How to Remove Algae From Gunite Pools

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Things You'll Need

  • Wire-bristle brush

  • Algaecide

  • Pool shock

  • Pool vacuum

  • Garden hose

  • Pressurized nozzle (if needed)

Gunite pools have a rough and porous surface, which algae can grow on and stain. If you have a gunite pool, take proper care of it by maintaining the water circulation, filtration, water chemistry and chlorine. "Shock" the pool as needed. Shocking the pool means putting in oxidizing chemicals to rid the water of bather waste. If algae has already grown and taken over, use an algaecide and pool shock to kill the algae. There are some steps you can take to kill the algae in your pool and on your pool equipment.


Step 1

Thoroughly brush the pool using a wire-bristle brush. Place all items that have come in contact with the contaminated water, including the brush, in the shallow end of the pool. This will kill any algae off the items so they do not re-contaminate the water after it has been cleaned.

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Step 2

Add an appropriate amount of algaecide to the water, according to the manufacturer's instructions.


Step 3

Shock the pool at least five hours after adding the algaecide. Use 2 lbs. of shock per 10,000 gallons of water.

Step 4

Wait until the next day. Remove the pool brush from the shallow water and thoroughly brush the pool in the morning and evening.


Step 5

Fill the pool to its highest point the next morning. According to the Pool Manual website, this allows you to bypass the filter and vacuum the algae to a waste line. You do this because algae can live on the inside walls of the filter, which could allow it to get picked up by water during circulation and re-enter and re-infest the pool.


Step 6

Remove the pool vacuum from the shallow water. Vacuum everything out to the waste line. Put all vacuum items back in the shallow end of the pool and fill the pool to the standard operating water level (half way up the skimmer) with a garden hose.

Step 7

Brush the entire pool that evening and again, at least once a day, for the next two days.


Step 8

Remove everything from the shallow end of the pool, assuming the algae appear to be gone. Brush the entire pool and, if a metallic algaecide was used, add a metal sequestering agent to the water to rid it of any lingering copper.

Step 9

Brush the entire pool the next day (Day 7).

Step 10

Wait another day (Day 8) and add 1 lb. of shock per 10,000 gallons of water.


If you are unable to vacuum your pool straight to a waste line, do not fill the pool up to its highest point and do not add extra algaecide and shock. Instead, the Pool Manual website suggests adding the required amount of algaecide and 2 lbs. of shock per 10,000 gallons of water. Vacuum the pool using your filter. Stop often during the process to clean the filter. After vacuuming, clean the filter again. If you have a sand or DE filter, simply backwash it. If you have a cartridge filter, clean it with a garden hose and pressurized nozzle.


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