The ocean is constantly recycling consumed nutrients. In a saltwater aquarium, there are biological, mechanical, and chemical filtration that can be used to maintain the balance of an ecosystem. These three main forms of filtration have many subcategories and will not be fully covered in this topic.


Biological Many new hobbyist hear the term “live rock” and wonder what live rock means. The term live rock doesn’t mean that the rock is alive but rather refers to all the macro and microscopic organisms that are on and all over the rock. These organisms are very important for the health of a reef. Rock contains a balance of bacteria and organisms that maintain the equilibrium of a reef. Each of these organisms compete and form a equilibrium that helps buffer a reefs nutrients and waste.

In a saltwater aquarium, biological filtration is, in my opinion, the most important factor in the health of an artificial reef. A correct amount of biological filtration as well as quality will ensure the longevity of a saltwater aquarium setup. Some aquariums employ solely this form of filtration with some water movement so the rock constantly receives nutrients from all over the tank.

Other forms of biological filtration are employed such as bioballs, biosocks and biosurfaces. The concept is the same in which the bacteria colonize these surfaces and form a balance that aids in the health of a saltwater aquarium.

Mechanical There are several mechanical ways of removing excess nutrients and import fresh nutrients. One common method is removing saltwater and replacing it with new fresh saltwater. This guarantees that nutrients are exported out of the system and fresh saltwater is imported in the system. If done regularly an equilibrium will be reached and excess unwanted nutrients can be controlled.

Other methods of mechanical filtration include skimmers and macro algae removal. Skimmers are equipment that uses the property of surface tension to separate dissolved molecules from the water column. This produces a light to dark green liquid that is collected and discarded. There is a wide selection of skimmers for larger systems and a handful for very small systems. On the other hand macro algae removal is widely used in small systems as well as larger systems. In a separate compartment of the aquarium algae is grown and then manually removed in a consistent basis. Because algae are plants, and require nitrate and other dissolved molecules to grow, it is believe by removing a part of the macro algae these nutrients are also being exported out of the system.

Chemical There is a wide range of chemicals used in small and large saltwater aquariums. The most common ones encountered are carbon and phosphate removers. Carbon is used to decrease the nitrate that is present in the aquarium and required to be replaced regularly to maintain it efficiency. Phosphate removers are chemical media that binds phosphate allowing the phosphate to drop.

It is important to note that saltwater aquariums still require some form of nutrients to thrive. There are some hobbyist that believe that a very clean system is the best growing conditions for corals while other state a more heavily feed system with lots of nutrients is the way to go. In reality it really depends on what type of corals you plan on keeping, and also the type of maintenance that will be provided for the aquarium. In my opinion a well balanced and planned feeding regimen, will provided a very suitable growing condition for a wide variety of coral and organisms