Biological filtration is a process used in aquariums and wastewater treatment systems to remove harmful substances from water. It relies on beneficial microorganisms, such as bacteria, that break down organic waste and convert toxic compounds like ammonia into less harmful substances. This natural process helps maintain a healthy environment for aquatic life. In an aquarium, biological filtration is often achieved through the use of filter media, such as bio-balls or ceramic rings, which provide a surface for bacteria to grow. Regular maintenance and monitoring of water quality are essential to ensure the effectiveness of biological filtration and the overall health of the ecosystem.