How to Troubleshoot a UV Pond Light

turtles on a rock in a pond with a UV light
  • 1-3 hours
  • Beginner
  • 25-75
What You'll Need
Kitchen towels
Electronic ballasts
UV pond light bulbs

Installing a UV pond light into your garden installation is a fantastic way of reducing pond algae. If your pond has UV pond lights fitted but algae still seems to be growing at a steady rate, there may be a problem with your units. Algae build-up is most easily noticed by water changing color to a dirty green.

Below are steps to solve any problems with your UV pond light set-up.

Step 1 - Bulb Replacement

If a light isn’t working, remove the bulb and try installing a new one. There is, of course, a chance that there is an electrical fault or connection problem but changing a bulb will eliminate one possible route of remedy and is particularly easy to do.

Step 2 - Check Ballast

Ultraviolet lighting is fitted with electronic ballasts. These can often become damaged due to water seepage, power surges or aging.

Electronic ballasts are easy to purchase from any major DIY center and are equally as simple to fit.

Step 3 - Check Supply

Bulb or ballast replacements are usually the two most common malfunctions on UV pond lights. If changing either of these components has failed to solve the problem, it is worth checking the electrical supply to the unit.

Test the plug point by plugging a different electrical appliance into it and seeing if it works. If it doesn’t, check the relevant circuit box to see if the switch has "tripped."

Once you have established that the plug point is operational, you can proceed to check the quality of the power cord and see if there are any snags, tears or breakages.

You may also consider checking the wiring of the plug to see if anything has become loose. While the plug casing is open, change the fuse as well. If the wiring is faulty in any way, dispose of the lamp and purchase a new model.

Step 4 - Clean the Protective Sleeve

The protective sleeve that protects the lighting section from contact with water can often become stained or dirty. This affects how brightly the UV lamp can shine. Remove the sleeve and clean thoroughly using vinegar and some kitchen towels. Sleeves are usually composed of quartz and can be particularly expensive to replace so handle carefully at all times to avoid breakages.

Step 5 - Check Placement

The pond pump and the UV pond lighting unit should be as far apart as possible. When the pump circulates water, the UV light will have little chance of having any effect on it if it is in close proximity. Keep pumps and UV lights at opposite ends of a pond for maximum effect.

Step 6 - Age

Sometimes, a UV pond light will stop working simply because it has aged. If your light has been struggling for some time, you may need to purchase a new model.