How Does a UV Pond Filter Work?

Updated March 23, 2017

Crystal clear water in a pond can seem like an unobtainable outcome. It is important to note that cloudy pond water is often the result of free-floating algae populations. Ultraviolet (UV) filters eliminate these organisms, resulting in less murky pond water.

Effect of UV Radiation

Ultraviolet radiation causes irreparable damage to the cellular structure of microorganisms such as algae and bacteria. It does this by mutating the DNA housed within the cell's nucleus. As algae encounter UV light, they clump together, which aids in their removal by other mechanical filtration methods. UV radiation can help to eradicate free-floating algae in a pond and stop the proliferation of algal blooms.

Method of Action

A UV filter, also referred to as a clarifier or sterilizer, contains a bulb that emits both ultraviolet and visible light. This bulb is usually located in a waterproof section of the filter. The filter hooks up to a pump that pulls water from the pond and through the filter at a specific flow rate.


An ultraviolet filter is highly effective at killing free-floating algae and bacteria, but provides no assistance in removing particulate matter from the water. When used in combination with other mechanical filtration methods, a UV filter is a valuable aid for maintaining water quality.

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