My preference is to run a 4" or greater sandbed in my reef.
I prefer a 'deep sand bed' (DSB) for my reef tank, rather than a shallow one. When the flow moves it around, it doesn't end up with bare spots that way. From a maintenance perspective, a DSB helps with nitrate reduction and also makes it easier to reach items in a 30" deep aquarium. I chose to use larger grain (Tropic Eden Reef Flakes) specifically because I use Vortech pumps that can move water both with their ebb and their flow.