How to Remove Algae Blooms From a Fish Tank

Algae occurs when there is an imbalance in your aquarium's water chemistry. Most fish tanks contain algae spores, and when there are high levels of excess nutrients, phosphates, uneaten food or decaying waste present to feed the spores, algae can become a problem and rapidly take over your tank. Remove growths on glass with an algae magnet, scraper or rough cloth, and scrub tank decorations with a toothbrush. A suspended algal bloom in the water may require a commercial algaecide solution if it turns the water green.

Things You'll Need

  • Cloth
  • Algae magnet
  • Algae scraper
  • Toothbrush
  • Algaecide solution
Show More

Instructions

    • 1

      Attach an algae magnet to the sides of your fish tank and use it every day to prevent buildup on the glass. An algae magnet consists of two magnetic blocks with lightly abrasive surfaces. Hold one block to the glass outside your tank, and place the other in the water, against the glass inside, until the two blocks slide together magnetically. Move the outer block across the glass, and the abrasive surface of the internal magnetic block will scrape away algae.

    • 2

      Wipe away new algal blooms with a soft cloth during a partial water change or full tank clean. Algae is easiest to remove from glass when wet, so do not allow the aquarium to dry out or you will require a scraper to tackle stubborn, dried-on deposits.

    • 3

      Scrape away hardened crops of algae with a professional tool. Commercial algae scrapers are multi-functional tools for the effective removal of algae growth from flat aquarium surfaces. Scrapers vary in design, but usually feature a soft cloth surface, abrasive pad and a hard plastic-edged blade for stubborn residue and hard-spot algae deposits.

    • 4

      Remove algae on tank ornaments using a small, stiff-bristled brush. Scrubbing is time consuming but you can make the job easier by soaking decorations in a bucket of hot water for 20 minutes before brushing away algae with a toothbrush. Some types of less adhesive algae rub off easily under running water after a hot soak.

    • 5

      Dose your aquarium with a chemical algaecide treatment to remove suspended algal blooms in the water. Prepare the solution according to the manufacturer's instructions, and add to your water. Copper is often the active ingredient in chemical-based algae inhibitors, but it is dangerous to some fish species and marine invertebrates. Check that the copper level in your chosen algaecide is compatible with your fish before adding a commercial chemical treatment to your aquarium.