Anyone here ever try a deep Sand bed in a fresh water tank?

Just on a whim after getting out of the Salt Water hobby, I tried a deep
sand bed of Playsand (About 4-6 inches) in my 80 gallon tank. I'm one of
those wacko's that likes to put local wildlife from my vacations into my
tank to see how they do. I've REALLY lucked out with some conical snails I
got while tubing down the San Marcos a year or so back. These snails have
turned out to be quite the sand bed cleaners and are breeding almost TOO
well. They keep the top inch or so of the sand churned quite well and have
left my plants alone. Also got some fresh water mussels breeding in the sand
bed and doing well. All in all, just with a simple overflow and a 30 gallon
sump half filled with lava rocks, I've had some pretty good success at
keeping a decently clean tank, though for now, my BIO load consists of but a
single 5 inch Pleco and 1 5 Inch Jeweled African (Any other fish added is
immediately harassed to death) I am in the process of raising 3 more African
Cichlids to "contender" size in a 30 gallon tank set up similarly.

Just wondered if anyone out there might have had similar results. Also,
was looking for suggestions on some safe critters I could add to the sand
bed to possible churn it a bit deeper than the snails.