CFM rating for cooling fans?

[papagimp]

Been looking at multiple options (aside from a chiller) to cool my 75g down some. 2 x 250 PFO MH's 10" above water surface and still getting upwards of 83 degrees. The temp doesn't really bug me, but I'd like more "margin for error". Currently have a 20"ish tall canopy, with two radioshack fans built in, not sure size or specs on those, they help some but feel like i need a couple more. The fans I've seen have been around 35 or so CFM, than I've seen others around 100-105 CFM, so, what's doable and what'll help? Is 35 CFM sufficient to help cool a tank? (plan on these pointing at the waters surface in the display if that helps)

 

[MSU Fan]

Is noise a concern? there are quite a few fans that push a lot of air. That being said, I recommend Silenx fans. If you put 2 120mm (4.72" each) on variable AC to DC adapters, you will get a ton of air movement. Make sure each points in, and each will provide 72cfm to 90cfm (1" or 1.5" thick respectively) at less than 20db (that's a whisper in a quiet room, btw ). Unfortunately, you have to order them online which makes less convenient to get and you have to pay shipping, but their worth it.

 

[papagimp]

noise is definatly not a concern. The rooms noisy anyways, I doubt the noisiest fan on the market would phase that.

 

[latazyo]

I just bought two thermaltake fans from newegg.com for $23 shipped total for two...they are very quiet (although not less than 20 as MSU fan's fans are)