Sand sifting starfish compatibility?

It will not be a live sand bed for long if you add a sand sifting star. They feed on EVERYTHING that lives in the sand bed. A 30 gallon is not large enough to have enough area for sand to support one anyway. The star would quickly eat any thing living in the sand and starve to death. Not to mention you would never see it as they burrow under the sand and stay there most of the time. If you are looking for things to stir the sandbed use some narius, astrea or conch snails.