Best UV Pond Clarifiers 2023 (Top Products Compared)

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Best UV Pond Clarifier 2023 (Updated List)

Pond clarifiers are designed to remove green pond water and destroy the algae that causes it with strong UV light. Here you’ll find useful information to help you choose the right clarifier, as well as our UV Clarifier recommendations currently on both the US and UK market.

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UK Pond Owner? We recommend... UK Pond Owner? We recommend...



Removing Algae with UV Clarifiers (Benefits)

UV clarifier clears algae in pond
Algae blooms occur rapidly in summer, with free-swimming algae being the primary cause of green pond water.

One of the main reasons to invest in a UV pond clarifier is to remove pond algae causing green pond water. The strong UV light emitted will destroy free-swimming pond algae at the cellular level, causing them to break down and clump together. After they have been broken down they’ll be cleared by the pond filter system, or simply settle to the bottom of the pond and eventually decompose.

Since free-swimming algae particles are the main reason your pond water is likely green, a UV pond clarifier should greatly improve the clarity of your ponds water after algae levels have been sufficiently reduced. UV clarifiers are also a very safe method of algae removal for fish, so can be used for both koi and goldfish ponds without problems or damage to the ecosystem.

UV clarifiers are a great way to remove free-swimming algae, but will not be able to remove larger forms of algae, such as string algae. These kinds of algae cannot enter the main chamber of the clarifier so would need to be removed using different methods. Often the best way to deal with an algae bloom is with a combination of solutions, such as using a pond vacuum alongside the UV treatment. If green water is your only concern, a UV clarifier is more than enough for the job. If you want to remove all forms of algae, however, check our full article here which explains different methods to help combat all forms of nuisance algae.

What wattage of UV pond light is best?

best UV water clarifier and water light
The strength of UVC required will depend on your size of pond, fish stocks, and amount of algae present.

UV Pond Clarifiers, whether the UV pond light is a separate unit or combined with a pond filter, all have separate power ratings and strengths. As you can imagine, the stronger the UV output of a UV pond light, the stronger its algae destroying properties.

The output of a UV pond light is universally rated in Watts, indicated in its specifications as its Wattage. A common wattage range for UV pond clarifiers is 8w-11w, per 3,000 gallons (10,000~ litres) of pond water to eradicate green pond water. In this range, green pond water algae will be gradually removed, allowing much clearer pond water.

If you’re also looking to greatly remove disease-based free-swimming bacteria, as well as algae, you can purchase a UV Pond Light of up to 15-30+ Watts in strength per 3,000 gallons (10,000~ litres) of water. A higher wattage is recommended if you wish to maintain low bad bacteria levels as well as remove green water. This will be especially beneficial for a larger fish stocked pond, such as koi ponds.

The 8w-11w range is more common for smaller ponds, and should be sufficient to remove almost all green water whilst also reducing free swimming bacteria in a smaller setting.

Will the UV light kill beneficial bacteria, too?

beneficial bacteria in ponds
The majority of beneficial pond bacteria live within your filter box media.

A UV pond clarifier’s main purpose is to eliminate free swimming algae so it can be easily removed by your pond’s filter system. However, UV light will also kill both bad and good pond bacteria that happens to pass through the light. One of the main reasons some pond owners do not like the idea of using a UV pond light is because they’re worried their ponds bacterial balance will be at risk. Even though it’s true that some free swimming bacteria will be removed by the light, the majority of your pond’s beneficial bacteria are safely housed within your filter box.

Within your ponds filter, inside the biological media, millions of beneficial bacteria are working to break down harmful substances. This bacteria will not be effected by a UV clarifier, even if your UV pond light is within your filter itself. So basically, even if some floating beneficial bacteria are removed, your pond’s filter bacteria population will be stable and continue to provide biological support for your pond.

