Hello. I bought an 8 gallon nano about a year ago. I was not and still am not very familiar with saltwater tanks so I thought that the nano would be a good start. I asked the person at my local fish store if I needed to do anything similar to vacuuming the rocks at the bottom of a freshwater tank, with the sand in a salt water tank. She said no, that I just leave the sand. However, a year later the sand has become somewhat dirty and kind of takes away from the appeal of a nice little saltwater tank. I bought a "cleaning crew" with the snails and crabs but the ones that borough themselves under the sand don't seem to be doing much to mix it around and keep the sand clean. What should I do? Any suggestions? Please let me know, I would really appreciate it!