Pondmaster® 05425 CPF 500 Series with 13W UV Clarifier 500 gal. Pondmaster CPF Series Pressurized Filters are ideal filtering systems for small to medium ponds and water features. They've been designed to reduce required maintenance while establishing a healthy environment for fish and aquatic plants. This integrated system can be conveniently located in or near a pond or patio container. The UV Clarifier models help clear ponds of green water algae.