[mike31154]

Dunno about 'best' but here's what's happened in my tank so far.

Got a sand sifting starfish which spent a lot of time buried (good I guess) and not really moving all that much (not so good).

My female Maroon clownfish does a fantastic job of moving sand around below her BTA.

Gained a number of Cerith snails when I acquired a used 60 gal and they spent all day in the substrate then laid eggs on the glass during the night. They're quite small so I'm not certain how effective they are in a larger tank.

Also got a horseshoe crab from the used 60 gal and he was quite industrious. Large enough to make a difference too. Unfortunately, he didn't last. No idea what caused his demise. Not the most intelligent of critters, he'd go on these upside down swims and fall into my BTA, get stung, go limp and recover once the BTA released him as unpalatable.

At some point my population of Cerith snails declined as well. I think there might be one left. I see that most of my blue legged hermies are now sporting Cerith shells so who knows...

This brings me to my latest addition, a White Spotted Hermit Crab, cringe... This guy is a fair size and apparently not entirely reef safe. Probably not recommended for most tanks, but he can dig a mean hole and spends 90% of his time stirring around in the substrate. It's the other 10% that poses potential problems. I've been keeping a close eye on him since I do have a number of corals I don't want him messing around with and so far so good in that regard. I'm fairly sure he's the culprit in the disappearance of my sand sifting starfish since I observed him tearing away at it on more than one occasion. I figure one or two more molts and he's gonna have to go since he'll just be too big & destructive. Too bad since he's colourful & highly entertaining to watch. Leaps off tall live rock, faster than a speeding Cerith, smarter than a Horseshoe crab.... Then I'll just have to stir the sand myself.