Fans are a great way to help boost productivity and can be placed very close to plants, to help strengthen the marijuana plant and move air around. A fan's ability to circulate air from one locations to another is measured in cubic feet per minute, so you should choose a fan based on the size of your grow room. Growers should find a fan with the capacity to circulate the room's air three times in one minute. For example, if you have a 4ft x 4ft x 6ft grow room, then it is 96 cubic feet and you should find a fan that is at least 288 cfm (3 x 96). If you have a warmer grow room, you might want to remove the air up to 5 times per minute, so you may want to invest in a grow fan that is at least 480 cfm. JUMP TO GROW FANS