Any guidlines to air movement (cfm) in a hood?

[beviking]

Wondering (other than two fans) if anyone has an idea how much air flow would be needed to cool an enclosed hood housing 2-55W and 1-96W Power Compact Lights?
Since I'm DIYing it, I can choose from 40mm to 120mm fans, 15cfm to 64cfm.
One 64cfm fan or two ??cfm fans?

[OrionGirl]

Hmmmm. Well, I can say that we use 2 4 inch fans (no clue on CFM--they are standard 4 inch computer fans from Radio Shack) to cool the canopy on a 120 (4 foot by 2 foot, about 10 inches tall) that has 2 65W actinics and 2 250W metal hallides.

[beviking]

Thanks for the reply OG! Any chance of getting a make/model on the fans? your lights must get pretty hot!
The one I use now in my 18"X48" with 2NO and 2ODNO lights works well and I doubt it's moving any more than 10cfm (it was used out of a copier!).
I'm looking at a 120mm (~4.72 inches) that moves 64cfm, thinking it will be enough. Guess I could do a "dry run" when everything is set-up and if it gets too hot, add another. :idea2: Just have to plan accordingly...unless others have some input... :hang:

[chefkeith]

Unfortunatly, I think I might have to find a cooling solution for under my hood also. I have 6-55w and 2-96w cp lights in my hood. These lights are really cooking. I'm not complaining though because I keep a case of pudding snacks on top of there. Pudding taste so good heated up. I don't know if I can give this up yet.

Hmmmm. Warm pudding or keeping my tank water cool? Now that is the question. Right now, my fish are looking at me like I'm crazy, so I guess I'll put in a couple of fans and move the pudding to someplace else.