Right size fan/carbon filter?

One last thought:

that1guy1388 said:

Now if I go to Phresh's website and plug all my info in (length, width, height, number of lights) it says I need about 840 cfms.

Click to expand...

I think the Phresh Calculator is unclear on what "Number Of Light" means. One of my early grows was in 96 cubic feet and had 12 65W fluorescent light bulbs. According to their calculator, I required 1832cfm. LOL! That would have changed the air 19 times a minute... and if you were using 2 1000W lights in your 270cf area, they say you would require 390cfm changing the air every 90 seconds.