Tetra Pond GreenFree 9W UV Clarifier

I built a koy pond in my garden 3 years ago. 4 cubic meters or so. I've had all the normal issues about a pond, mainly the massive growing of microscopic algae that turns the water opaque green. This always dissapointed me because it was not possible to see the fish. After two weeks from a deep cleaning I couldn't even know if they were alive. After doing some research in the internet I took ideas from different designs and decided to built my own filter. It's an external tank-type filter. The water is pumped from the pond, goes through the TetraPond UVC-9 lamp, then goes to the bottom of the tank (there is a circular flow which produces a cyclonic effect on the solid debries). Some bio-balls help with the first biologic processing of the organic solids. Then the water passes upwards thru four layers of Matala Mats (black, green, blue and gray), combined with a last group of bio-balls at the top of the tank. At the top of the tank the water falls thru a side sink directly to the pond. It's a very simple design, and I am happy to say that IT REALLY WORKS!!!! This system kills the microscopic algae, filters almost all the solid debries, treats biologically and chemically the water and makes a very efficient processing of the solids. I started the field test with the pond totally opaque green, since I needed to prove the efficiency of the system. The combination of these different elements was able to totally clear the water in only 9 days!! By now it's been more than 3 months since the last time the microscopic algae showed in my pond. My fish are healthy and are growing noticeablely, I am sure they never lived in a better quality water. The maintenance couln't be easier: I just have to turn the pump off, dismount the Matala layers and rinse everything with a regular hose. The tank also is rinsed and the waste water is disposed of thru a control valve mounted at the bottom of the tank. Finally I reassemble the parts and the system is ready to work again. The Matala mats came in 39"x24" sheets, so I still have spare material for two more filters, If I decided to build more ponds for my friends. I strongly recommend Matala Mats, TetraPond UVC-9 UV lamps and the bio balls to any pond enthusiast.

Works well! Seems a little pricey, but does a fantastic job keeping our pond clear and clean . It was easy to install.

Thanks to 2020 being so, well 2020, we had a lot of lock-down time on our hands. We got a ton of projects around the house done, including building a couple of ponds with a little mini-stream connecting them. We live in Miami, so naturally everything was happy for the first 6 or so weeks, then came the Algae explosion. We could no longer even see our wonderful koi, comets and African Ciclids. Only the guppies and mollies hanging out at the surface were evident. We added the 1800 gallon model for our 800 gallon pond setup and within three days we were able to see all our fish again and within a week the water was as clear as the day we filled the pond. It just works and was easy for me to install - I just cut off the smaller hose diameter "step downs" on the intake and outlet nipples since we're using 1.25" tubing. Don't touch the bulb with your oily hands when you set it up and you should be able to avoid the symptom other reviewers have posted around very short bulb life. We've only had the UV light in for 6 weeks, so I can't speak to long term UV bulb life, but it's definitely doing it's job and I'll be happy even if I have to replace the bulb 2 or even 4 times per year. The power consumption is minimal, but I'm considering the pros/cons of putting the light on a timer and running it 8-12 hours/day vs. 24/7, I just haven't gotten around to it. Hope this review helps anyone staring at pea soup instead of their fish!

I have had a backyard Koi and goldfish pond for about 15 or more years. However, it was SO hard to keep the algae out because after I would clean the pond and dose the water with fish friendly chemical.... they said, either the fish would die or it would green up again too quickly. Here in Nebraska I have always kept a frame over the pond in winter, covered with clear, heavy plastic, and in addition, I would put a heater that only kept the water from freezing. After about the third time my fish died, I gave up on the fish and just ran the waterfall in the pond where I could use enough chemical that it remained clear. Three years ago I decided to give fish a try again, and found that they mostly lived in green water and finally got sick of it. I have tried several "natural" pond cleaners such as the barley grass, of which had zero affect that I could see. A friend told me they use lava rock in their upper chamber and that helps.... did zero for my pond! It was only later that she said "Oh, we also use a UV light unit"!! -- Well crud.... that is probably what keeps her pond looking good!? (I am hoping.) Reading these reviews for this product, I am hopeful that this will end my problem. Many people said that a person needs to slowly add fish to new water so it won't shock them, but I have never had an issue. The best way I have found to clean my pond is to move the hose going to the waterfall, so that it runs away from the pond and at the same time use a garden hose to fill it! The pump pulls green water from the bottom out, while the hose puts fresh water in the top. I live on a ranch so have no city water to deal with and plenty of drainage as we live in the sandhills. It takes about 4 hours and the pond looks really fresh. Just an idea for those of you living in the country. I will review this again at the end of summer 2024, and give my summer end review.

