September 9, 2019

UV Lighting and Your Decorative Pond

Though we specialize in the treatment of natural and non-lined bodies of water, we receive quite a few questions regarding decorative koi ponds. There are “good” and “bad” bacteria in all bodies of water. The bad bacteria releases phosphorus, which becomes a great food source for things such as algae and other aquatic nuisances. The good bacteria is great at breaking down organic material found in the pond. Using UV light wavelengths, or electromagnetic radiation, in the forms of UV sterilizers or clarifiers is a sure way of destroying unwanted bacteria in your decorative pond. The UV light is used alongside your other pond filtration systems. It cannot be used alone as it is not a filtration system. The UV light destroys the DNA of the bacteria, which makes the bacteria unable to function properly and eventually die.

Bacteria must pass directly in front of the UV light to be affected. The UV light is not able to distinguish the difference between the good and the bad bacteria, so any bacteria that passes over it will be affected. Due to the water flow in your pond’s filtration system, any of the good bacteria in your pond, whether added or naturally present, will eventually pass over this light. To keep the good bacteria safe, you must be sure that more of the bad bacteria is passing over the light rather than the good.

If you do decide to use a UV sterilizer or clarifier, there are ways to make sure you can safely add live beneficial bacteria. One option to help this situation is by shutting off the UV light for around 24 hours after you apply the product. This will give the live bacteria a chance to do its job before it has the potential threat of being affected by your UV light. You may also apply product straight to your filter. Most filters pull the water in, so the flow is passing beneath the lights. This will keep the added beneficial bacteria safely away from the UV light. We have an entire line of products geared towards decorative ponds and their upkeep. Our Koi Worx Pond Cleaner and Koi Worx Water Clear are two products that would be a good alternative to UV light. All of our decorative pond products do a great job at keeping your decorative pond clean and clear. There are no worries with the Koi Worx products, as they are safe for fish and other wildlife.


Using a UV light for long periods of time can have a negative impact on the natural ecosystem of a pond, as it kills off whatever bacteria passes over the light. A sterilized pond is not a healthy pond. To have a healthy pond, you must have a balance of good and bad bacteria. Both need to be present for the other to exist a proper life cycle. Though there are benefits of using UV light to eliminate some of the bad bacteria in your pond, it is generally much healthier and beneficial to your decorative pond if you were to use added bacterial products instead. If used correctly, you will find that you do not need to use UV light at all to have a clean, clear pond.

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