i have 2 big tiger oscars, they are poop machines....you'd think a cat is in the tank
the hot setup to keep crap (literally) from settling on the bottom is undergravel jets, simply a submersible powerhead attatched to pvc to nozzles in variuos spots at the bottom of the tank, the gravel will hide the pvc, with creative pointing you can dirrect the flow of waste, most of mine goes to my pre-filter in my overflow and get's trapped in one spot.
here's a how-to for the ugj's
http://cichlid-forum.com/articles/ug_jets.php