How to Kill Brown Algae in an Aquarium

Brown algae can be an ugly and harmful problem in your fish tank. Diatom growth can spread over the walls, rocks and decorations of your aquarium and steal nutrients from your aquatic plants. Brown algae commonly grows in newly established tanks, but it can appear in any aquarium that has too many nutrients in the water. Getting rid of brown algae can take time, but by adding a few chemicals, filters and fish, you should be able to get the problem under control.

Things You'll Need

  • Aquarium siphon
  • Reverse osmosis or deionized water
  • Adsorption resins
  • Ultraviolet sterilizer
  • Algae-eating fish or snails
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Instructions

    • 1

      Chance your tank's water. Use an aquarium siphon to remove about 20 percent of the tank's water. Make sure to move the siphon through the gravel and substrate to remove fish waste, which can feed the algae. Replace the water using reverse osmosis or deionized water; such techniques use specially filtered water that won't contribute nutrients to algae growth.

    • 2

      Add phosphate adsorption resins to your tank. These chemical filter medias, which can come in pellets or filter pads, will remove phosphates and silicates from your aquarium, helping further starve the algae.

    • 3

      Install an ultraviolet sterilizer outside your tank. This is another water filtration method that will kill brown algae. The UV rays, which are as natural as sunlight, won't harm the fish or plant life but will kill bacteria and algae floating in your tank's water.

    • 4

      Purchase an animal that specializes in eating algae and put it in your aquarium. A few aquatic species thrive on algae, including a freshwater suckermouth fish such as the ancistrus fish or the Siamese algae eater fish. In saltwater tanks, add algae-eating snails such as the margarita snail. All such animals will work like vacuums, eating algae off rocks and tank walls.