How to Clean Green Algae From the Side of a Tank

Green algae growing on your fish tank is actually a good sign: It means your tank is a healthy environment that can support life. While it's fine in theory, a large swath of algae can detract from your tank's appearance and reduce your enjoyment of the fish, especially if you can't see them through the green. Tanks with too much algae benefit from cleaning to reduce the green bloom; however, you probably won't be able to remove all of the algae from the tank by cleaning, and that's OK.

Things You'll Need

  • Algae scraper or scrubber
  • Siphon hose (optional)
  • Cup or bowl (optional)
  • Dechlorinator
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Instructions

    • 1

      Use an algae scraper or algae scrubber to remove the algae from the sides of the tank. Scape one side at a time, from the top of the tank down to the gravel line. If plants or aquarium decorations are in the way, pick them up and remove them while you clean the algae.

    • 2

      Remove 10 percent to 15 percent of the water in your tank. Use a siphon to remove water gently, or use a cup or bowl to scoop water from the tank. Take care not to remove any fish. Pieces of the algae that you just scrubbed off will come out with the water.

    • 3

      Get fresh water to replace the water you removed from the tank. Make sure the water is close to or equal to the temperature of the water you removed from the tank.

    • 4

      Treat the water with a dechlorinator to render it safe for the fish tank.

    • 5

      Pour or siphon the new water back into the fish tank.

    • 6

      Change out the aquarium filter as often as needed to ensure a clean tank. (This varies by your filtration system; your filter kit will tell you how often to change it.) Once you clean the tank, the leftover floating algae that was not removed with the water change will get sucked up by your filter.