How to Kill Black Algae With Bleach in Drained Swimming Pools

The best method for cleaning a drained in-ground pool to be free of black algae stains is to acid-wash it. If you're an above-ground pool owner who has drained the pool and left it without water for some time, chances are you will have to replace the liner because it has shrunk. If you fill it back up with water, the pool walls can buckle, making cleaning the liner a moot point. If you're looking for an alternative to an acid wash for your in-ground pool or still insist on draining and your above-ground pool and cleaning your vinyl liner, a bleach solution is your best option to kill black algae.

Things You'll Need

• Rubber gloves
• Respirator
• Pump sprayer
• Bleach
• Garden hose
• Stiff-bristled brush

Show More

Instructions

1. • 1

     Fill up the pump sprayer with one part bleach to 10 parts water. You need a strong bleach solution to kill the algae.

   • 2

     Spray the pool wall with the garden hose. Scrub the algae with the stiff-bristled brush first without the use of bleach. This will scrub the protective membrane off the black algae, which will allow the bleach to penetrate into the algae heads. Work in small sections.

   • 3

     Apply the bleach solution with the power washer. Scrub away the black algae with the stiff-bristled brush. Work your way around the pool until all the black algae has been scrubbed in the bleach solution. Repeat if necessary and refill the power washer when empty.