This article is a review of the TetraPond UVC-5 GreenFree Ultraviolet Clarifier.
For most of the 30 years I have had my 90 gallon, kidney shaped pond, I have left it “natural”. That is, no filter or pumps. I have always run an air pump with air stone to provide extra agitation and oxygenation to the water and to leave an air hole through the ice in winter. At one point I had a small internal pond filter powered by a small pump, but after a couple of years I stopped using it. It was a bit cumbersome to maintain and didn’t seem to do much anyway. At other times I tried a small fountain (water coming out of a turtles mouth) and also tried a plastic waterfall, but stopped using that because the sound to the water movement bothered me.
I recently got psyched on the idea of an external pond filter and built a DIY filter from a plastic container onto which I plumbed 2 bulkhead fittings. Water moves from below, through the filter media, and out the top. Initially I used bio-balls and lava rock, but I later replaced the lava rock with matala. Even after adding a layer of white polyester filter medium to the filter, I was still left with dark pea soup water. If my fish were more than 2 inches below the surface they couldn’t be seen. In fact, I would sometimes go months between fish sightings, wandering if I still had live fish in the pond.
I reviewed articles on the internet and on YouTube regarding algae management. Because I was growing plants in the pond I didn’t want to use a herbicide if I could avoid it. For years I had seen these ultraviolet filters in the stores, but never quite understood why someone would really need one. As I finally understood that the peas in my pea soup were actually suspended unicellular algae which were too small to be filtered effectively with mechanical media, and that I was struggling to achieve an ecological balance that would allow the plants but not the algae to thrive, I thought I’d give the UV sterilizer a try.
The unit is pretty straightforward in design. Water enters a plastic tube containing the light bulb and is exposed to the ultraviolet light as it passes the bulb. The algae is sterilized in the sense it can no longer reproduce. It eventually dies. The dead algae clumps together forming a mass large enough to be filtered by the mechanical filter(s).
Since my pond is only 90 gallons, I bought the smallest unit, UVC-5, 5 indicating it uses a 5 watt bulb. You have to replace the bulbs every year because they lose their effectiveness over time. The electricity is minimal, but the bulb will cost $14 for each replacement. So figure about $20 per year running costs.
Connecting the unit required me to buy 2 adapters to go from 3/4 inch (the smallest diameter on the unit) to my 1/2 inch hose size. So the pump immersed in the pond connects to the clarifier and then the clarifier connects to the external pond filter. The external pond filter returns the water to the pond.
After about 5 days continuous use, I didn’t see any change. At that point, to accelerate to process of the initial cleanup, I did a couple of water changes to flush out the bulk of the algae from the pond, hoping that the uvc-5 would maintain it.
It is now about 3 weeks from the water change, and the water is clearer yet, if that is possible. It looks so clear that at least by appearance, you would almost feel comfortable dipping a cup in the water and drinking it. So, instead of the algae returning, the pond clarity has been maintained/improved. You can easily see all the way to the bottom with even minimal light outside.
Now, you might say that I cleaned up the nutrients in the pond by doing the water changes. However, my tap water has a lot of nitrate and some phosphate in it plus I add plant fertilizer to the pond weekly (Thrive) which contains both macro and micro plant nutrients. So, if the algae were going to bloom again, they have nutrients available.
So, as far as I am concerned, problem solved.
Check out my post on the Green Killing Machine UV sterilizer for aquariums.
0 Comments