Remove Yellow Water Line or Scum Line from Boat Hull

Quickly remove the yellow water line / scum line from fiberglass boat hull.


This is a short demonstration video that shows you how to remove the ever-so-common water line from a boat’s hull using the Bio-Kleen Oxidation Remover hull cleaning product and a Boat Body Brush. Materials Needed:


  • 1. Spray Bio-Kleen Oxidation Remover onto area affected with yellow water line stains. Allow product to dwell for extremely hard to remove stains.
  • 2. Agitate lightly with a Boat Body Brush with medium to soft flagged tip bristles
  • 3. Rinse




The yellow water line or scum line is a very common problem with boaters and it shows up quite frequently. The water line or scum line on a boat hull can be caused from several different factors within your waterway and some bodies of water can produce a healthy water line in a matter of days or even hours. The causes of these yellow water stains include: high mineral content, such as iron, in the water that leaches out of rocks or soil, surface pollutants such as diesel, and organic material such as algae or bacteria. Many port-rivers or commercial waterways are well known for causing a yellow water line on your boat hull rather quickly.

The Bio-Kleen Oxidation Remover is a great all-purpose, biodegradable hull cleaning product but it specializes in specifically removing the yellow water line stain from fiberglass boat hulls. Also removes algae and scum lines, scale build-up, chalking, and dissolves stains from water minerals. It wipes or rinses away freely and leaves the surface clean. It is excellent for removing chalking and stains within dry/indoor storage where rinsing is not permitted. Another special attribute is its ability to easily remove spider droppings from boats and rv exterior.

Watch in this video as the Bio-Kleen Oxidation Remover is sprayed onto the yellow water line stain on the boat hull and the stain instantly disappears. It really is that easy and works that fast. If your boat hull has heavier build up from water minerals, algae or a thick scum line a longer dwell time and agitation from a boat body brush may be needed. Rinsing is recommended though may not be needed for dry storage areas and minimum build up. After removing the yellow water line and stains with the Bio-Kleen Oxidation Remover, apply a boat wax to create a protective barrier against the water stains and a brilliant shine.


Back to DIY Guide | How To Cleaning and Detailing Tutorials