can anybody help me out, i have two hps lights a 400 and a 250, I would have just bought 1 600 but these two lights where an old friends that thought he wanted to grow and paid for the 2 lights but never even started,lol (NO IDEA) so i got them and hung onto them, now a year later I am putting them to use. I have an inline 4'' fan going into the wall resting on my top closet rack, i plan on air cooling both lights with this fan wall to wall using attic air. I am having doubts that this 170 cfm fan will do the job with both lights. QUESTION, do you guys think i will be ok cooling the 2 lights enough (or) do i need to put the 250 aside and use just the 400? Not to mention i really want to use both obviously all light will help, and moving to a 6'' fan isnt really an option b/c the fixture is already 4'' duct compatible thanks for any help you can give me.........