How to Remove Red Algae From an Aquarium

Red algae can be difficult to remove from your aquarium. Red algae prefers water with a high pH and carbonate mineral hardness. Although this algae occurs naturally, if left unchecked it can cause severe damage to the health of fish. The minute organism is not a true algae, but a cyanobacteria appearing as a red slime on rocks, aquarium ornaments and plants. Controlling the pH balance of the water by keeping the aquarium free from rotting organic matter can help to maintain a healthier environment which may prevent red algae infestation.

Things You'll Need

  • Large pan
  • Nail brush
  • Red algae eating creatures
  • Algicide (optional)
  • Siphon
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Instructions

    • 1

      Boil some water in a large pan and add algae coated rocks and ornamental objects from the aquarium to the hot water, leaving them to soak until the water is no longer scalding hot. Do not add plastic items to very hot water.

    • 2

      Remove rocks and objects from the pan and scrub with a nail brush, rinsing them in clean water. Place items back in the aquarium. This will help to control the algae but will not eliminate it from other areas of the tank.

    • 3

      Control red algae by adding algae-eating shrimp or fish to the aquarium. These creatures can be purchased from aquarium supply stores and include the freshwater Siamese algae eater (Crossocheilus siamensis) or algae eating shrimp such as the glass shrimp (Palaeomonetes sp.). Shrimp are added to the aquarium at night when fish sleep, and can be used in large numbers though this will depend on the size of your aquarium. The supply store can give information and suggestions on how many shrimp to start with. No other source of food should be supplied at this time to encourage shrimp to eat only the red algae. Some shrimp may be eaten by the fish during the day and so they may need to be replenished. Shrimp will also nibble on aquarium plants so if you do not want this to happen, remove some plants, although not necessarily all of them. Algae eating crabs, fish and snails may be added to saltwater aquariums to maintain a healthy control of algal growth.

    • 4

      Clean the whole aquarium only if red algae has become a serious problem. Remove all fish and plants and place in a temporary tank. Remove all ornaments and rocks and clean in hot water. Siphon waste and debris from the tank bottom using an aquarium siphon. Remove gravel and wash in hot water only if necessary. Replace all items in the aquarium once cleaned and refill with clean water. This is an ideal time to add algae-eating creatures to the aquarium to prevent further infestation of red algae. Add fish and plants into the tank when ready.

    • 5

      Use chemical control of red algae if all else fails. Some of these solutions are copper-based algicides and may be purchased from aquarium supply stores. Use according to instructions.