SOBO Hang-On-Filters combined with 3-in-1 filtration system- provides a healthy and clean aquatic environment that your aquarium needs. Mechanical Filtration : To remove debris, dirt, particles such as uneaten food, bits of plants, fish wastes, etc. from the water. Chemical Filtration : Premium Activated Carbon removes compounds that causes odors, discoloration and impurities of the water. Biological Filtration : To provide for the growth of a colony of beneficial bacteria that will remove harmful Toxins (Ammonia, Nitrates) in the water.