first, i think i commented on this filter in the gallery forum, but if not, i love variation #6.
and second, why would pedestrians be walking in a collection basin of a fountain?
and third, forget the second comment here

you talking about your porous pavers being used on like a sidewalk or something where there would be a flow of water going through the pavers as a natural, continuous and decorative effect? if so, then i think that would be pretty slick. you'd have to seal the top, though, the walking surface, wouldnt you? interesting idea. expensive, but interesting.
If wishes were horses... there'd be a whole lot of horse crap to clean up!
Craig