How to Remove Black Algae From a Salt Water Pool


Black algae can ruin the pristine look of a pool. Black algae can form in either regular or salt water pools, and it often forms in the cracks of pool surfaces, especially in cool, shady areas. It sometimes creates a heavy, slimy layer. Although black algae doesn't have any effect on the clarity of water, it does make the pool appear to have black spots on its surface.

Things You'll Need

  • Stiff pool brush
  • Algaecide specific for salt water pools


  • Brush the algae thoroughly with a stiff pool brush to “break open” the slimy layer. Failing to do this may prevent the treatment from working as chemicals won't be able to penetrate the algae as well.

  • Shut off the pool pump.

  • Pour algaecide over the black algae according to the directions on the bottle and leave it overnight.

  • The next day, brush away and discard all the dead algae spots.

  • Repeat the process if you continue to see some black algae spots.

  • Restart the pool pump for circulation and adjust the pool's salt levels.

  • Make sure you maintain proper salt water chlorination levels as it helps kill bacteria and prevent black algae from growing back.

Tips & Warnings

  • Maintaining good pool circulation can prevent black algae because it grows when the water has low salt content and/or when pool chemicals are unbalanced.
  • This treatment is not for vinyl-lined pools as it may damage the vinyl layer.
  • Do not swim in the pool during the black algae treatment.

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  • Photo Credit water forms in pool image by JoLin from
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