Beach or silica sand gives a natural look to a seawater aquarium. The individual particles are relatively small and smooth, allowing burrowing fish, such as wrasse, to dig into the substrate without damaging their bodies. Beach sand also represents a natural and acceptable substrate for starfish and sea urchins to crawl over and to feed from. Although aquarium sand is sold by most aquarium dealers, you can collect and prepare your own beach sand.
Rinse your hands thoroughly under warm water to remove any soap residue and natural body oils, both of which are detrimental in saltwater aquariums.
Place two handfuls of beach sand into a 5-gallon plastic bucket. It is far easier to clean small amounts of beach sand than trying to clean the whole batch at once.
Place the 5-gallon bucket under a tap and half fill the bucket with water.
Swirl the beach sand around in the bucket for a minute and then pour off the dirty water. Be careful not to pour out beach sand with the water.
Half fill the bucket once again. Open the tap fully, in order to disturb the sand as much as possible. Place one of your hands into the bucket and agitate the sand. Pour off the dirty water.
Continue to flush the beach sand with tap water until the water that is poured out of the bucket is clear and visually clean.
Add sufficient boiling water to the bucket to cover the beach sand. Natural seawater contains pathogens or disease-producing organisms that may be present on the beach sand if you collected it close to the water's edge or during high tide.
Pour off the water once it has cooled and rinse the beach sand once more to remove any dead plankton, bacteria and pathogens that were destroyed by the boiling water.
Fill a long-handled aquarium net with the clean beach sand and place the net carefully into the aquarium. Hold the net just above the aquarium floor and, using a long plastic aquarium tongs, take hold of the bottom of the net and gently tip the beach sand out.
Continue to wash and add beach sand until you have sufficient substrate in your aquarium.
Slope the beach sand gently from the rear of the aquarium to the front so that detritus and debris can work to the front glass plane, where it can easily be seen and removed.