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Remove Algae from Your Pool

Remove Algae

Swimming pools are a lot of fun but occasionally can develop water problems, such as algae, that can discourage you from enjoying them. Here are instructions on how to remove pool water algae.


Preparation

remove algae

To remove algae from your pool water, you may need to use some chemicals. Before using swimming pool chemicals, read all product labels for directions and safety precautions. If you have additional questions or problems, discuss pool maintenance with a Lowe's associate or call a professional for help. In addition, pool experts recommend that you:

  • Store products in their original containers in a cool, dry and well-ventilated area out of the reach and sight of small children.
  • Never smoke while using pool chemicals.
  • Always add chemicals to the water — never add water to the chemicals.
  • Never add chemicals to the pool while someone is in the water.
  • Never mix chemicals unless the label specifically instructs you to do so.
  • Always wear rubber gloves when handling chemicals.


Solving Algae Problems

green algae in a pool

Algae are tiny, microscopic plants that enter a pool by rain, wind or fill water. Green algae are free-floating, mosslike debris in the water. Black and mustard algae can be identified by simply running a hand over a sidewall of the pool. If the wall is slick or oily to the touch, it’s probably from the growth of one of these types of algae. The causes of pool algae growth include:

  • Inadequate, free and available chlorine levels caused by a heavy rain, a lot of swimming or poor maintenance
  • Too high of a pH level, preventing chlorine from killing the algae
  • Insufficient cleaning or brushing of pool surfaces, leaving the surfaces dirty and vulnerable to algae growth


Treat Green Algae


Step 1

Verify that the pool filter is clean and running properly.


Step 2

Test the water to make sure the pH level is between 7.2 and 7.6 and adjust as needed.


Step 3

Add an algaecide following the label directions and allow it to work overnight.


Step 4

The next day, brush and vacuum the pool surfaces. As needed, backwash or clean the filter to remove the collected algae and debris.

  • Backwashing is the process of reversing the water flow back through the filter to remove debris.

Step 5

For a heavy growth of green algae, perform a second algaecide treatment following the product instructions.


Step 6

As needed, retest the water for pH and total alkalinity. Black algae grows on pool walls and floors as a thick mat that quickly can ruin pool water. Mustard algae appears as yellow or orange spots, typically found on shaded walls and floors. It can be brushed off easily but will likely return if not treated properly. Mustard algae can be resistant to chlorine and some compounds in regular algaecides, so a special algaecide is required to eliminate it.



Treat Black and Mustard Algae


Step 1

Test the water to make sure the pH level is between 7.2 and 7.6 and adjust as needed.


Step 2

Brush and vacuum the pool surfaces using standard pool cleaning tools.


Step 3

Backwash the filter to remove as much debris as possible.


Step 4

Add pool shock following the manufacturer’s instructions.


Step 5

Add a specialized algaecide following the label directions and allow it to work overnight.


Step 6

The next day, brush and vacuum the pool surfaces again. As needed, backwash or clean the filter to remove the collected algae and debris.


Step 7

Repeat the process as needed to thoroughly remove the algae.


Step 8

After the pool water is clear, chemically clean the filter with a filter cleaner.


Step 9

As needed, retest the water for pH and total alkalinity.


Project Information

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*Time and Cost are estimated.