Pressurized Biological Pond FilterCrystal Clear Water for Healthy Fish & Ponds! The VIVOHOME Pressurized Biological Pond Filter combines mechanical and UV filtration to keep ponds up to 1,600 gallons (ornamental) or 800 gallons (koi) clean and algae free. With a 13W UV clarifier, 4 stage sponge media, and easy cleaning crank handle, its the ultimate all in one filtration solution. Key Features: Powerful 1580GPH Flow Handles large ponds with ease. UV Sterilization 13W bulb kills algae