If you have just purchased a new filter, or have carried out a heavy water change, you can consider turning off your UV light for a few weeks for new bacteria to colonize. If you also have an algae problem that just can’t wait, and to help supplement the process of algae removal and bacteria colonization, you can supplement your pond’s filter with good bacteria. We recommend Evolution Aquas Pure Pond (UK link) bacteria.

UV Filter vs UV Clarifier – Which is the Better?

Some box filters also come with UV, providing both filtration and algae removal.

Modern pond box filters and pressurized pond filters commonly come with a built-in UVC pond light. This provides an easy method of clearing pond algae during the filtration process, saving money and additional setup. There is really no difference in function between a pond filter with UVC and a separate pond UV light unit, and both are a good choice for clearing green pond water.

If you’re still in the process of building your pond and have yet to purchase a filter, a pond filter with added UVC may be the most economical choice. This may also be a good choice if you’re looking to upgrade your old box pond filter in near future. Check out our Pond Filter Buyer’s Guide for a great list of recommended pond filters with UV.

If you’re happy with your current pond filter, or require a separate UV Pond Clarifier for a specific reason, purchasing a separate unit is a no-brainer. There are really no drawbacks apart from having an additional item in your pond loop, and it will remove green pond water just as effectively.

Is there a difference between a UV Clarifier and UV Sterilizer?

A UV pond sterilizer and a UV pond clarifier are very similar in terms of function. Both are highly efficient at removing free swimming algae, but a UV pond sterilizer is usually designed to remove a much larger amount of free-swimming harmful bacteria, too. Water flows slower through a UV sterilizer in comparison to a UV clarifier, so more particles and bacteria are destroyed in the process. UV sterilizers work the same as UV clarifiers, but by removing more bacteria along with algae, they have become popular for heavily stocked fish ponds. For example, a koi pond owner may choose a UV sterilizer over a regular pond clarifier to remove more disease causing bacteria which can cause issues with their fish stock.

Both types of UV treatment are fine for algae removal, and the terms are sometimes used interchangeably by manufacturers (which can be confusing). What’s more important is the UV strength of the bulb and making sure the unit supports your pond size and pump strength.  For example, if you have major algae problems or want to remove more harmful bacteria, you can simply select a stronger UV wattage which should provide better results compared to a weaker bulb.

Getting the most from your UV Clarifier (Top Tips)

pond fountain clarifier and aerator
Providing aeration and oxygen is important during algae treatment as bacteria consume oxygen to break down the dead algae particles.

All UV clarifiers will work by passing water through a chamber with UV light, and the water needs time to pass through for successful algae removal. If your current pump is too strong it can damage the clarifier, and if it’s too weak it may not be a sufficient flow rate for algae to be removed. However, it is better to have a weaker pump than a stronger pump, as a pump which is too strong can damage the device due to the pressure build up.

For the easiest UV treatment, we would recommend simply purchasing another pump and connecting it to just the clarifier and nothing else. The benefit of this is that you can more easily control the UV treatment and make sure the pump is the perfect strength for the clarifier for maximum algae removal. It is also always good to have a backup pump for emergencies, so having a separate one is a nice safeguard in case of problems. For a list of great pump choices, see our detailed guide on this here.

As well as having a separate pump, making sure to provide plenty of aeration to waters during treatment is important to maintain healthy oxygen content for fish. Extra aeration and oxygen can be provided with a dedicated air pump or even a waterfall of fountain display. Cleaning the bottom sludge of any dead algae should also be a carried out before and after treatment to ensure water quality remains stable.

Best UV Pond Clarifier Reviews 2023

Due to the different brands available between the US and UK markets, we’ve researched and divided our categories to provide both American and UK pond owners a review on the best UV pond clarifiers available. We have listed below our UV clarifier picks available to both the US and UK market.

