How to Remove Algae From Slate

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Things You'll Need

  • Plastic bucket

  • Mild dishwashing liquid

  • Nylon scrub brush

  • Toothbrush

  • Rag

  • Non-porous gloves

  • 1 cup bleach

Some pools and fountains are made of slate.

Slate lends a natural, outdoor feel to an area and many homeowners are choosing to use slate in place of tile in many areas of the home. Adventurous decorators are using slate for flooring, fireplaces, fountains, decorative walls and more. While slate looks beautiful, its porous surface can provide a safe haven for dirt and grime. Slate used in kitchens and bathrooms can become exposed to excessive moisture conditions. If algae spores become introduced to the grime and moisture, they can spread rapidly and ruin the look of your stone. Fortunately, removing algae from slate is fairly straightforward.


Step 1

Fill a bucket with with warm, soapy water. Use a mild dishwashing soap that does not contain acids such as lemon or lime.

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Step 2

Dip a nylon scrub brush in the soapy water. Scrub the slate vigorously to remove the algae. If necessary, dip a toothbrush in the soapy water and use it to reach any difficult nooks or crannies in the slate.

Step 3

Rinse the slate, the bucket and the cleaning brushes with cold water. Dry with a rag afterward.

Step 4

Slip on a pair of non-porous gloves, made from a material such as rubber or plastic. Mix 1 cup bleach with 1 gallon of water in the plastic bucket.


Step 5

Scrub the slate with the bleach solution to disinfect the stone and kill any remaining algae spores. Use the same nylon scrub brush, toothbrush and cleaning techniques as before.

Step 6

Rinse the slate, the bucket and the cleaning brushes with cold water. Dry with a rag afterward.


Do not use acid-based cleaners on slate.


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