Pondmaster® 40 WATT UV Clarifier. For ponds up to 3000 gallons. Recommended to use with a pump from 2400 gallons per hour. For example, the Praefecta Pond Pump 2400 is suitable. Includes transformer and 18 cord. Can be used submersed or on the shore of your water garden pool. Has a Blue Glowing Monitor Halo Ring® that will let you know if the unit is on. Comes with a 1-1/2 barbed fitting. Size: 3 dia x 24 Long. The unique vortex design of the UV clarifier increases water contact time with the UV light, while the slim diameter lamp allows the water to get closer to the UV rays, see in the image.