How to Build a Sand Filtration System for an Aquarium

The sand at the bottom of an aquarium is called the substrate. The substrate, once thought to be simply cosmetic, has become an important factor in the filtration of water and the maintenance of the ecological balance of the aquarium. Lining the tank bottom with a 3- to 5-inch sand substrate provides a place for animals to burrow, as well as a perpetual biological filtration system through which animal waste and other detritus is removed and harmful nitrate is converted to beneficial nitrogen gas.

Things You'll Need

  • Enough dry aragonite sand (particle size from .05mm to .2mm) to fill aquarium to between 3 to 5 inches deep
  • 10-gallon bucket
  • Sand-dwelling organisms
  • Frozen fish food
  • Dirty or unfiltered aquarium water
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Instructions

    • 1

      Rinse the sand by placing about two pounds in a bucket and running cold tap water through it, swirling the water and sand around the bucket with clean hands. Pour off excess water and remove any large sticks and other detritus.

    • 2

      Add sand to the aquarium bottom to a minimum depth of 3 inches and maximum depth of 5 inches. If also using live rock, add the rock before adding the sand. Slope the sand from the back to the front so that larger pieces of detritus can float to the front for easier removal.

    • 3

      Fill the aquarium with whatever water you are using. Set up filtering system, heating system and lighting system. Allow these systems to run for a few days to a week while monitoring water conditions until they reach the desired levels.

    • 4

      Populate the sand bed with organisms. Hundreds of species live in sand beds, such as copepods, brittle stars, bristle worms and amphipods, and a diverse population will assure effective filtration of a deep sand bed. In the beginning, feed the sand bed with frozen fish food, and add some dirty, unfiltered aquarium water bought from a reliable supplier to the tank. Once the aquarium ecosystem has been established, the waste from the other animals will provide sufficient nutrients for the sand bed organisms.

    • 5

      Add a few sand sifting organisms to keep the upper levels of the sand bed clean and moving. Keep this population low so that food is not kept from getting to the organisms at the lower levels.