How to Build a Sand-Filtration System for a Freshwater Aquarium

Put two pounds of sand at a time in a bucket and rinse with cold tap water. Drain excess water and remove any sticks or stones. A 10-gallon tank needs 10 pounds of sand to create a layer that is one-inch deep. Since you want at least three inches of sand for a good filtration system, you need three pounds of sand for each gallon the tank holds. For example, a 30-gallon tank needs 90 pounds of sand.

Place the clean, rinsed sand on the aquarium bottom. The sand should be between three and five inches deep. If your aquarium setup also uses rocks, put these in the tank before adding the sand. Slope the sand slightly from front to back to aid in tank cleaning.

Fill the aquarium with water.

Set up your filter, light, and heating systems.

Add organisms such as copepods, brittle stars, bristle worms and amphipods to the sand bed. A diverse population of organisms ensures that the sand-filtration system is most effective.

Feed the sand bed with frozen fish food and add some unfiltered tank water. Unfiltered or dirty tank water is essentially water from a tank that needs to be changed and has the necessary bacteria to help jump-start your sand-filtration system. Both the frozen fish food and the unfiltered tank water can be procured from a pet shop. After adding the organisms, food, and dirty water, the aquarium ecosystem will slowly stabilize on its own to the point that waste from the fish will provide the necessary nutrients for the organisms living in the sand bed.

Add sand-sifting organisms to the sand bed. These organisms help the sand bed stay clean. Keep the population low so food will still make it to the other organisms at the lower levels of the sand bed.

Allow the tank to "cycle" for at least two weeks. Test your water with a kit from the pet store to make sure the levels are appropriate for the type of fish you are introducing into the tank system.