How to Clear Up an Algae Bloom in a Fish Aquarium

Algae encompass a vast group of photosynthetic, complex-celled organisms that come in a variety of colors, from brown to green and red. An algae bloom is a sudden, dramatic increase in a fish tank̵7;s algae population that results in cloudy water and a potentially toxic environment for your fish and plants. Control an algae bloom safely to clear the water without harming the other living things in the tank.

Things You'll Need

  • Plastic buckets
  • Small fish bowl
  • Plastic bin or sink
  • Magnetic algae scrubber
  • Razor blade
  • Siphon
  • Gravel vacuum
  • Dechlorinated water
  • Snails or algae-eating fish
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Instructions

  1. Cleaning the Tank

    • 1

      Unplug the filter, lights and anything else electrical on the tank to prevent a potential shock.

    • 2

      Remove the fish from the tank and place them into a plastic bucket or small fish bowl with water properly conditioned for them. Place the plants and decorative items into a plastic basin or clean sink.

    • 3

      Scrub the plants and decorative items with a magnetic algae scrubber. The scrubber removes the algae from these items without the need for potentially toxic cleansers or detergents. Rinse the plants and decorative items under a cool tap.

    • 4

      Scrub the sides of the tank, the light, and the aquarium̵7;s base with the magnetic algae scrubber. Continue to scrub the surfaces until the majority of the algae are gone.

    • 5

      Remove any difficult algae with a razor blade. Holding the razor blade at a 30 degree angle, scrape it off the tank̵7;s sides, paying attention to avoid scratching or damaging the aquarium's surface.

    • 6

      Remove at least 30 percent of the aquarium̵7;s water with a siphon. Siphon the water into a plastic bucket and pour it down the drain or toilet. It is not necessary to remove all of the tank̵7;s water to control the algae blooms.

    • 7

      Clean the gravel, pebbles or other substrate with an aquarium gravel vacuum. Run the vacuum back and forth directly above the gravel to remove any excess fecal matter, decaying food and algae from the substrate. Depending on the model used, the gravel vacuum requires a sink or a plastic bucket to siphon the debris into.

    • 8

      Refill the tank with dechlorinated water -- available at pet stores -- and reintroduce the plants, decorative elements and fish to the tank.

    Preventing Future Algae Blooms

    • 9

      Introduce snails or algae-eating fish to the aquarium. Black mollies, Siamese algae eaters and rosie barbs all consume small amounts of unwanted aquarium algae.

    • 10

      Remove any uneaten food immediately from the tank. The food provide extra nutrients, including potassium and nitrogen, the algae require to thrive.

    • 11

      Avoid overcrowding the fish tank. Excessive numbers of fish means more food and fecal matter, two factors that contribute to algae blooms. As a rule, provide at least 1 to 3 inches of space per fish in the tank.