TETRA GreenFree Ultraviolet Pond Clarifier, 18-watt - Chewy.com

Tetra GreenFree Ultraviolet Pond Clarifier

By Tetra
Rated 4.6923 out of 5 stars

Spend $100, Get $30 eGift Card With Code: WINTER

Must enter code at checkout to redeem
$247.78Chewy Price
$294.99Chewy Price

In Stock
FREE 1-3 day shipping

Frequently Bought Together

This Item - Tetra GreenFree Ultraviolet Pond Clarifier, 18-watt
Rated 4.6923 out of 5 stars
$247.78Chewy Price

Spend $100, Get $30 eGift Card

Tetra Pond 5 Watt UV Replacement Bulb, 36-watt
Rated 3.6667 out of 5 stars
$22.76Chewy Price
Tetra Pond Tubing, Corrugated, 1.25-in x 20-ft
Rated 3 out of 5 stars
$20.99Chewy Price

Spend $100, Get $30 eGift Card

Total Price: $0.00

About This Item


  • Helps combat heavy algae blooms in ponds and water gardens for a clean, green-free finish.
  • Comes with a UV bulb that can last for up to 11 months.
  • The included stainless-steel insert helps increase UV exposure.
  • Designed for ponds that can hold up to 1,800 gallons.
  • Can help remove full bloom in up to 8 days.

See More

Compare Similar Items

Customer Rating
Rated 4.6923 out of 5 stars
Rated 3.75 out of 5 stars
$247.78Chewy Price
$362.04Chewy Price
$173.45Chewy Price
Fish TypeKoi & Pond FishKoi & Pond FishKoi & Pond Fish
Aquarium TypePondPondPond

Questions & Answers

7 Customer Questions

Can this be used for 200 gallon ponds, or is it too powerful?
Answer by ChewyApr 27, 2019
The 5 Watt clarifier is for ponds up to 660 gallons, the 9 Watt is for ponds up to 1800 gallons, the 18 Watt is for ponds up to 4400 gallons, and the 36 Watt is for ponds up to 8800 gallons.

Do you sell replacement parts for the Tetra 36w UV clarifier? I need a new quartz sleeve. Thanks!
Answer by ChewyMay 12, 2019
While we do currently carry the Tetra Pond UV Replacement Bulb for this pond clarifier, we do not carry other replacement parts. Replacement parts may be found through the manufacturer.

Neither one of us can tell if the UV light is on through the window. How will we be able to even tell if it is burned out? Night or day, no light.
Answer by ChewyMay 10, 2021
If the unit is fully installed, endcap screwed on tight, and the light window does not appear to be a lavender color in pitch darkness, then yes, you may have an issue. If that is the case, try a different outlet of course, check to make sure the bulb is staying connected and not loose. If there are no improvements, then please contact customer service.

How do you install the Tetra GreenFree Ultraviolet Pond Clarifier?
Answer by ChewyApr 10, 2020
Installation instructions come with the unit. You need a submersible pump inside the pond, and tubing that attaches to the pump to the UV inlet. Additional tubing will also attach to the outlet and return back to the pond. Install a submersible pump that will move half of your pond water through this UV every hour. We recommend installing it between the pump and the filter system, so the filter catches the dead and dying algae. It sits outside the pond, of course, and could be operated by itself with a separate pump.

ReviewsWrite a Review

Rated 4.6923 out of 5 stars
13 Reviews
Would recommend to a friend

13 Customer Reviews

Filter by reviews that mention

Rated 1 out of 5 stars
By ELW1 on Sep 21, 2022

Yuk Yuk Yuk

A month after receiving and installing, the bulb quit working. Replaced the bulb yesterday and it is already out this morning.

Rated 5 out of 5 stars
By UVClarifier on Jun 22, 2022

It Works well

The device installed easily into our system, but when we started it up, the light didn't work. After some back and forth discussion of the problem with customer service, while our pond got more and more cloudy, Chewy sent another UV bulb. We installed that and now it is working well!! Our pond water is beautifully clear.

Rated 5 out of 5 stars
By ASWNY on May 23, 2022

If I could give it 10 stars I would!

We're completely blown away by how well this device worked. After the winter the algae had bloomed and we tried other things to get rid of it, which didn't work. Our pond looked like dark pea soup. You could not see anything. After 3 days with the UV light we saw a noticeable improvement and after 5 days the pond is crystal clear. Don't waste your money on anything else, get this!

Rated 5 out of 5 stars
By MomAlmighty on Aug 31, 2021

Amazing results!

I had a little 125 gallon pond installed for my Red-eared Sliders last spring and released them into it on July 4th. The summer heat and sun turned the water green and icky despite covering the area with a pergola and multiple turtle safe treatment options. I finally emailed one of the product companies asking "what do I do about this algae?" I got a response, and after they looked at pictures and asked some questions, recommended a UV filter like this one. After doing a little research and reading lots of customer reviews I ordered this from Chewy. One day in saw incredible improvement. In three days the water was crystal clear! It's amazing how quickly and efficiently this solved a really troublesome problem. I wish I'd known about this UV filter a lot sooner!

Rated 5 out of 5 stars
By Pondify on Nov 1, 2021

Glowing Accolades!

I have a pond that has always had an algae and clarity problem. I added this little bigger to the pump line and 2 days later I cleaned a lot of dead algae from the pump filter. Amazing job!!

Rated 5 out of 5 stars
By Mikesculle on Oct 19, 2021

Wow the uv light filter did just what it promised

I received my uv light filter 10 17 21 and my ponds have never been clearer if you're thinking of purchasing one I highly recommend it

Rated 5 out of 5 stars
By Doug on Jul 10, 2021


Set this up...and the water went from pea green soup to clear as can be in 8 days. I was skeptical, but now true believer.

Rated 5 out of 5 stars
By Fishhead2 on Dec 11, 2020

Great stuff. Super annoying

Your stuff is always great, thats why I shop here. Just wish you'd stop flippin emailing me.

Rated 5 out of 5 stars
By Teresa on Aug 26, 2020

It works!!!

I could barely see my goldfish in my outside 600 gal pond. The water and rocks had so much green algae. After installing the UV light and waiting 1 week it was amazingly clear. I could not believe it! Great price. Easy install too. Definitely recommend.

Rated 5 out of 5 stars
By riosmom on Jun 27, 2020

I can see clearly now

We purchased a new home last year with a small pond and we are still learning the ins and outs of everything. Our UV filter froze and broke over the winter which led us to having the worst algae problem once spring began. (lesson learned) We tried everything- algaefix, giving some fish away, pond vac, muck remover, barley straw, etc until we realized our old UV filter broke. We could barely see 1" into the water it was so thick and green. We ordered this immediately and within a day the water started looking clear again. It's a week since we installed it now and we can see to the bottom of the pond again! Our fish are so happy and we can actually see them now. I would definitely recommend this.