Tetra TetraPond UV Pond Water Clarifier Replacement Bulb, 5 Watts, 5 W / 4

Make sure to replace every pond season - the bulb may continue to glow, but its effectiveness in killing algae diminishes. Convenient viewing window in our Pond Green Free UV Clarifier makes it easy to ensure the bulb is working. Replacement bulbs are available in four sizes: 5 watts for ponds up to 660 gallons; 9 watts for up to 1,800 gallons; 18 watts for up to 4,400 gallons; and 36 watts for up to 8,800 gallons. Tetra Pond Green Free UV Clarifier (not included) works to keep your pond clean, clear, and free of unsightly green algae. These dependable clarifiers use ultra violet light to destroy suspended green algae. As algae are pumped into the clarifier, they are exposed to ultra violet light that destroys the reproductive ability of single-celled algae. The dead algae are then pumped out of the Pond Green Free UV Clarifier, where they clump and are removed by your pond's filtration system. Removes heavy algae blooms (usually within 8 days) and keeps the pond algae-free long-term.