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TetraPond UVC GreenFree UV Clarifier Series

1. UVC-5 Watt
2. UVC-9 Watt
3. UVC-18 Watt
4. UVC-36 Watt

UV Clarifiers TetraPond
TetraPond’s 4 models



Looking for a solution to those algae blooms in your pond?

The TetraPond GreenFree Ultraviolet Clarifier Series makes it easy for you to have an algae-free pond water even during the hottest times of the year. This line of model is easily recognizable due to its characteristic green color. There are 4 different strengths in this series, meant for different sizes of pond.

These clarifiers are, on top of being easy to install and maintain, also equipped with a long-lasting, durable UV bulb to ensure the most efficient performance. The units also have viewing windows to see when the lamp is on. The lamp itself lasts up to 11 months of continuous use.

By exposing the algae to high levels of ultraviolet light, they die and clump together. Combine this series with a (mechanical or biological) filter to trap and clear out the dead algae.

Usually clears your pond of ugly floating algae within five days, and after that continues to keep it free of algae.


Durable but not submersible

These clarifiers are not submersible, so installation is outside of the pond. As such they come in a durable and weather resistant housing. (But make sure to not position them in a place where there is a likelihood of it sitting in puddles or falling into the pond.)

On top of this, this durability is even more improved by the presence of a stainless steel reflector on the inside of the plastic housing. This increases the UV exposure to the algae, but also prevents the plastic turning brittle over time (plastic is also degraded by UV exposure).

A quartz sleeve around the lamp helps to protect it from debris, such as little stones.

Multi-diameter inlet/outlet hose connectors add to installation convenience.

Every model in this series comes with a 15 foot power cord. Also includes a 3/4″, 1″ and 1 1/4″ ID stepped hose connector.

Tubing not included.


Seasonal Use

In summer, these units should remain in operation 24 hours a day.
And in winter, it is recommended to store the clarifier in a frost-free location.



This TetraPond UVC GreenFree Series, that dates from 2011, is an improvement from the previous model. The manufacturer did a redesign, and added more protection to the power cord interface, as well as the viewing window.


About TetraPond

TetraPond is a US company that was founded way back in 1960. They have been producing pet and pond products ever since. Their main offices are located in Blacksburg, Virginia.


Comes in 4 sizes

The GreenFree Series has 4 sizes, each with a different bulb strength for a different size of pond. There’s 5, 9, 18 and 36 watts:


UVC-5 Watt

tetrapond 5w
TetraPond UVC-5 5 Watt Clarifier

The TetraPond UVC 5 Watt Clarifier is the smallest one of the TetraPond GreenFree UV Clarifier series. It is a small and robust unit, that steadily does what its supposed to do.

Volume of pond served

Designed for ponds up to max 660 gallons.

Combine with a pump with a max flow of 330 gph. Be sure not to use a pump that is too powerful, so the water flow past the bulb isn’t too fast.

Product dimensions: 4.1 x 12 x 8.8 inches

This model is perfect for ponds up to 400 gals in all situations.

If your pond is a little bigger, say somewhere between 400 and 660 gals, then this clarifier does the trick, but only if it is in a condition that does not favor excessive algae growth.


  • if you don’t have lots of fish
  • if your pond is situated in the shadow
  • if you have a plant coverage of 50 to 75%
  • if you regularly clean your filter
  • and if you do not get a lot of heat waves during the summer

… then this uv light will be able to handle the algae load in your pond. This has been backed up by the experience of many other users.

However, I would not recommend this uv light for ponds that are bigger than 400 gallons and that have very favorable conditions for algae (lots of sun, lots of fish, few plants,…). Even though the manufacturer says you can use it in ponds of up to 660 gal, in my experience and from what other people have said this might be a bit too optimistic.

For example: in a heat wave, with the algae multiplying rapidly, this little unit might have a hard time keeping up.

I always recommend being on the safe side and getting somewhat more capacity, because if the one you buy isn’t adequate, then you’ll end up buying the next model up and you will basically pay double the price. There’s no harm in having a stronger unit for your pond, it’ll only work more efficiently.

Conclusion: if your pond is in such a situation, I would recommend the next size up (and stronger model): the Tetrapond UVC-9 9-watt GreenFree UV Clarifier.

