How to Stop Algae in a Planted Tank

Algae can overwhelm a planted aquarium very quickly. It depletes the water of oxygen, clogs equipment, coats the glass and reduces visibility, and competes with plants for light and nutrients. While some algae is not a problem, too much is. You shouldn't use algaecides in a planted tank, because it would kill or damage your plants and some fish, but you can keep algae under control with other methods.

Things You'll Need

  • Thin plastic hose
  • Bucket
  • Algal scraper
  • Aquatic plants
  • New tank lightbulbs
  • Grazing fish and aquatic snails
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Instructions

    • 1

      Clean your tank. Remove and replace about one-quarter to one-third of the water in the tank. Siphon off debris into a bucket with a hose as you remove water, and scrape excess algae off the sides. Repeat about once or twice a month. Remove any dead fish or decaying vegetation as soon as you notice them.

    • 2

      Introduce more plants if there is space. The more aquatic plants you have, the fewer nutrients available for the algae. Extra plants also help keep the water oxygenated and provide more habitats for your fish.

    • 3

      Increase the light intensity in your tanks by replacing old lightbulbs or installing lighting equipment. Algae need light, but so do the aquatic plants. Normally, more light favors the growth of your plants most, and they compete with the algae.

    • 4

      Introduce grazers. Some species of fish, such as dwarf catfish and sucker loaches, and snails eat mostly algae and keep it under control.

    • 5

      Stop overfeeding your fish. Uneaten fish flakes are full of nutrients, which encourage algal growth. Don't give your fish more than they can eat within a few minutes. If you want to give them a treat, try live food such as daphnia, which might even eat some algal spores before they themselves are eaten.