What Kind of Filter Should I Use for a Salt Water Aquarium?

Salt water fish and invertebrate creatures, such as sponges and corals, require a stable and pollution-free living environment. These living animals, however, continually deposit metabolic waste into the aquarium and thereby lower the water quality. Filters are used to remove toxic waste material and to ensure optimal living conditions for the aquarium inhabitants.

  1. Protein Skimmer

    • Protein skimmers, which are also known as foam fractionators, are filters that remove waste material from the water before it begins to break down. These filters typically consist of a long reaction tube, through which very fine bubbles are passed. The bubbles are created either by a wooden stone which is connected to a vibrator pump, or by a venturi feature. Molecules of fish urine and other proteins adhere to the bubbles and are removed from the aquarium water, once these bubbles form stable foam at the water surface. This foam pushes up into a collection cup, which is emptied and cleaned as necessary.

    Biological Filter

    • The porous filter material within these filters is covered by cultures of beneficial bacteria. Oxygen-loving or aerobic bacteria species develop on the outer surface of this material, which is exposed to high water flow and oxygen levels. Those species of bacteria which can only survive in an oxygen depleted environment grow within the porous filter material. Together, these bacteria break down toxic metabolic waste in the aquarium water.

    Ultraviolet Sterilizer

    • This specialized filter consists of a hollow cylinder which contains an ultraviolet light source. Unicellular algae, bacteria and disease-producing organisms which are carried in aquarium water, are destroyed when they pass over the ultraviolet bulb. This filter is therefore capable of not only keeping marine water clean, but of controlling disease outbreaks. Ultraviolet filters are best positioned after the mechanical filter, which will remove larger pieces of detritus and debris, before the water is exposed to the ultraviolet light source.

    Diatom Filter

    • Diatomaceous filters remove extremely small particles of detritus from aquarium water. Diatomaceous earth is made up of the skeletons of diatoms and is capable of trapping microscopic particles. Free-swimming pathogens or disease-producing organisms are also removed from aquarium water by these filters. Diatom filters need not run continually and are normally used when the water is cloudy or during an outbreak of disease.

    Chemical Filter

    • Chemical filter material removes toxins from the aquarium water. Activated carbon is the most commonly used chemical filter material. Activated carbon traps and holds molecules of waste, which is removed from the aquarium, once the carbon is disposed of. It is important to replace activated carbon on a monthly basis, to prevent it leaching toxic waste back into the aquarium water.