See the UVC-5 Watt here on Amazon.com



UVC-9 Watt

TetraPond 9W
TetraPond UVC-9 9 Watt Clarifier

The TetraPond UVC-9 Watt Clarifier is the next size up in this series. Designed to kill the algae in a matter of days. Combine with an appropiate pump to clear out the dead algae.

Volume of pond served

Designed for ponds with a miximum size of 1,800 gal.

Combine with a pump with a max flow of 900 gph. Don’t use a pump with a flow higher than that or performance will decrease.

Product dimensions: 4.1 x 15.2 x 9 inches

See on Amazon.com


UVC-18 Watt

TetraPond UVC-18 18 Watt Clarifier
TetraPond UVC-18 18 Watt Clarifier


Volume of pond served

Designed for ponds up to max 4,400 gal.
Combine with a pump with a max flow of 2,200 gph.

Product dimensions: 4.1 x 15.2 x 9 inches


See on Amazon.com





UVC-36 Watt

TetraPond UVC-36 36 Watt Clarifier
TetraPond UVC-36 36 Watt Clarifier


Volume of pond served

Designed for ponds up to max 8,800 gal.
Combine with a pump with a max flow of 4,400 gph.

Product dimensions: 4.1 x 21.5 x 9.6 inches


See on Amazon.com




Every clarifier in this series comes with its bulb included.

The unit is well built and is sealed against the elements.

With its simple plumbing connections common for pond owners, it is easy to assemble and install. Just follow the clear instructions, and connect the clarifier to the hoses. (Tubes are not included.) The connections are “stepped” and thus adaptable to tubing of many sizes.

Also, this series has a very long power cord (15 ft), which can be very handy.

No need to drain, clean and re-fill your pond! One of the advantages of having a UV light is that you don’t have to do any more water changes. Even though some people still do, for example, a 25% water change in the beginning when they install the UV light in the pond, this is not really needed.

With this series, it is possible that, literally, a few days after plugging your TetraPond model in, the algae will be gone. Fast, like overnight.

Overall, this is a good and long lasting uv unit.



Some people have mentioned some issues they have with this model.

For example, there is the fact that the inlet and outlet ports are on opposite sides, which could -depending on your situation- make the plumbing a little bit more difficult. It also takes up more space than necessary.

Another thing to be aware of is that this clarifier needs to be taken in before freezing weather. It can crack in such conditions.

Probably a valid comment from somebody is this one:

I think the plastic and the fittings should be a little more rugged. If not careful, you could easily break / crack this unit when clamping and tightening.

But otherwise the unit is very well built, sealed against the elements and has a very long power cord.

Some people were disappointed by the fact that no tubing was included. This should go without saying (as this is true all uv lights), but the tubing is not included with these clarifiers. It would be difficult to do so anyway, as every pond has different requirements. You need to buy your own flexible tubing to connect to the inlet and the outlet.


What Do Other People Say?

These are some comments from people who bought this product on Amazon.

Numerous people commented about the efficiency of this unit:

“Cleaned (and has kept clean) a small pond that no matter how many chemicals we dumped into it would turn into an algae breeding ground! This unit is very well built, sealed against the elements and has a very long power cord. Just be sure not to use too powerful a pump so the water flow past the bulb isn’t too fast.”

“The pond has been crystal clear since, right down to the bottom where you can see the pebbles.”

“Our water started to clear up in a few days and within 2 weeks it was crystal clear. Really amazing and I was skeptical. Would recommend if you have algae overgrowth issues. None of the chemicals worked for us. Nowadays, it’s a really cool thing to buy something that actually works – this does.”


Others have talked about the easy of installing:

“Easy to assemble and integrate into my existing filtration system.”

“Was easy to install and is keeping my small pond crystal clear. It was also less expensive at amazon vs the pond store; music to my wallet.”


Click here to read more reviews on Amazon



All the units in this series come with a 3 year warranty, so in case you need to swap or return your clarifier, you can safely do so.


Practical and necessary, this is a necessary tool in the fight against pond alge. Easy assembly, plug it in and – depending on your situation – a few days later your pond might be algae-free.

And remember, if you’re looking for a clarifier, you can’t go wrong by buying a larger unit than the size of your pond asks for according to the manufacturer. If you do that you’ll just end up with more effective algae control and even bacterial disinfection. When in doubt, ALWAYS go for the stronger model.


Click here to see the current price on Amazon.com


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