The trick is properly sized substrate, (cap over dirt in my case) and Malaysian trumpet snails to keep it turned over.
Here's how you get that correct size - Andy taught me this - thanks Andy.
You make 2 strainer boxes, one with 1/4" screen, and the other with window screen.
You first strain your rocks (from a local beach in my case, and full of clam shell fragments to boot) through the larger 1/4" screen, that get's rid of the
stuff that's too big. You then screen it through the smaller screen, that (obviously) screens out the stuff that's too fine.
What you're left with is a perfect substrate of varying particle size, but coarse enough to allow detritus to settle into it, yet not too course.
Works great as a cap to dirted tank.
This tank is heavily fed, 3 years old, and as you can see no visible detritus on the surface, just underneath however...
Larger rocks were thrown in afterword for effect.