Mechanical and biological filtration system in one unit The filter cart can be changed and displayed as a complete single piece. Easy setup, easy maintenance, and efficient performance Ideal for freshwater and saltwater aquariums. It is a mechanical and biological filtration system. Special carbon cart for water purification, odor removal, and providing a housing chamber for biological bacteria. The bio cart enhances biological filtration and ensures optimal colonization of oxidizing bacteria. Easy to use, just fill with water and plug it in. Easy maintenance. Replace the new carbon cart every two months for best results.