what filter to use?

i'm gonna make a new homemade carbon filter that is filled with activated carbon and around that i will be using filter... but what type of filter should i use?... if i'm using activated carbon should i also use a carbon filter around the carbon? or just any filter will do?... thanks in advance!

also that's almost the same design: http://www.youtube.com/watch?v=JzkZgQkrT40

i'm only talking about the filter that is around the activated carbon...

More carbon the better
Use the carbon filter

The carbonj scrubber I have has a matted cloth pre filter which catches most of the dust. The activated carbon then removes the smell.