How to Remove Red Algae From a Fish Tank

Algae is a big term; it refers to a wide variety of organisms, many of which are not related. Several types of algae the occur in both freshwater and saltwater aquariums are called "red algae." Even though the freshwater variety is a protist and the saltwater variety is a cyanobacteria, treatment is similar.

Things You'll Need

  • Aquarium scrubber pad
  • RO water or DI water
  • Bucket
  • Aquarium vacuum
  • Black plastic trash bags
  • UV or diatom filter
  • Algecide (available at pet shops)
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Instructions

    • 1

      Physically remove the algae with an aquarium scrubber pad.

    • 2

      Perform regular water changes. Using RO or DI water will ensure that nutrients are not added to the tank. Algae need nutrients to grow. Also, use a gravel vacuum (an wide-mouth siphon) so you can clean the gravel as well.

    • 3

      Cover the tank in plastic bags for several days if the problem persists. This will block out all light and kill the algae. Do a water change immediately afterwards, as the dead algae can rot and foul the water.

    • 4

      Add specialized filters if the problem continues. UV sterilizers and diatom filters can kill and filter out algae in the water column.

    • 5

      Consider an algaecide, as a last resort. Follow the manufacturer's instructions to the letter. Algaecide is toxic to plants and invertebrates, and not particularly healthy for fish either.