One common trick is to spread new sand over old to get that really clean look before photoshoots/contests.
I came to think of it when I recieved the latest TAG:
On the front you can se a close up of the ADA Grand Prize 2007 "Ashy Range" by Dave Chow (
Creative Aquascape Union). If you look really close you can se algae infested marbles next to sparkling clean sand. More importantly you can se small specks of new sand ontop of the drift wood...
Very effective way of getting that over the top clean look.