[Sk8r]

Oh---somebody asked about the diamond goby. Hundred gallon tank, maybe two hundred, and I'd also recommend eggcrate under the rockwork: they're keen excavators, and throw sand...they do TOO good a job for a small tank, and many who don't learn to eat prepared food will starve to death.
They are so efficient they stripmine the sandbed of edibles, weaken the sandbed's organized bacterial layers [think of a torte [14-layer] cake that someone has stirred with a knife.]
They are particularly not good with a mandarin or scooter in the tank [pod competition unless you have a huge refugium.]
The diamond goby is a great fish and neat for really big tanks: I'd say honestly, if you don't mind a little sand kickup and have a huge tank with a lot of sandbed.

If you're under 100g and like the sandsifters just because they're cute, get a yellow watchman and his tiger pistol shrimp. They'll move sand enough. I have one in my 54, and they're just about right for that tank.

If you're under 40, I'd say a watchman WITHOUT the pistol shrimp, because he'll be about right.

If you're 20 or under, I'd say just get Nassarius snails: they immediately dive under the sandbed and don't resurface unless there's something like raw shrimp to attract them. They're so slimy they can't even climb the glass. But they're great subsurface cleaners. THey do NOT eat algae: just meat, and crud.

Re fighting conches: good, but limit 1 per 50 gallons, in a well-established sandbed. Another creature that tends to eat itself out of house and home, and will just die if the sandbed can't support it. Do not combine with tiger pistol: too much competition.

These are all safe ways to clean your sandbed. Think of it as a Place, where certain things live, move, and do a job. Ideally, it should have stable layers over most of its extent, it should be disturbed only a few inches at a time, and sand-dwellers and small-scale sand-sifters do this best.

If you have a diamond already, and he's eating prepared food, and you love him, keep him---but don't otherwise overload your tank with fish, because the sandbed isn't quite up to miracles with a diamond in an undersized tank.