If you want to rely on critters to stir the sand , prepare to replenish often if their are any sandbed fauna predators present.
Needyreefer, Skylsdale, For me the starboard is about protecting my glass . Since I only use 1.25" of sand and most of my rocks sit on three points, much weight is transfered down. That amount of sand won't protect the bottom pane from pressure related issues. Plus, if anyhting sustantial should happen to fall, I feel I have done an effort to protect my tank and surronding space, not to mention my son. I have 120 lbs of rock and there are only six pieces that make up 110 of that. And I used HDPE from a plastic supplier in 1/2" thickness. Cost me 30 dollars. Not having sand, crushed coral, rubble or the like is considered BB. Starboard or any other form of HDPE is just a method employed by those using BB to give bite for their rocks to grab and protect the bottom. It also affords the added benefit of ease of cleaning and rapid coralline coverage. In my opinion, if one is not using 3 or more inches of substrate, HDPE on the glass is a good idea.