GreenFree UV Clarifiers

5-Watt GreenFree UV Clarifiers
  • 5-Watt GreenFree UV Clarifiers
  • Tetra Pond 9-watt UV clarifier
  • 18-Watt GreenFree UV Clarifiers
  • 36-Watt GreenFree UV Clarifiers
Product No. 19523
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Making how to get rid of pond algae for good possible!

GreenFree UV Clarifiers work to keep your pond clean, clear, and free of green algae. These dependable clarifiers use ultraviolet light to destroy suspended green algae. As algae are pumped into the Clarifier they are exposed to Ultra-Violet light that destroys the reproductive ability of single celled algae. The dead algae is then pumped out of the Clarifier where it clumps and is removed by your tank’s filtration system. Tetra UV Clarifiers can typically remove heavy algae blooms within five days and keep your pond algae-free long term. GreenFree UV Clarifiers are easy to conceal, durable, install in minutes, and feature a 3-year limited warranty. UL listed. 15 foot power cord.

This product comes in the following sizes:
5 Watt for ponds up to 660 Gallons
9 Watt for ponds up to 1800 Gallons
18 Watt for ponds up to 4400 Gallons
36 Watt for ponds up to 8800 Gallons
GreenFree UV Clarifier is rated 3.8 out of 5 by 13.
Rated 3 out of 5 by from Great product I have a 3700 gal koi pond and the uvc36 did a great job keeping it clear of algae. This is so much better than chemicals, epecially for growing plants and not worrying about my pets drinking the pond water. However after just one seasonal year the unit stopped powering up. I changed bulbs, power sources, all to no avail. It seems like the transformer pack just went out... this product comes with a 3 year warranty and I would expect for the price for things to last a bit longer than 1 year. However I understand even mass produced items have their hiccups, so I am currently waiting on a Customer Service supervisor to handle my claim and send a new filter unit. Because their are 2 reasons I bought this filter; The great product, and its warranty. Hoping to hear back soon before my water turns green. If the customer service responds well, I would give 5 stars for a rating.
Date published: 2018-05-09
Rated 5 out of 5 by from Great product This is my third year with the Tetra UV. Once I learned to control the speed of water through the device I can't be more happy. No green water! It is so nice to enjoy clear water, knowing both my fish and I are happier. Tetra products have always given me better service than other brands and customer service has always been great for me.
Date published: 2017-07-20
Rated 5 out of 5 by from Works as promised Had very green water in my small pond. Bought the Greenfree UV and a week later the water is clear.
Date published: 2017-06-10
Rated 4 out of 5 by from UVC-18 Bought a UVC-18 for our 2,839 gallon pond about a month ago. Seems to be working fine; cleared up our water in about three days and wish I had done so a year ago. Nice to be able to see the fish and bottom of pond. Only thing it took a bit of working on our part to find the right hose and connect UV filter into our plumbing for the pond.
Date published: 2017-05-31
Rated 4 out of 5 by from Clear Pond I bought a UV 01K37 or Item #19520 and the end broke - I emailed Tetra and received a new UV last year or summer before. This year we've bought 2 new replacement bulbs for our unit and neather bulb would light up. We just found out the bulb connection part is bad, we exchanged with the old UV unit and bulb is lite. Should the bulb connection end go bad that quickly?
Date published: 2017-05-07
Rated 1 out of 5 by from terrible warranty bought this last year and the insert broke off and emptied my pond and killed my 15 year old fish. I wrote tetra and said I needed my receipt which I didn't have so I spent all that darn money for nothing and lost my fish on top of it. That thick plastic thing that goes into unit that attached to hose to filter broke in half. I had bought at least 3 of these and refuse to buy another one just to have it broken and never able to get it fixed.
Date published: 2017-04-07
Rated 1 out of 5 by from UVC-36 greenfree ultrviolet clarifier not good Just received our second ultraviolet clarifier and found out the changes made from the 2009 model we have been using created some problems that the 800 number people we called for advise at tetra cold not even give a response for a possible solution. The new unit changed the maximum diameter size for intake and exit hoses from 1 5/8" to 1 1/4". Spent 3 hours going to plumbing supply houses, hardware stores and big box stores to try to find a way to adapt our 1/5/8" hoses we have on our pond to the 1 1/4" maximum now provided on the newer model. Came home and called the 800 number for advise and they said "things change" and that was it. I would think they would have worked out a solution to prevent having to change out our supply and exit hoses for both our ponds but no only the response "things change". Not an acceptable response for a help line.
Date published: 2016-08-17
Rated 5 out of 5 by from works great We have had our pond since 2002 and this works great except when someone left it out all winter (Bflo NY) and it cracked. So we are replacing it with another UCV 18 and our fish will enjoy another wonderful summer. I do also use the barley bales since our pond does get full sun for a large part of the day. Just wish there was a way to stop the hair algae from growing
Date published: 2016-04-30
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I have a 01B37 UV clairifier. What is the flow rating in gal/hr.?

