Haven't done three 600's but I do have two 1000's with a 6" venting system. I have fans everywhere. A/C, veg room and mom room plus 740 and 430cfm carbon scrubbers. A little noisy. Insulated duct reduces the noise a bit. I like to use more rather than less with fan size, then I use a 5 amp ceiling fan controller to adjust speed if I wish. 3 600's should be fine with 6" ducts but I'm not sure about the 4". Regardless, even the 4" will help some.
grey1223 Reviewed by grey1223 on . ventilation gurus help!!! quick question,right know i have an ideal setup of 2 x 600 watt in a 5 x 10room,however i need another lamp a.s.a.p. up until this point the room gets ventilation from a seperate room and exhausts into our main room"wich gets pretty hot. im afraid by adding another lamp its going to affect my veg room.i need some input on my idea, i have 30 ft of 4 inch schedule 6 abs pipe.my plan is to run all three lamps with my current 6 inch fan then reduce to a 4 inch reducer" to accomodate the piping" and Rating: 5