JennM;910458 wrote: Sleeper gobies (Diamondback, Goldenhead, Dragon, Tiger Sleeper etc.,) are hit and miss - some sift close to the bottom, others like to bury stuff or bring the sand up into the water column and "snow" it down on everything, such as what you're experiencing.
Conchs are good, as mentioned - they exhibit odd behavior in that they'll move around for several days, then they will rest for several days, so it's not unusual for them to be still for days at a time, making one wonder if they've perished.
Another good choice for keeping the sand turned, are Nassarius snails. I personally prefer the ones from Tonga - they're a bit bigger than the Caribbean ones. They're omnivores - they'll eat meaty food/waste as well as algae or whatnot. When you introduce prepared foods into the tank, they will come up out of the sand like submarines with their periscopes up (they have a long, soft proboscis).
How deep is your substrate? If it's shallow (2" or less), it should be vacuumed regularly when doing water changes, in addition to having creatures that help keep the sand turned.
Jenn