Algae on a boat dock can make walking surfaces slippery and leave stains that are harder to remove over time. The right cleaning method depends on the dock’s material, the type and extent of buildup, and the cleaner’s instructions. Start by identifying the surface and checking any care guidance from its manufacturer. Then use the least aggressive method that works, protect nearby water, and avoid scrubbing or chemicals that could damage the dock or harm aquatic life.
Recognize Common Algae Buildup
Algae often appears as green, brown, or dark film on damp, shaded parts of a dock. It can collect near the waterline, between boards, on ladders, and in areas with limited airflow. Slimy growth may feel slick underfoot, while older buildup can dry into a stubborn coating. Not every stain is algae, so check whether the surface feels slippery and whether the discoloration spreads in persistently wet areas.
Dock conditions influence how quickly growth returns. Shade, standing water, debris, and limited circulation can keep surfaces damp. Remove leaves and other material regularly, and look for drainage problems that leave water trapped on or beneath the dock. If algae returns quickly in the same spot, address the moisture or debris source as well as cleaning the visible growth.
Choose a Surface-Safe Method
Identify whether the dock is wood, composite, concrete, or another material before cleaning. Follow manufacturer care instructions where available, especially for composite decking and treated wood. Sweep away loose debris, then test your cleaning method on a small, inconspicuous area. A soft-bristle brush, water, and a cleaner approved for the surface are often a safer starting point than a stiff brush or harsh chemical.
Use only the amount of cleaner and scrubbing needed to loosen the growth. Rinse as directed, while keeping runoff and concentrated products out of the lake or other waterways. Do not mix cleaning products, and avoid bleach or strong acids unless the dock manufacturer specifically permits them. A pressure washer can scar wood, damage composite surfaces, or force water into joints, so check the surface guidance and use appropriate low pressure and distance if permitted.
Clean With Safety in Mind
Work when the dock is stable and conditions are calm. Wear slip-resistant footwear and gloves, keep children and pets away from the work area, and do not lean over the water while scrubbing. Clean a small section at a time so you can control rinse water and maintain a safe path. If you use a ladder or reach near an edge, follow proper fall-prevention practices and avoid working alone in a risky location.
Before applying any cleaner, read its label for surface restrictions, protective equipment, dilution, and disposal directions. Use a product labeled for the intended job and compatible with the dock material. Avoid washing chemicals directly into the water. If local rules or the product label leave you unsure about runoff, pause and ask a qualified dock-cleaning professional about a suitable approach.
Know When to Call a Professional
Professional cleaning may be a better option when algae covers a large area, returns despite routine care, or has made access to the dock unsafe. Consider help if the surface is delicate, damaged, difficult to reach, or subject to specific manufacturer requirements. A cleaning professional can assess the material and buildup, select an appropriate method, and help limit unnecessary wear and runoff.
Stop DIY work if boards feel loose, the dock shifts, the growth extends below the waterline, or you cannot clean without working close to an unprotected edge. Also seek advice if the stain does not respond to a surface-safe method; it may not be algae, and stronger treatment could cause damage. Wasatch Dock Care serves the Salt Lake City area for customers who need help assessing and cleaning dock buildup.
For safer algae removal, identify the dock material, start with a gentle approved method, and control cleaner and rinse water. Regularly clearing debris and checking damp areas can help you spot regrowth early. If the dock is slippery, extensive, delicate, or difficult to reach, contact a dock-cleaning professional to discuss a suitable cleaning plan.