Laguna PF4000 36W Pressure Flo Filter Features: 3 Step Filtration System: Mechanical, biological and integrated UV filtration work in unison to provide clean and clear pond water New Energy efficient UV bulbs. New four prong bulbs are simple to install and provide powerful UV sterilization to prevent and eliminate green water Premium European Construction and Patented Backwash Cleaning System Combine with a Laguna Max-Flo pump for the ultimate combination in filtration and performance Pressure-Flo 4000 UVC is for ponds up to 4000 gallons and comes complete with a 36-watt UV lamp, 5 filter foams and 4800 g of Bio-Lava Rock