn't sucked out of any little unsealed areas of the hoods/ venting? How many lights (8" vented blockbusters 1000w) do you think I should run per 8'' vortex fan? Appreciate the knowledge!