This is an excellent product! It has taken some time, but my pond is becoming more clear every day. The waterfall is flowing better, too, as the whole system is being cleansed. This, along with a gravity fed filter, are the two best investments I've made for the pond. Algae has been a problem every year. Finally, an easier, chemical free solution! The only issue I had was due to my lack of knowledge about "o rings". At first had some leaking, but with the help of my neighbor's channel locks, got it tight and works perfectly now. Thank you for an awesome product!

Been operating a Koi pond for 6 yrs. now. Have learned something every year. This year I experienced the worse "Pea Soup" (smallest of Algae). Large koi not even visible until reaching very surface. I have used this Clarifier in the past. I mistakenly submerged it. DON'T EVER DO THAT!!! Old unit flooded and no longer of use. I let it go too long and pond water became REALLY bad. So, bought another one of these and this time am keeping it OUT of the pond. My pond is approx. 1500.gals. It took about 10 days to notice a good difference. It took another 10 days,(continuous operation), to completely clear the water to the bottom(2-3 ft.). I run the lamp for several hours in am and then pm. Once water clears completely don't need to run continuous. This is the ONLY non chemical way to clear up your water. It also happens to be the BEST way as well. To all of you Novices, NEVER dump out your pond because the water is green (pea soup). You will kill your fish with the sudden change of new,fresh water. I have 6 large Koi,and another 25 gold fish that survived for more that 2 mo. in a very clouded,green,"pea soup" condition. The key is Oxygenation!!! Have enough of that and Fish will probably survive. Best to not leave water like that,of course. I would seriously recommend this product. I like the fact that this model has a viewing window for lamp light so you can always see if its lighting up inside. Keep in mind that the Bulb will perform well for approx. one season unless you have on a timer as I do. I might get 2 yrs.out of it, we'll see. UPDATE; 7/16/21. So, this past spring I had to replace my Main filter. LAGUNA, which operated well for 7yrs. Now, I have same size Laguna, but, it has a 32 watt U/V Lamp,built-in. So I unplugged this Tetra and used only the new 32 watt. Pond couldn't get clear. Re cleaning filter and waiting a week and still can't see bottom of pond. After some thought, I decided to unplug new U/V and go back to this Tetra 9watt. So 1 week of constant on and Pond clear again to bottom (3ft). I believe my 500GPH Pump is moving water TOO FAST past 32watt lamp. ( algae survive). I have a much smaller pump pushing through Tetra, so algae have time, to die. Oh, turns out I miscalculated capacity of pond yrs ago, It's more like 900 gallons. Oops. UPDATE; 7/23/21- Been running this 9watt Tetra in constant-On for more than a week now. Pond remains very clear to bottom. (3ft). Also, Switched my timer on main filter,( 500gpm pump), to be on for 2 hours / 24 hrs. Pond still clear. Don't be afraid to play around and try different things. Just NEVER change out all of the Water!

I have a 13x7x4 koi pond with a decorative waterfall flowing from under the deck. I tried using chemicals and the bright nuclear green color turned a little darker but rapidly recovered. The only effect it had was making the fish seem sickly. After connecting this filter inline just after the pump in kinda a Frankenstein piping mess, I got it working. The first few days the fish were not happy and seemed to be trying to get air from the top of the water. But then everything settled out and the fish started acting normal and the green slowly turned to to kinda a murkey brown, and then began to clear. By day 8 you could see the bottom of the pond. Then by day 10, blackish/brown silt started settling on the stones at the water edge. So I pumped out some water and added water and kept filtering. Now... I can see the bottom of the pond clearly and the fish are energetic and eating like they did before the green stuff appeared.

So I'm giving it a 3 because although I love the design and strudyness of this UV clarifier, I bought this to replace the same one which had gone bad. Unfortunately it lasted only 3 years and the light would no longer work. I hope it last longer this time.

The lamp indicator showing they the Uv light is working did not light up even water is flowing in properly into the inlet of the device and water flowing out of the outlet of the device. And when I open up to take a look at the UV lights, I found the broken pieces inside the tube :((

We used it on our small garden pond, the unit arrived the next day and showed some results in 24hrs. Each day the pond cleared up more, after a week the pond looks great. Easy to set up and install

The first version worked well for 8 years - with a couple of bulb replacements. Excellent for controlling algae.

El producto funciona de maravilla. La primer foto es de 2 días despues de haber limpiado la tortuguera. Como es una tortuguera exterior y le da mucho la luz, no demoraba mucho para ponerse el agua y cristales verdes por las algas. La segunda foto es al 2 o 3 día que le puse el tetrapond green free UV. Y no se ha vuelto a llenar de algas, por lo que recomiendo el producto ampliamente.

It seems to be doing its job