Replacement 20 Watt 4 Pin UV tube. The 20 Watt 4 pin UV lamp fits the Laguna Pressure Flo Filter PF8000. These linear tubes are energy efficient and are extremely effective at helping to clear the algae in your pond. The bulbs also have ozone friendly ceramic ends, providing more efficient UV output To ensure the effective use of your Laguna Filter, its is recommended that you change the bulb in the unit every 6 - 12 months. Specifications 20 Watt Will fit Laguna Pressure Flo Filter PF8000 Dimensions: 365mm Please note - these bulbs are intended for use in filters and clarifiers and should not be used as lighting.