Tetra 19520-01 ACC PND GREENFREE 9W UV-CLARI 1C (Open Box)

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!