Penn-Plax Cascade Nano-Sponge, The Biological Filtering System Aquariums Fry (Powered)
Fine porous sponge maximizes colonization of beneficial bacteria to help keep water crystal-clear. Simply set-up by rinsing the sponges and then suctioning the filter to the side of your tank with the two included suction cups. The two sponges are designed to house beneficial bacteria without allowing baby fish, shrimp, or other underwater creatures get sucked in. Safe for freshwater and saltwater tanks.