i have just built my grow room in an outdoor shed it is about 5 feet by 4 feet by 5 feet high i have 4 fluorescent light in it but i want to know what size and quantity of fans do i need to keep good circulation . would a couple of PC fans do running 24hr as they are very quiet or would i need something else a bit bigger i am only growing 2 plant in this area for now any help much appreciated thanks