Pondmaster 02940 40 Watt Submersible UV Clarifier

I have a 5000 gallon pond with 18 fish (mostly koi) and about 50% plant coverage. It is in full sun all day in southern California. Without plants the visibility was only 6 inches. With plants and bio filter and so on I still could not get the visibility beyond 18 inches. I had tried chemical algae killers but with all the sun we get and the warm water they can't clear the pond and also the algae comes right back in a week or so. Also I did not want to become dependent on expensive chemicals (nor kill my fish!). When I installed the Pondmaster UV light I noticed small improvements in visibility within 24 hours. Within a week I could see down about 3 feet. It took just a bit over two weeks until I could see the bottom (at 5 feet). Since that time the clarity has improved further so I cannot only see the bottom but I can see it very clearly.

It cleaned up the pond and maintains it well. The only problem that I have with the design is that the socket gets corroded if you don't clean it before winter and keek it clear

So far, so good. I have not seen the bottom of my little pond for two years. After cleaning the pond and putting this light in, the pond has been clear. I hope this continues throughout the summer.

I was skeptical of all the UV hype but after two months of trying every natural method I could find I took the plunge into UV.This Pondmaster 2940 40 watt model seemed to have a good rating from users and more important it looked like it would physically fit where I needed it to go.My pond is not huge, but is in direct sunlight for most of the day. I've added numerous plants to help control the amount of sunlight getting in and the water continued to get greener.The pond is about 1200 gal. it's 2.5 ft deep at the deepest, about 18 feet by 4 feet, several shelves for shallow plants and a small extra shallow bog area. The filtration and pumping is handled with a 3 inch bottom drain feeding a 32 gal settling tank that is plumbed directly to the Sequence 4500 external pump. There is also a small pool type skimmer keeping the surface water clean that feeds into the pump line directly. That pump sends the water up the small incline to a 32 gal bottom feed Skippy style bio-filter full of mixed poly media. The water free flows out of the tank into a small rock filled creek to aid in aeration of the water. BTW the pump is restricted to a much lower flow than maximum rating.I was able to place the Pondmater 2940 in the settling tank and connect it directly to the outlet of the tank going into the Sequence pump. This was one of the most highly recommended places to put the UV so all that dead algae would be sent directly to the filter. The UV was positioned vertically and the ballast is above the normal high water line in the tank. My water was so green that the first glow ring on the UV was not visible in the tank and it is only about 3 inches in the water.After 2 days of UV treatment, my green water pond became the oddest gray water zombie death pond I have ever seen. It was the color of death. Algae death! There was so much dead algae I put a simple flow through trap in the stream bed to try and get all the flow thru from the filter. there was no way the biobugs were eating all this.I did a partial 15% water change on day 3 and another on on day 5. I also agitated the bio filter and pushed the gunk water out of the pond and watered the lawn with it. :-) On day 5 the gray vanished, the water was clear(er) but the bottom was still hazy. The clearing continued at an amazing pace and on day 8 my pond was completely and totally free of free floating algae and crystal clear. UV clarifier/sterilizer really work. I'm a convert. I'll never build a pond again without planning the UV into the process.Your results may vary from mine. I know this 40 watt UV unit is over sized for my pond capacity. Everything on this pond is over-sized. I can't comment on how durable the unit is except to say the construction is good. The fittings are solid and the isolation of the UV light seems good. Obviously the flow and dwell time in my setup is good. The pond has stayed crystal clear now for over a week and we just went through the summer solstice so the sunlight in my back yard is as strong as it gets right now.The unit is solid, easy to install, plenty of power for larger installations and it works!

great uv output. cool light that lets you know its on. this is large uv unit and works well for my 3000 gallon pond

We finally decided to spend the $ to get a UV light and so glad that we did. Within 7 to 10 days with it running 24/7 our pond was completely clear! It is incredible, we can even see the fish swimming through the roots of our pond plants. This is a great product and love the feature of the external lights on the device, that let you know that it is working. Fish are so healthy and happy that they can see each other! Lol