How to connect a UV filter to a pond

Updated July 20, 2017

When owning a pond, you want to maintain it to be as healthy as possible. The addition of an ultraviolet filter will help control the pond's algae and bacterial population, leaving the waters healthy. Water passes through the UV filter by means of a pump and the UV light inside disrupts organisms that pass through. A UV filter is not meant to replace a traditional filter, but meant to work in conjunction with it, so do not remove your basket filter in favour of a UV clarifier.

Determine how much water is in your pond. The strength of the UV filter is based on how much water is in your pond.

Use the following table to determine what size UV filter you need.

Minimum Gallons Maximum Gallons UV Wattage

0 400 8-watt

400 800 15-watt

800 1500 25-watt

1500 2500 40-watt

2500 4000 65-watt

4000 5000 80-watt

5000 7000 120-watt

If your pond size is borderline, choose the higher wattage filter.

Decide whether you wish to mount the UV filter vertically or horizontally. Horizontally is generally preferred since it's easier to keep water inside the filter.

Mount the filter onto a flat, dry surface using either mounting brackets or plumbers' straps. These will most likely not be included with your filter, so purchase these ahead of time. Do not mount the UV filter on the ground or in any place water can puddle around it.

Install the UV filter after the basket filter on the return line. You may install the UV filter before the basket filter, but this increases the chance of debris breaking or getting caught in your the filter.

To fit the UV filter for installation, decipher what type of connectors are needed.

If you have hoses, attach barbs to the water flow in and out ports. Hoses should fit snuggly over the barbs and secured with hose clamps to prevent leakage.

If you have 2-inch slip fitted unit for an 8, 15, 25, 40, or 65 watt unit, use PVC glue to glue the existing PVC pipe to the in and out flow unions on the filter.

If you have a 2-inch or 3-inch fitter unit for any unit larger than those above, cut additional 2-inch PVC pipe into the length of 2-3/8 inch. Glue these onto the filter's in and out flow units and then glue to the existing PVC pipe used for the filtration system.

Make sure all pieces are secure, all glue is dry, the lamp is in place, and the UV filter is mounted securely before operating.

Unscrew the Davis connector located on top of the transformer cap so the transformer cap can spin freely.

Plug the lamp flush into the lamp-end connector before inserting the lamp into the unit. Be sure all connections are solid before lamp insertion as a partially connected lamp can cause damage to the unit.

Push the lamp carefully into the unit, taking extra caution to not insert at an angle. Inserting at even the smallest angle can crack the quartz covering.

Twist the transformer cap onto the quartz cap. Do not over tighten.

Tighten the Davis connector back onto the transformer cap to lock in place. Allow water to run for five minutes to check for any leaks before plugging.


Do not submerge your UV filter unless it specifically says you can. Most UV filters are not made to go under water, though they are usually waterproof.

Things You'll Need

  • Mounting brackets or plumber's straps
  • UV filter of choice
  • Pond
  • Hose (optional)
  • Hose clamps (optional)
  • Existing filtration system
  • Additional PVC pipe (optional)
  • PVC glue (optional)
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About the Author

Sara Welsh has been writing professionally since 2009. Her areas of interest and writing expertise lie in the arts industry and she has published work for online publications such as Real TV Addict, Digigasms and Robodustrial. She holds a Bachelor of Music in music with elective studies in theater from the Shenandoah Conservatory.