US - Best UV Clarifiers US - Best UV Clarifiers

Our Top Pick

1) TetraPond GreenFree UV Clarifier

TetraPond GreenFree UV Clarifier heavy duty water clarifier

The TetraPond GreenFree UV pond clarifier is a heavy duty series of UV pond lights which provide complete algae removal within 5 days of operation. This clarifier series provides UV strengths for ponds of various sizes, from 660 gallons to 8800 gallons. The models designed for the smallest ponds are powered by 5W UV lights and the largest by 36W UV lights. The UV light will last for 11 months of continuous operation, and is recommended to be replaced at least every 2 seasons for maximum efficiency.

No tubing is included for the inlet/outlet valves so you’ll need to have that on hand. 3/4 or 1 inch tubing is recommended, as well as clamps to secure in place. Since the inlet/outlet valves are on opposite sides of this UV clarifier, make sure to take that into account when planning your plumbing design. The clarifier is also not submersible and needs to be kept above the water, so don’t get it wet!

Overall, a very solid UV pond light which should eliminate all free swimming pond algae with a great 3 year warranty in case of problems. Just make sure you select the correct UV strength for your pond size for the most effective algae removal.

  • Pond Sizes: 660, 1800, 4400, 8800 gallons.
  • UV Strength: 5W, 9W, 18W, 36W
  • UV Bulb Usage: 11 months constant operation
  • Submersible: No
  • Adapters: 3/4 or 1 inch ID Tubing
  • Warranty: 3 Year Limited
  • Replacement Bulb: TetraPond UV Clarifier Blub

Best For Small Ponds

2) Jebao Stainless Steel UVC Clarifier,

An extremely powerful UV clarifier option from Jebao, designed for ponds with constant algae problems and highly stocked fish ponds, up to 8000 gallons.

This clarifier unit is rated at a whopping 55w, which makes it the strongest clarifier blub on offer here. The external casing is made from highly polished reflective stainless steel, which helps provide up to 35% additional UV efficiency compared to plastic casings. Due to the fact the blub is rated almost twice as high as other units, and it runs much hotter, maintaining high efficiency is important for longevity. From personal experience with using a range of UV clarifiers, higher watt parts due tend to burn out faster and need replacements, so maybe Jebao is on to something here?

As with most clarifiers, no additional tubing or pump is included so you’ll need to make sure you have these ready before you can install within your pond. When installing, be aware that the UV bulb needs to be firmly secured in the fitting and the top screwed on tightly for the clarifier to work!

The clarifier claims to accept an Inlet & outlet adapter ID of 0.75″, 1″, 1.25″, 1.5″, however, during testing we found that larger sizes were needed – 1″, 1.5″, and 2″ ID Tubing. Although this could be differences in models (i.e., a newer model which hasn’t had an updated spec sheet), be aware that if your adapters do not fit the specified sizes, try a size up!

In conclusion, the Jebao 55w Stainless Steel Clarifier is a good choice for lager ponds or ponds struggling with algae. The wattage may be overkill for smaller ponds, or those looking for a cheaper-to-run unit, but with its 35% improved efficiency steel casing design, you really can’t get much better in this wattage range.

  • Pond Sizes: up to 8000 Gallons
  • UV Strength: 55W
  • Submersible: No
  • Adapters: 1″, 1.5″, and 2″ ID Tubing
  • Warranty: 3 Year Limited
  • Replacement Bulb: Jebao UV Clarifier Bulb

Best For Koi Ponds

3) OASE Vitronic UV Pond Clarifier

water clarifier for fish ponds

A great UV clarifier for koi ponds due to its powerful 36w UV light, which can eliminate algae in ponds up to 10,000 gallons. It supports a higher volume of water clarification compared to some higher rated parts due to a higher flow-through rate and efficient design. The OASE Vitronic series of pond clarifiers are designed for fish ponds and made to easily integrate into your existing pond system, such as into an Oase filter. They support a wide range of hose sizes, and have clear intake adapter connections which show the clairfier is working and drawing water.

Although suitable for clearing green water in ponds up to 10,000 gallons, a pump of around 2,000 GPH is recommended for the best algae removal and to prevent damage to the clarifier.  Water flows particularly slow in this model, so it would be a good choice for koi pond owners looking to remove a large chunk of harmful bacteria alongside the free-swimming algae.

