If your tank description is accurate, that you have a nano, I will only make 2 suggestions. Nassarus snails are sand burrowers and will nestle down into the sand bed with their snorkles stilcking out. They will move around in ther keeping the sand turned and aerated. My other suggestion would be a dragon goby, a small one. This fella will take in mouthfulls of sand and sift it out through its gills looking for hidden bits of food. My word of caution on the goby....they can be jumpers and you'd want to keep a cover on your tank. Also, if you are already at your max fish quota, you shouldn't add him to your small tank. Just my 2c