How to Get Rid of Algae in a Saltwater Aquarium

Small amounts of hairlike green algae in your saltwater aquarium are a sign of a flourishing tank ecosystem, but an infestation of aggressive algae is a threat to the health of your saltwater tank. Green algae is normal in saltwater aquariums, and many fish feed off free-floating algae spores. Algae that covers the glass of your tank, or algae that is slimy, red, blue or black, is a dangerous tank problem that saps nutrients and jeopardizes your filtration system. Removing excess algae from your saltwater tank is necessary to maintain the health of the tank.

Things You'll Need

  • Phosphate removal medium
  • Protein skimmer
  • Ultraviolet sterilizer
  • Aquarium scraper
  • Aquarium vacuum or siphon
  • 5-gallon bucket
  • Saltwater mix
  • Algae-feeding fish
  • Live plants
Show More

Instructions

    • 1

      Rinse live coral and rocks in filtered water before adding them to your tank. Algae spores often cling to rocks and coral and later take hold in your aquarium.

    • 2

      Limit the aquarium's exposure to natural and artificial light sources. If possible, position your aquarium so that it does not face a window. Block direct sunlight with blinds or shades. Keep tank lights on for eight hours a day and turn the lights off overnight.

    • 3

      Insert a phosphate removal medium into your water filter chamber. Phosphorus is a main food source for algae, and phosphate removal media cartridges, bag or pellets filter out phosphate as the water cycles through the filter.

    • 4

      Install a protein skimmer inside your tank. Protein skimmers filter saltwater through a chamber that traps organic compounds and amino acids that would otherwise serve as food for algae.

    • 5

      Install an ultraviolet water sterilizer in your saltwater tank. UV sterilizers affix to the existing tubing or piping of your filtration system and sterilize microorganisms as water flows over the UV source. The UV exposure kills algae spores as well as other microorganisms that threaten the health of your tank.

    • 6

      Use an aquarium glass scraper to remove algae from the walls of your tank. Vacuum the gravel with an aquarium vacuum to remove algae that has settled on the gravel. Siphon the water into a bucket and refill your tank with filtered tap water mixed with saltwater mix according to the package instructions.

    • 7

      Adjust the water flow through your circulation system to increase the currents near the area affected by algae.

    • 8

      Introduce fish and other sea creatures that feed off algae. Tangs, blennies and shrimp are efficient algae-feeders that control growth.

    • 9

      Add more live plants to your saltwater tank. Live plants compete with algae and restrict their growth. Kelp, maiden's hair and mermaid's fan are suitable for saltwater tanks.

    • 10

      Remove dead fish or plants immediately to prevent decay. Decaying live material serves as food for algae.