A sump filter is a type of filtration system commonly used in aquariums and ponds. It is typically located in a separate container or sump area, where water is collected and filtered before being returned to the main tank. This setup helps maintain water quality by removing debris, toxins, and other impurities. Sump filters often utilize various filtration media, such as foam, activated carbon, or bio-balls, to effectively clean the water. They can also provide additional benefits, like increasing water circulation and allowing for the installation of heaters or protein skimmers, enhancing the overall health of aquatic environments.