Sand "is just yucky looking."
What to do about it?
* Warning: This post is a little different than the above responses to your question. I like to use a plethora of marine organisms that support/eat each other in an interconnected ecological system, but I stay away from some organisms mentioned above. The question is a good one that many hobbyists have had at one time or another.
What is the water flow in your tank?
Good flow can help keep the sand clear and clean. The positioning of powerheads makes a big difference. I recommend that powerheads be positioned down low near or on the sand pushing water up as a stream to make the surface water roll(see image below). This oxygenates the water(gas exchange) making pH stay up where it is supposed to be and encourages waste oxidation(Redox). The health and cleanliness of a tank can be vastly improved by adjusting water flow in this way.
Do you manually stir different areas of your LS bed periodically?
This procedure, using a stick, a large syringe as mentioned already, or your hand, is an excellent way to feed invertebrates like coral and shrimp, while at the same time turning over the clean sand that lies just below the surface. Yes, the detritus in the LS is great coral food.
Are there any worms in the LS?
Spaghetti Worms are awesome sand cleaners. When looking at the cross section of the sand bed through the aquarium glass, if you can see worm trails in the sand that's a good thing. That is evidence of good biofiltration.
Are there bugs living in the LS?
Bugs such as Amphipods and Copepods are also good at keeping the sand cleaner.
Many of the bugs and worms that we like to encourage as part of the biofiltration are likewise producers of natural live food for our coral and fish. As a side benefite they are actually very good at cleaning the yuck off the sand.
I give free Live Sand to hobbyists so they can establish this natural cleaning ecology in their reef aquariums.
Is there any Macroalgae in the display?
I find that algae is the quintessential cleaner. Besides its well known ability to eat pollution like crazy, it provides an ideal environment for bugs to live, reproduce and eat detritus. The bugs come out at night and travel the sand looking for food. This cleans the sand. One tank in my system has a bottom growth of Blade Caulerpa which makes it look like a grassy flat.
Hermit Crabs are excellent at disturbing detritus and helping keep the top sand clean. Too many Hermits can get awful hungry and start eating Snails so it's important to achieve the right balance. I recommend about one Hermit for every three Snails
Sand Sifting Cucumbers are awesome because they generally clean just the top layer of sand, leaving the lower layers of sand to do its very important main job; Biological Filtration. SSCucumbers can get pretty large and eventually cause havoc to the sand bed so I don't recommend them for tanks under 50 gals or recommend trading a large one for a smaller one when they get to that point.
On the other hand, Sand Sifting Stars destroy the biofiltration,
eating/decimating the in-fauna and flora so completely that the sand can no longer accomplish its main function as the major part of reef aquarium biofiltration. I only recommend SSStars for a deep cleaning of an old dirty sand bed and to be removed after 2-4 months; possibly replaced with a Sand Sifting Cucumber.
I dislike what I have come to call "sand throwing" fishes. They can create a real mess by throwing sand all over the place, even covering sand dwelling coral like plate and brain coral. They also decimate the in-fauna and flora of the LS. Some Jawfish aren't so bad like the ones DLindquist mentioned.
I don't know why, but I have never used Conch Snails. I guess it's because I never needed them or because they also moderately eat the LS in-fauna and flora. The above points have always accomplished the job for me.
Aloha,
Mark
808-345-1049 call/text before coming over for a visit to get free LS and Macroalgae
750 E Lakepoint Dr. #4V Murray
Edited by Mark Peterson - May 05 2014 at 9:29am