Self Cleaning Filter Media constantly moving around and rub against each other only letting the strongest nitrifying bacterla survive | Simply Hook up to an Air Pump and getting all the benefits of oxygen in the water and a super charged biofilter. | Oxygen Rich Water combined with strong nitrifying bacterla handle large amounts of ammonia and nitrite compare to other type of filter | Easy to Remove Intake Sponge provides additional physical filteration | Comes with Enough Media similiar to K1 micro will float at first and start tumbling in a few days,Perfect filter to fill with any other media you might want.