Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
You might end up cleaning the sand by simply waving your hand or a small tool over it, creating just enough water movement to push the debris over onto the planting substrate.
Do not dig into the substrate like you do with a gravel tank. Use a much smaller siphon and just barely touch the surface of the substrate, or move the plants with your hand to allow the debris to be sucked into the intake.
Mostly, though, the debris is left to rot and become fertilizer.