Conchs and nassarius are the best, but I doubt they will keep it fully clean. They will help a lot though. I had conches and they did the most however a crab got the best of them. My nassarius are cool to, however they only get the top of the sand when food is added to the tank, because that seems to be the only time they come out. The conch on the other had went in and out of the sand all the time.