Aquarium filter
Filters remove waste and support life in closed aquarium systems.
An aquarium filter is essential for both freshwater and saltwater tanks. It works by pulling out solid waste and dissolved chemical impurities from the water, which makes upkeep easier. Because a fish tank is a small, sealed-off body of water—unlike a fish’s natural habitat—filtration is necessary to keep the inhabitants alive.
Fish produce waste through their droppings and breathing. Uneaten food, dead plants, and dead fish also add to the mess. These waste products build up in the tank and pollute the water. As pollution increases, the health of the tank suffers, so removing that contamination becomes crucial. Filtration is a common way to keep an aquarium healthy.
Managing the nitrogen cycle is key to a successful tank. Fish waste and rotting organic matter release ammonia, which is very poisonous to fish. Bacteria then convert this ammonia into nitrites, which are slightly less toxic, and then into nitrates, which are much safer. In nature, plants use nitrates as fertilizer, and this happens to some degree in a tank with live plants.
However, an aquarium is an imperfect copy of the natural world. Tanks are usually much more crowded with fish than a natural environment, which means more ammonia is produced in a small space. The bacteria that break down ammonia into nitrite, called *Nitrosomonas*, live on the surfaces of everything inside the tank. The bacteria that turn nitrite into nitrate are *Nitrospira* and *Nitrobacter*. A biological filter is often just a porous sponge that gives these bacteria a much larger surface area to grow on. These bacterial colonies take several weeks to form, and if fish are added too quickly, the tank can suffer from “new tank syndrome.” Some filter systems include bacteria that can turn nitrates into nitrogen gas.
A buildup of toxic ammonia from decaying waste is the main cause of fish death in new, poorly maintained, or overcrowded tanks. In an aquarium, the nitrogen cycle usually stops at nitrates. To keep nitrate levels from becoming dangerous, regular partial water changes are needed to remove the nitrates and add fresh water.
Mechanical filtration removes solid particles from the water, such as uneaten food, feces, or bits of plants and algae. This is usually done by pushing water through a sieve-like material that traps the particles.
- Ammonia to nitrite bacteria
- Nitrosomonas
- Nitrite to nitrate bacteria
- Nitrospira and Nitrobacter
- New tank syndrome formation time
- several weeks
- Activated carbon regeneration temperatur
- 500–900 °C (932–1,652 °F)
Lore & Background
Aquarium filters remove waste from excrement, respiration, uneaten food, and dead organisms. Contamination removal is critical as it rises, and filtration is a common method for maintaining healthy aquaria. Biological filtration manages the nitrogen cycle: bacteria like Nitrosomonas convert toxic ammonia to nitrite, and Nitrospira and Nitrobacter convert nitrite to less toxic nitrate. These bacteria colonize surfaces such as porous sponges, which provide enlarged surface area. Bacterial colonies take several weeks to form, during which the aquarium is vulnerable to 'new tank syndrome' if stocked too quickly. Accumulation of toxic ammonia from decomposing wastes is the largest cause of fish mortality in new, poorly maintained, or overloaded aquariums. Regular partial water changes are required to remove nitrates, as the nitrogen cycle effectively ends with nitrate production in the artificial environment.
Reader's Guide
The article describes aquarium filters as essential for waste removal and life support in closed systems. Mechanical filtration removes particulate matter like uneaten food and feces by passing water through a sieve; solid wastes must be physically removed from the filter to prevent decay. Chemical filtration, including activated carbon and foam fractionation, removes dissolved wastes; plants can also extract dissolved chemicals. Sterilization via ultraviolet light or ozone is a less common filtration need. Numerous materials serve as filter media, including synthetic wools, sponges, ceramics, sintered glass, and igneous gravels. Activated carbon adsorbs toxins on its porous surface and must be replaced regularly to avoid re-releasing harmful doses. Power filters (HOB) are common, offering media selection and easy cleaning but can cause excessive flow and noise. Canister filters provide greater media volume and flexibility, with pumps insensitive to height differences due to counterbalancing siphons. The article emphasizes that biological filtration is inherent in most filters due to bacterial colonization, and that proper management of the nitrogen cycle is vital.
Did You Know?
- The bacteria Nitrosomonas convert ammonia to nitrite, while Nitrospira and Nitrobacter convert nitrite to nitrate.
- Activated carbon can be regenerated at temperatures of 500–900 °C, but for aquarists, replacing it is simple and inexpensive.
- Canister filters use counterbalancing siphons so the pump does not have to lift water back to the aquarium.
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