Here what i have for ventillation on my grow cab, i also built the scrubber using the original posters are a template, but modified it abit because im putting a 6" inline fan in the bottom.


http://www.thefreeimagehosting.com/U...1340118024.jpg
http://www.thefreeimagehosting.com/U...0340117896.jpg
http://www.thefreeimagehosting.com/U...2340118152.jpg
http://www.thefreeimagehosting.com/U...3340118280.jpg
http://www.thefreeimagehosting.com/U...4340118408.jpg
http://www.thefreeimagehosting.com/U...5340118536.jpg

Mega i cant speak for the original poster, but if you have lower cfms then you have to build the carbon chamer thinner and longer so the air can pass through easier and in equal volumes. I made my filter almost twice as tall and about half and inch thinner as the original posters and the air flows out very easily. There is a pic of it in those links. I also put a bathroom cieling fan in the back and wired a plug cord on it. Fan cost me 39.99 canadian at home depot and moves about 90cfm