What is a UV Clarifier?
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UV Sterilizers and Clarifiers are tools designed to clear murky green pond water. In most cases, green water is caused by an abundance of single-celled algae suspended in the water. Green water is also known as “algae bloom” and often occurs when a pond has high levels of both plant nutrients and sunlight. UV sterilizers and clarifiers work by using ultraviolet light to kill the single-celled algae that cause green water. It’s important to note that UV light only kills single-celled algae and won’t kill string algae or other forms of complex algae in a pond. There are other treatments for string algae (also called blanket weed or hair algae), such as barley straw treatments.
What’s the Difference Between a Sterilizer and a Clarifier?
The main difference between a sterilizer and a clarifier is the strength of the UV light compared to the amount of water in a pond. For example, a 40-watt UV light could act as a “sterilizer” in a pond that’s around 1,400 gallons, since the volume is quite small. If we use the same UV unit in a 4,000-gallon pond, it would be classified as a “clarifier.” When used as a sterilizer, the UV unit is likely to eliminate green water entirely, no matter what type of pond it is. In addition, the sterilizer will likely kill some bad bacteria and parasites in the water. A clarifier, on the other hand, is said to “control” green water. If you are using a clarifier, it’s recommended that the pond have a good amount of plant coverage and partial shade to help cut down on algae growth.
For most ponds, using the UV unit in “clarifier” mode (10 Watts of UV per 1000 gallons) should be sufficient to clear up green water. Even in a healthy pond, a UV clarifier can help kick things up a notch to give the water a “polished” look. However, if you live in an area that is very hot and sunny with not much shade and you have an obvious green water problem, you may want to bump that up closer to sterilizer numbers—30 Watts per 1000 gallons.
The ideal place to install a UV clarifier is after the biological filtration. This way there’s no chance of any debris damaging the quartz tube inside the unit. However, if you’re using a waterfall filter, it’s not possible to install the UV after the biological filtration since the waterfall is the last step in the process. In this case, the only option is to install the UV before the waterfall filter. If doing this, make sure you have a quality skimmer installed that will filter out any larger debris before it hits the UV.
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UV Lights Built into a Pressurized Biological Filter
Some pressurized biological filters on the market have built in UV lights which provides an “all-in-one” filter with biological filtration and UV Clarification. The UV lights in these all- in-one units will likely be fine when used as a clarifier. If you need additional UV sterilization, you can always add a stand-alone UV clarifier/sterilizer after the biological filter, before the water is returned to the pond.
For more information visit our UV Clarifier page!
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