How do I get green algae off my Trex fence?
Green algae can grow on virtually any surface where it has a food source, typically particles of decomposing materials such as small flecks of decaying leaves or grass that have stuck to a surface. To get green algae off your fence, there are several solutions.
A simple, non-toxic approach is to scrub your fence with a mixture of vinegar and water and let it sit on the fence for an hour before hosing it off. This will typically kill most of the algae. Since vinegar is acidic, it could affect sensitive plants, so you may want to consider covering them before cleaning your fence. If this method doesn't take care of the problem, a more aggressive home remedy to remove the green algae off your fence is to mix eight parts water, eight parts peroxide, and one part Dawn dish soap. Scrub the mixture onto the surface of the fence and hose it off. Since peroxide is a strong chemical, follow recommendations for safety precautions and treatment. You may also want to make sure your work won't negatively affect the plants around your fences. Take measures to protect them before applying the solution. Water your plants before and after the cleaning project. If possible, cover the plants during the operation as well.
An additional option is to use a product called a deck brightener which contains oxalic acid (a wood bleach). This will typically kill all of the algae but it does have the propensity to lighten the material it is used on, so be aware your fence color may alter. Here is a video that shows how to use oxalic acid solutions as a cleaner. Although the video was tailored to the Trex traditional decking products, fencing is made of the same material so the application is the same.
If you want to freshen the color of your fence after the cleaning project, you can paint or stain your fence. Trex is porous so paint or stain will adhere to the material. It's always a good idea to test any of these solutions on a small area of your fence to make sure you get satisfactory results before you clean the entire fence. You can visit our Fence Care Guide on our website for help on a variety of maintenance situations.