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40 Watt PondMaster UV Clarifier

Ultraviolet clarifiers eliminate green water.

  • To Clear Green Water (Clarifier) for ponds up to 6000 gallons used at flow rates up to 2400 GPH.
  • To kill many bacteria (Sterilizer) for ponds up to 2000 gallons used at flow rates up to 1200 GPH.
  • Can be used submerged (recommended) or outside the pond.
  • Glowing Halo Ring visible from any angle shows it's working.
  • 9000 hour long life for lamp.
  • 18' grounded power cord.
  • 23-1/2" long
  • 4" diameter
  • Manufacturer's limited 1 year warranty.
  • 1-1/2" MPT inlet/outlet, also includes elbows for each that adapt to 1-1/2" barbed fittings.

40 Watt PondMaster UV Clarifier

~Price $282.00 40 Watt Clarifier for ponds up to 6,000 gallons

UV Clarifier Details

Care and Operating Instructions for Pondmaster UV Clarifiers

Ultraviolet light is a wavelength of light which inhibits algae from reproducing by damaging its DNA. It also kills parasites in the water. UV light does not harm string algae which clings to the sides of ponds and therefore does not travel through the filter and UV rays. Barley wheat is a natural solution to that menace.

The quartz sleeve is not installed and is located in a separate box inside the main box. To install the sleeve, insert the round end into the main body until the rubber ring is all the way down into the main body. A flange will prevent the ring from going any further. It will rest against the main body. To remove the sleeve for cleaning, take a kitchen knife or thin screw driver and pry between the rubber flange and main body.(See photo No. 1)

The UV lamp is not installed and is located in a separate box inside the main box. To install the lamp, unscrew the transformer from the main body. Align the center slot and pins with the mating connector that is inside the transformer.

Push the lamp down firmly. Slide the lamp and transformer into the quartz sleeve and screw the transformer onto the main body. Do not over-tighten the transformer when screwing it to the main body. Lightly hand tighten it.(See Photo Nos. 2, 3, & 4).

Always turn off the power before handling or servicing the unit.

Never look at the lamp rays.

Please note the Halo rings transmit visible light only, which is safe to look at. This indicates the unit is working. Remember the lamp will produce visible light long after it has stopped producing effective UV light.


This unit is for seasonal use only. It should not be used in freezing conditions because the quartz tube will crack, exposing live electrical current to the water. If the unit is dropped do not use it. Unplug it first and inspect the quartz sleeve for breakage or small cracks.

Electrical Precautions

Always use a properly grounded outlet. Do not immerse plug in water. Do Not Reach Into Water To Remove Plug. Turn Off Circuit First.A "drip loop" should be provided. The "drip loop" is a loop in the cord below the level of the receptacle or plug that prevents water from traveling along the cord.

The national Electric Code requires that a ground fault circuit interrupter (CGFCI) be installed in the branch circuit supplying fountain or pond equipment. Your dealer can supply GFCI units. Never remove ground pin from plug.

WARNING: for your protection always unplug the unit from its power source before installing or servicing. Should the halo rings indicate the unit is not working do not reach, remove or disassemble before you disconnect power.

General Information

For best results, the total amount of water in the pond should pass through the Ultraviolet light every 2.5 to 3 hours. Pumping water too fast will shorten the ‘dwell time’ - the time that the water in the unit is exposed to the ultraviolet rays.

The Pondmaster Ultraviolet Clarifier/Sterilizer is the only submersible unit on the market. It can also be used outside the pond when connected with tubing.

The lamp has a life of 9,000 hours, which means if you use the light continuously for 6 months per year, in most regions of the country, it will last two years. The unit should remain on 24 hours a day throughout the season.

Regardless what the manufacturer says, for the best possible performance, we recommend that the lamp be replaced every 6 months (or at the beginning of each pond season) because it slowly degrades.

Remember the lamp will produce visible light long after it has stopped producing the UV wavelength. The quartz sleeve should be cleaned periodically due to dirt or lime scale build-up since this will block the UV light and reduce efficiency. Clean the quartz tube with vinegar and a scrub pad. It is not a bad idea to replace the tube when you replace the bulb. It helps to lubricate the black gasket with silicone grease when reinstalling the quartz sleeve.

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E.G. Danner Mfg. Inc. will repair or replace any unit found to be defective within one year of original purchase. Cutting or altering cord voids any warranty consideration. For warranty repair return only the part that is defective to our factory.

Information provided by Danner Mfg., Inc. Maker of Pondmaster UV Clarifier/ Sterilizers

What is the difference between an ultraviolet sterilizer and an ultraviolet clarifier?

Actually, there is not a difference in the units themselves, the difference is in the ratings provided for the appropriate pond size and flow rate. By following UV sterilizer ratings the pond should have clear water despite most other conditions and the UV will also be more effective against controlling microscopic pathogens.

A UV clarifier rating typically means that you may not have crystal clear water all the way to the bottom. It also assumes that the pond has good plant coverage (greated than 50%) and adequate biological filtration. When following UV clarifier ratings it is a good idea to oversize the UV to help ensure cleaner water.

Manufacturer Model Number: 02940
Made in China


I've used the 10 Watt PondMaster UV Clarifier for less than 1 year,and it works great for my pond setup! I installed this UV sterilizer submerged in-line between my submerged filter and submerged pump. My water was so green during installation I did it blind. Within 2 days the water was significantly clear. After one week crystal clear! And still working great after 1 month. I no longer have to treat pond with chemicals. My pond size is 1000 gals w/ flow rate of 1300+gph (1600gph rated pump). Pond size is 10 x 10 x 2ft. Knowing what I know now aboout UV sterilizers I would have bought before builing my pond. But, even so, it was a simple retro-fit which took less than 1 hour from box to pond.

Rick D
from Alabama

I have a pond 3’ x 15’ x 18’, a stream 2’ x 2’ x 30’ in length and a set of rapids with a water fall. The water was dark with a slight green color. I installed this unit in the second week of May. Four days and the stream was clearing so I could just make out the bottom and the pond was clear down to 1’ deep. After six days the water was clear to the bottom in both the pond and the stream. I was skeptical at first, but this product works. I may need a larger pump to meet the manufactures specs, mine is only 1300 GPH.

from Michigan

My experience was similar to the others. I installed the unit inline submerged between the submerged filter and pump. After 10 days my murky, dark water was crystal clear. It's hot and muggy in the Summer here in South Florida and algae is a big problem. This is the best $200 I've spent.

My 3000 gallon pond is 10 x 25 x 3 with a 4000 GPH pump feeding a waterfall. I also added a two outlet air bubbler, and the fish seem much more comfortable with the water temp being at 85 degrees. I feel much better about the health of my fish with this unit than adding chemicals constantly.

Gene S.
from Florida

I've used the 20 watt Pond Master Clarifier Over 3 years.

Best UV light ever on the market. Took care of green algae problem.

from Georgia

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