The inlet and outlet are on opposite sides of the clarifier, which may make plumbing a little more awkward in some situations, but this is not a deal breaker. The UV light is housed securely and the clarifier features a handy quick release function for easy bulb replacement when needed.

The unit is not submersible, so would need to be installed outside your pond water, and would be a great choice for heavy stocked koi or goldfish ponds.

  • Pond Sizes: 5000 – 10,000 Gallons
  • UV Strength: 36w
  • UV Bulb Usage: 12 months constant operation
  • Submersible: No
  • Adapters: 1″, 1 1/4″, 1 1/2″ ID Tubing
  • Warranty: 3 Year Limited
  • Replacement Bulb: OASE UV Clarifier Bulb

UK - Best UV Clarifiers UK - Best UV Clarifiers

Our Top Pick

1) AllPondSolutions UV Pond Clarifier

A UV clarifier series with a huge range of different models, covering both small ponds and large ponds. AllPondSolutions UV Clarifiers are easy to install, flexible, and work to removal algae very quickly. The units come with different adapter options, as well as wall mounting clips and screws if you want to hide the clarifier out of sight. Each model comes with a different strength UV light, but all are guaranteed to work for at least 11 months of constant use.

We really like the flexibility on offer with these UV clarifiers, as they offer 3 different inlet/outlet options so you’re able to run the output to a water feature or filter if required. The clear flow horsetail on the smaller units is also a nice addition so you can see the flow of water as it runs.

Be aware, this clarifier does slow water flow quite considerably due to its spinning helix design which allows water more exposure time inside the unit. You will need to check your pond pump’s strength against the max flow rate to ensure you can run water effectively.

In terms of cleaning, the clarifier does need regular cleaning so it doesn’t become clogged and the bulb needs changing every 2 seasons. The bulb is fairly easy to change but can be quite fiddly.

Overall, a nice UV pond clarifier with a decent amount of options and flexibility. Just be sure your pond pump is up to the job!

  • Pond Sizes: 4000, 7000, 20000, 35000, 45000 liters
  • UV Strength: 9W, 11W, 18W 36W
  • UV Bulb Usage: 11 months constant operation
  • Submersible: No
  • Adapters: 13, 20, 25, 32 and 40mm tubing
  • Warranty: 1 Year Limited
  • Replacement Bulb: AllPondSoltions UV Clarifier Bulb

Best For Small Ponds

2) Blagdon Mini Pond Clarifier

The Blagdon Mini Pond Clarifier is an extremely compact and easy to install UV solution for smaller ponds of up to 4500 litres. The unit comes with a standard 9w UV pond light which is easy to replace and clean when required. The bulb will be able to work constantly for 11 months of the year, and is recommended to be changed every 2 seasons.

Even though this UV clarifier has been designed for smaller ponds, you can connect more than a single unit together via optional wide bore links if you needed more UV strength. This means if you purchased the clarifier and wanted to speed up algae removal, another unit can be connected fairly easily for double the strength.

Blagdon also offer a lengthy 3 year warranty with this clarifier and the replacement bulbs are fairly cheap if needed. A great little UV clarifier for small ponds or preformed ponds with algae problems!

  • Pond Sizes: up to 4500 liters
  • UV Strength: 9W
  • UV Bulb Usage: 11 months constant operation
  • Submersible: No
  • Adapters: 3/4, 1, 1 1/4 inch
  • Warranty: 3 Year Limited
  • Replacement Bulb: Blagdon Mini Pond Clarifier Bulb


3 thoughts on “Best UV Pond Clarifiers 2023 (Top Products Compared)”

  1. The information in this article is great, but my “pond” is only 50 Gallons. Is there a uv clarifier/pond filter combo that would work for me?
    My pond has shrimp, snails and birds and other animals drink out of it so I can’t use those liquid algaecides.


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