How to Remove Algae From Rocks

Algae forms on rocks and stones in just about any type of water, from oceans to aquariums. This plant life is beneficial for the most part, as it provides oxygen and can be a food source for marine life. But it can also give off carbon dioxide as it decays. If you want to restore the oxygen balance in your aquarium, removing the algae may be necessary from time to time.

Algae can grow in almost any wet environment.
  1. Fill a bucket or sink with hot water.
  2. Add ΒΌ cup of salt for each gallon of water. Put the rocks in the container, and let them soak for 30 minutes.
  3. Take the rocks out of the bucket, and rinse them under warm running water. Rinse for a minimum of one minute to ensure that all traces of salt are washed away. Residual salt may affect the pH level of aquarium water.
  4. Scrub the rocks with a stiff-bristle nylon brush. Using clean water, rinse any remaining algae off the rocks.
  5. Return the rocks to your aquarium.

Things You Will Need

  • Bucket -- optional
  • Hot water
  • Salt
  • Stiff-bristle brush


  • If the rocks are along the edge of a pond, pour hot water over them and scrub them with a stiff-bristle metal brush. The algae should be easy to remove.

About the Author

Kenneth Coppens began his freelance writing career in 2008. His passions in life consist of extensive personal research on food, gardening and finding natural and eco-friendly alternatives to nearly all aspects of life.

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