Notice that many of the common aquarium medications including antibiotics are removed by activated carbon and therefore should not be used when treating the aquarium for disease. Recently many other types of chemical filter materials, called zeolites, have been developed to remove specific compounds such as nitrate and phosphate. Generally a fish only marine aquarium has no need of these types of filtration but can be used in a mini-reef setup. Other filtration - Foam Fractionators, or protein skimmers , work by passing a large stream of small bubbles through a column of aquarium water. One of the drawbacks to skimmers is that they remove trace elements and iodine which, if needed by any of the aquarium inhabitants, must be replaced periodically.
Ultraviolet sterilization works by passing water through ultraviolet light.
If the water is exposed long enough, at a high enough concentration of light, bacteria, algae, and parasites can be destroyed by the light. This is a somewhat controversial filtration method that some people swear by and others dismiss as ineffective. Ozone can be passed through aquarium water to oxidize all forms of organic pollutants and kill many of the same organisms that ultraviolet radiation does. According do Julian Spring and J. Charles Delbeek in their book The Reef Aquarium Volume Two, ozone is useful mainly in large public aquariums to keep the water from coloring. They also state that aquariums that use ozone generally maintain a slightly higher nitrate level.