Anjon Manufacturing CC-1200 Completely Clear 1200 Submersible Filter 9 Watt UV Clarifier: Eliminates green water by sterilizing suspended, free floating algae Zeolite Crystals: Zeolite reduces harmful ammonia in your Koi pond, creating a cleaner and healthier environment for your Koi and goldfish Built in Diverter Valve: Water flows to the fountain head or divert some to a pondside spitter 525 GPH Pump: Extremely energy efficient magnetic drive pump runs for pennies a day Bio Balls: Versatile and compact, the unique shape dramatically increases the surface area in your filter to colonize beneficial bacteria