how many fans?

right now I have 4 retofitted 48" ATI bulbs in my canopy and the temp stay pretty spot on to the .1 degree. However yesterday it went up just a tiny bit about 1 degree. I am going to add 12 Cree LEDS in the middle of the four t-5s for some more power since I kind of ran out of room the way I built my canopy. In the back I have three 3" holes that I cut to allow heat to excape. Should I put fans on the holes to either pull in cool air or pull out the hot air? How many should pull in and how many should pull out?

 

I have not made a diy hood/light/fan set up yet, but this is what I've been told. Fans are good just about any time you can have them. It's best to run them pushing air into your hood so they are pushing dryer air because the humid air coming out of your hood will make the fans get dirty much quicker. I've been told that the method with one fan on each side with a vent in the top works well, and it's good to have a variable speed fan so you can control how loud it is.

 

You should have one blowing across the label end of the T5HO bulbs. It would not hurt to have one exhausting out on the other end of the hood.