setups

Hey peeps So ive been growing for some time using a home made RDWC system, my mate got me started having something simular on a larger scale (24 plants)... anyway simple gravity fed system The system did me solid for a fair few grows not bad for some PVC and fittings from the local hardware...

Ok so going to be doing a grow of 6 plants, in a tent that is 1mx1mx2m. however i am a bit confused on which size of extractor, inline, and carbon filter i should be using. there are 4" setups, and 5" setups and obviously much bigger ones. which one should i go for to ensure smell is...