What CFM should my fan be to vent in air from outside to cool my 600watt HPS? I know I need two one to bring air in and one to exhaust air out so whats a good CFM on both of them. For 6 plants btw. TY
Depends what your air temp outside is really. I would go with oversize fan and a speedster controller. Once you get to the point of the outside air cannot cool it on full blast, time for plan B. I would imagine a 6", 440 cfm would do ya.
IMO the more air you move the better, use a 400+cfm fan and speed/temp controls on both the lights and grow area. The ideal temp zone of 75*-80* can be a pain to achieve but when you do your plants will reward you with outstanding growth and bud production.