Asked by: Tim l
The number provided tells us the unit is 3 years old, but does not give us the model. The item number is on the outer housing, but you can also go by the watts, which is on the bulb. The flow rate is always going to be half of your pond's total water volume per hour. BREX
Answered by: BREX
Date published: 2018-08-03

I just bought the 18w pond clarifier & I do not see how to remove quartz sleeve for cleaning when needed? Please advice.

Asked by: Jamie 66
It pulls out, basically. You will want to grasp it with something like one of those rubber jar lid removers, and twist/pull to remove it. BREX
Answered by: BREX
Date published: 2018-07-20

looking for part #19354?

Asked by: Bobls
Here is a site where you can buy the parts separately: BREX
Answered by: BREX
Date published: 2018-07-09

My Tetra UVC 18 ballast has seemed to quit after about one or two years. Where can I get a replacement and for approximately how much.

Asked by: mgardnermi
The ballast is not available separately. However, the unit does have a two year warranty so please contact our Care Team at 1-800-526-0650. BREX
Answered by: BREX
Date published: 2018-07-05

Are there any tricks to getting a Tetrapond 5W UV clarifier apart to clean the quartz sleeve? I can't see how it comes out. Thanks. Harry

Asked by: htb 75
The quartz sleeve just twists/pulls out. There is no trick, it just takes strength and tenacity. BREX
Answered by: BREX
Date published: 2018-06-20

how much?

Asked by: teakwoodron
We do not sell directly. Pricing will depend on your store's markup and the model size you need. BREX
Answered by: BREX
Date published: 2018-06-12

 I have a appropriate 2000-2500 gallon pond. I have a 3600gph pump inside a skimmer. I want to put in one of your UV lights and I'm not sure where to put it and what size to get. 

Asked by: BJ4553
The light would go outside the pond. You would run tubing from the pump's outlet to the UV's inlet then from the UV outlet and back to the pond. Considering your flow rate, we'd recommend the UVC-36. BREX
Answered by: BREX
Date published: 2018-06-04

I'm using a dhp3600 going to a bp2500 filter. I am getting about 1200 gph on the outlet to my waterfall on a 500 gallon pond. Can I install the 9watt uv clarifier on this gph output due to the smaller pond size?

Asked by: luckynut
Actually, the UV has to go before the filter or it will create too much pressure for the filter, so we'd recommend a tee or y inserted before the filter, and another line running to the UV then to the falls. BREX
Answered by: BREX
Date published: 2018-05-22
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GreenFree UV Clarifier Guide


Pond Size

Tubing Adapters Included

Max Flow


Up to 660 gallons

3/4", 1", 1 1/4" ID

330 GPH


Up to 1800 gallons

3/4", 1", 1 1/4" ID

900 GPH


Up to 4400 gallons

3/4", 1", 1 1/4" ID

2200 GPH


Up to 8800 gallons

3/4", 1", 1 1/4" ID

4400 GPH