Using gravity to pressurise filtering ??

[MrCat]

I'm just thinking out loud here.
I've got a Z-filter which seems to do a pretty good job but I'm just wondering if it could be easily improved upon.
For some reason I was thinking about the filtering systems I know for other things and typically I've seen the unfiltered liquid put in at the bottom of the filter material and then the filtered liquid is collected from the top.
I can picture what happens when liquid goes down through a tube and the difference when it goes up a tube and to me forcing the liquid up a tube should improve the filtration system as the liquid should 'touch' more of the carbon (etc).
If the exit of my source container was say 5 feet above the bottom of a stainless steel pipe filled with carbon I should be able to generate enough water pressure to force the liquid up through the carbon. It will be (cheap &) easy enough to get a two foot length of 2" diameter stainless pipe, a couple of hose fittings, use the final Z-filter disks and make a pressure fed system.
Thoughts ??