Update,the filtr/screening that comes in the ends of these chamber should be removed.After reading Dakar's post,I decided i'd take a look and see if i was getting any crud/parrticulates in the chamber.Sure enough,the filter floss material that is on each end of the caps was already brown.It's a PITA to remove,its really glued into the cap well.There's a grey plastic circular ring that needs to be removed before you can access the filter material.I just used some needle-nose cutters and cut it out.The filter material is not at all easy to remove.After struggling for 10 mins with various knives/tools,I finally just took a razor blade(a scalpel would be idea)and cut the filter at the plastic where it was glued down.
RESULTS-the flow is much better now and it is no longer back flooding out the intake.I'd recommend useing the filter bag this way as without it,the carbon might find its way out of the chamber.
Dave,the media bag i used is a 10"x3" draw string type media bag.It can probably hold about 2 cups of carbon,I just used about a cup.
CAUTION-for those of you who have never used carbon filtration before,you should start out with very small amounts.Say 1tblsp per 20gal,it is very effective at removing those yellowing agents in the water and when used aggresively/first time,the dramatic increase in water clarity might bleach your corals.