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Choosing a Pump for UV Clarifier or Pressure Filter

Choosing a Pump for UV Clarifier or Pressure Filter

There is nothing worse for a pond owner than seeing a water feature that has turned green. Green water is caused by microscopic algae floating throughout the pond. Even with proper filtration and regular use of Nature's Defense and Muck Defense beneficial bacteria, some ponds are naturally more predisposed to algae blooms – especially if they get full sun or have a high fish population. If you are constantly battling green or discolored water, then it may be time to add a UV clarifier. To make sure your UV clarifier performs properly, you will need the right pump. Here are some tips for sizing a pump to your unit.

Knowing Which One is Right

When sizing a pump for a UV clarifier, you want the flow rate to be just right. A UV clarifier works by destroying the algae that pass through the unit. Water moving too fast means that the cell wall is not exposed to the UV light long enough to do damage. Move the water too slow and it becomes a sterilizer, killing everything – including your beneficial bacteria. Each manufacturer has different recommendations for their unit, so the best bet is to choose a pump that is close to, but not greater than, the maximum flow rate. Keep in mind, if you have a large pump to power a waterfall or other feature, you may need a separate pump for your UV Clarifier.


UV clarifiers can be run inline or as part of your filter system. Which type you choose will depend on your preference and pond's set up.

  • The Pond Guy UltraUV: Designed for ponds up to 5,000 gallons and pumps up to 2,650 GPH. The EPA Registered UV Light, UltraUV sits outside your pond and can easily be added inline to existing plumbing. This planktonic algae and green water UVC treatment eliminates green water for good and includes step-down barbed fittings to work with 1", 1.25", and 1.5" Flexible Kink Free Tubing.

  • TetraPond GreenFree: The GreenFree UV Clarifier is intended to be used inline and outside your pond. With four sizes to choose from, you are sure to find the right fit, especially if your pond is large. These units work in ponds up to 8,800 gallons and pumps up to 4,400 GPH.

  • Pondmaster Submersible: This unit is unique because it can be used underwater in ponds up to 6,000 gallons. The Pondmaster Submersible can be used with pumps up to 3,000 GPH and depending on which model is selected, it can be used with Flexible Kink Free or PVC Tubing.

  • Pressurized Filter: The Pond Guy AllClear G2 Pressurized Filter will not only fight discolored water in ponds up to 4,500 gallons, but it also provides mechanical and biological filtration. These units sit outside the pond and can be used with pumps up to 2,600 GPH.

Eliminate the Guesswork

If your existing pump is not the right fit and you need to shop for a new pump too, consider getting a combo kit with an UltraUV or AllClear G2. These kits include SolidFlo Solid Handling Pump that is correctly sized for your unit. When purchasing these together in a kit, you will save 10% and be guaranteed clear water!