Quote Originally Posted by tripleblack
Cheers guys. I plan to run a 400w sodium light. Is it wise then to get a larger fan and a reducer? ie is say a 10" fan running at 25% going to be quieter than a 4" at 100%?
Yes this is a good practice. However...dont ever get more then a 6". A 500cfm 6" inline fan will cool 2 lights and a larger room no problem. A 10" fan will move around 750cfm or more and be very loud. Run a 4" inline with a speed controller, thats all you will need. If you ever plan on upgrading to a larger room or something, then get a 6" and turn it down a lot.