The Aqua Nova NSF-R series round sponge filters are air-powered internal filters, ideal for shrimp tanks, fry tanks, and aquariums with sensitive or small fish. Thanks to their soft flow and silent operation, they are perfect for setups that require gentle filtration and biological stability. An external air pump (not included) directs air through the central uplift tube, drawing water through the fine sponge. Suspended particles are captured mechanically, while the sponge provides a large surface area for beneficial bacteria to colonize and biologically clean the water. These compact, fully submersible filters are easy to position and maintain, making them a great choice for any freshwater aquarium.Aqua Nova Sponge Filter NSF-R+ air-powered internal sponge filter with round shape+ combines mechanical and biological filtration+ ideal for shrimp, fry, and sensitive fish+ gentle flow, quiet operation+ easy to clean and maintain+ flexible positioning within the tank+ staple base, filter d