The Dymax eZ Filter is an efficient and well performing internal filter that will help maintain proper aquarium health. Filter media within the filter have a high surface area, making it perfect for beneficial bacteria to colonize and thrive. The eZ Filter has all its media separated with a filter basket and includes white wool (mechanical filtration), activated carbon (chemical filtration), and biological sponge (biological filter). Filter media should be cleaned or replaced regularly to maintain optimum performance.