How to Use Black Algae Killer


A black algae infestation in a home swimming pool can be a nightmare for homeowners. It can also infect home aquariums. Simply brushing away the algae won't do the trick. Like dandelions, black algae must be killed at the roots, which grow on the surface of the pool or aquarium. An algaecide is recommended, but there is more to the process than simply pouring it in and watching it work.

Things You'll Need

  • PH tester
  • Filter pressure gauge
  • Brush or scrubber
  • Chlorine tablets
  • Algaecide
  • Vacuum
  • Inspect your pool. Check the pH level of the water in your pool to make sure that it is normal. Check the pump pressure on your filter. If the filter is not working or has too little pressure, then your filter will allow in more algae after you have cleaned the pool.

  • Scrub the pool with a brush on the visible algae. Scrub vigorously. While this does not kill the roots of the algae, it does make it easier for the chlorine and algaecide to penetrate the surfaces of the walls.

  • Turn off the pump. The pump and filter will work against you if they are on because they will filter out the excess chlorine and algaecide that you will need in combating the problem.

  • Use chlorine tablets near the affected areas. This will provide an initial treatment of the black algae and remove nearly all of the visible algae. Drop the tablets in the pool near the infected areas and allow them to dissolve fully.

  • Use algaecide on the infected areas. Do not dilute with water. The most effective way to combat black algae is to use concentrated algaecide. Pour in 12 ounces of algaecide near the infected areas per 10,000 gallons of water. Let the algaecide work overnight.

  • Turn on the pump. Firing the pump up again will allow the algae that has been killed and is in the pool water to be sucked into the filter.

  • Brush the surfaces away again to clear the walls of dead algae. This will fall into the pool water and be sucked away by the filter.

  • Superchlorinate the pool. Adding more than the usual amount of chlorine will help to prevent the reappearance of the algae.

Tips & Warnings

  • If your algae problem is in an aquarium, remove the fish and other living creatures before treating with algaecide, and do not use chlorine.
  • Repeat steps 2-5 if necessary or if the algae infestation was pervasive.
  • Repeat these steps monthly to ensure the algae does not return.
  • Algaecide is harmful to fish and other living objects. Wait 24 hours after treatment before using the pool or adding fish back into the aquarium.
  • Do not swim in the pool during treatment.
  • Remove all living things from an aquarium if treating it for black algae.

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