I think my main starting point would be: why are they sifting in the first place?
Lots of critters like those sandsifting starfish are after the good bugs that live in the sand. So they kill all your microfauna. Why would you want that?
Then there are critters that turn the sand around to burrow. Like my jawfish. I am okay with that.
Other interrupt the sand to hid like nassarius snails or fighting conchs.
So if I absolutely felt the need to have something dig in my sand I'd
* totally avoid all the sandsifting predators
* only get burrowers if your set up is really suited
* and probably go for hiders like the nassarius or fighting conchs instead
Honestly though why do you feel the need to have the sand stirred? If you do feel the need to have it stirred have you considered the idea that your own gentle scraping around might be more effective and targeted than that of some random critter?