OASE BioSmart 1600 Pond Filter Innovative Flow-Through filter design provides maximum oxygenation. BioSmart UVC 1600 is suitable for ponds up to 1,600 gallons (with no fish). High-surface area filter foams provide exceptional biological filtration capability. Distinct filter zones promote the settlement of a variety of beneficial bacterial responsible for different phases of the nitrogen cycle, which increases the conversion of harmful ammonia in your pond . Advance features include the built-in cleaning indicator notifies you when the filter needs cleaned and water temperature display tells you the water temperature at all times.