Learn the science that keeps aquarium water clean, oxygenated, and stable.
Fish live directly in the water that surrounds them, so water quality is one of the most important parts of an aquarium. Filters, beneficial bacteria, oxygen, temperature control, and careful observation all work together.
Filters move water and can remove particles while supporting useful microorganisms.
Learn MoreSome bacteria help process waste into less harmful forms.
Learn MoreFish and many other aquarium organisms need dissolved oxygen.
Learn MoreAquarium species are adapted to particular temperature ranges.
Learn MoreTests give aquarium keepers information that cannot be seen just by looking at the water.
Learn MoreRegular care prevents waste and debris from building up over time.
Learn MoreAquarium filters usually do more than catch visible dirt. Water movement can carry debris to filter material, improve circulation, and provide oxygen-rich surfaces where helpful bacteria grow. Different filter designs work in different ways, but the goal is to help keep the aquarium environment stable and healthy.
Fish and other aquarium animals produce waste. Helpful bacteria living on filter material, gravel, rocks, and other wet surfaces take part in the nitrogen cycle by changing certain waste compounds into other forms. A healthy biological filter is one reason a new aquarium needs time to become established.
Oxygen enters aquarium water at the surface and can be distributed by water movement. Plants also release oxygen when they photosynthesize in the light. Warm water generally holds less dissolved oxygen than cooler water, and crowded tanks can use oxygen quickly, so good circulation and appropriate stocking are important.
A tropical stream fish and a cool-water fish may not be comfortable at the same temperature. Stable temperature matters because sudden changes can stress aquatic animals. Aquariums use thermometers and, when needed, heating or cooling equipment to keep conditions appropriate for the species.
Clear water is not always healthy water. Aquarium tests can measure properties such as acidity, dissolved waste compounds, or salinity in marine systems. The purpose of testing is to understand what is happening in the aquarium and spot developing problems before they become serious.
Aquariums are closed systems, so materials that would be carried away in a river or ocean can remain in the tank. Routine maintenance may include removing debris, checking equipment, observing animals, and replacing part of the water with suitable clean water. Safe aquarium care follows product directions and adult supervision where equipment or chemicals are involved.