The sera Internal Sponge Filter is a air driven filter that is ideal for utility systems such as quarantine/hospital and breeding/grow-out setups. These filters operate by air drawing in water through the sponges which act as mechanical and biological filtration and up and out of the outflow tube. The elbow at the top allows for directional flow and reduces splashing and bubble noise compared to traditional sponge filters.  
 
NOTE: For display systems we strongly recommend Hang-on-Back, Internal Power Filters or Canister Filters depending on size and bio load.