How to Get Brown Moss Off Saltwater Tank Rocks

Algae growth in an aquarium is not uncommon, whether the tank is full of freshwater or saltwater. The "brown moss" you see growing on your saltwater tank's rocks is actually brown algae, and such growth is common in new tanks where the aquarium environment is in the process of stabilizing. Though this type of algae will usually disappear on its own, there are numerous methods you can follow to speed up the process if desired. These methods include manual cleaning and introducing various algae-eating marine animals to the tank.

  1. Shell Animals

    • Shell animals, such as marine snails, are ideal for removing brown algae from aquarium rocks whether the rocks are real or artificial. Though most snail species are herbivores, marine snails are omnivores. One snail per 5 to 10 gallons of water is enough to clean the tank efficiently. Recommended marine snails for the job include margarita snails and astrea snails. Tank water temperature when using marine snails should be between 72 and 80 degrees F. The tank's pH level should be stable as well, as unstable temperatures and pH levels will shock the snails. Low or nil nitrate and copper levels are also recommended.

    Frequent Water Change

    • Changing the water in your saltwater tank frequently will alleviate brown algae issues. Filling your tank with fresh saltwater on a frequent basis will remove the nutrients and dissolved fish waste from the water, which creates an inhospitable environment for brown algae to grow. Keeping your aquarium low on nutrients such as nitrate, phosphate and silicate levels is recommended. Frequent water changes will contribute toward an overall healthier aquarium environment and healthier fish.

    Brush

    • Removing algae manually is an option. Use a net or your hand to carefully remove affected rocks from the tank, and clean the rocks with water and a soft brush. Brush and rinse each rock until each is free of algae. This method works on artificial aquarium rocks.

    Additional Options

    • Use plants to get rid of brown algae in your saltwater tank, as plants compete with the algae for nutrients. A heavily planted tank will therefore severely reduce if not completely eliminate the tank's algae problems. If you decide to heavily plant your tank, it is important to control the tank's iron levels.

      Certain fish species enjoy consuming brown algae, such as suckermouth fish, mollies and the Siamese algae eater.