Do you mean to use a air cooled reflector to exhaust lamp heat and air exchange?you could,but your open reflector will attract dust and airborne particals as well,some of which will be trapped in the foilage and coat the bulb,that will hinder some of the light output and the plants ability to absorb fresh air,I would use seperate fans,one for the hood with the lens on(the lens protects the bulb from dust and contains the heat)the other for air exchange(a 148cfm for each will work fine)