Multi-layer Fine Sponge: Provide mechanical and biological filtration and trap debris or wastes without sucking up your fish. Keep fish tanks crystal clear and healthy. Further Cleaning: The bottom gravels absorb excess damaging substances and release trace elements. And the ceramic rings can cultivate beneficial substances. Always keep water fresh. For 30 Gal Tanks: Measure 3.1" R x 3.3" H. Fit for 10-30 gallon fish tanks. You can change the sponge sequence at will and customize the filter materials according to the breeding density of the fish. Quiet Aeration: Air powered and cause no disturbance to your daily life. The outlet tubing is freely adjustable in height and the duck-billed outlet port brings more bubbles to promote oxygen circulation. Easy to Clean: The filter can be easily detached for cleaning. Rinse the sponges every 2 to 4 weeks with aquarium water ONLY. Avoid soaking or washing them in tap water! Replace the white sponge every 2-3 months! Product description Pawfly specializes in all must-haves of aquarium accessories such as air pumps, air stones, sponge filters, fish nets, cleaning brushes and other accessories to set up your aquariums. Sponge Filter for 30 Gal Tanks With 3-layer fine sponges, lots of gravels and ceramic rings to clear up impurities and promote air diffusion, it provides effective filtration and brings higher dissolved oxygen rate to keep water clean and healthy. It features fine cleaning effect, quietness and easy maintenance. Ideal for aeration in 10 to 30 gallon fish tanks. Fit for shrimp, fry and various ornamental fish like betta, discus, guppy and goldfish. Medium size: 3.1" R x 3.3" H Up to 30 gallon tanks Multi-layer fine sponge Natural gravels ceramic rings Fit in the corner nicely Quiet easy to be cleaned Make tanks crystal clear Soft Fine Sponges 3-layersoft sponge material has high air/water permeability. The sponge sequence can be changed to meet your preference. Gravels Ceramic Rings Effectively absorb harmful substances and cultivate beneficial microorganisms. They can be replaced with your customized materials. Up to 30 Gallons Medium size ? 3.1 inches in radius and 3.3 inches in height. Work great in 10 to 30 gallon fish tanks or aquariums. Corner Shape Larger exposed surface area for more air exchange. Fit nicely in the corner to make way for fish?s swimming or tank decoration. Air Powered The air chamber produces tiny bubbles which greatly increase the oxygen solubility of water. Air Pump Not Included. Easy to Clean Detachable design allows you to easily take it apart for cleaning or replacement. Rinse and squeeze the sponges with aquarium water ONLY.