Updated at: 04-01-2023 - By: Sienna Lewis

Having a backyard pool is the best way to enjoy the summer sun. When the good times are ruined by algae, it’s time to do something about it. The following are instructions on how to remove and prevent algae from forming in your swimming pool.

What Are Algae?

There are many different kinds of algae. To sustain themselves, they rely on the sun, water and carbon dioxide. In pools, algae stick to the walls, floors, or steps and float in water.. It’s important to cure algae as soon as possible, ideally at the earliest opportunity. Algae in swimming pools aren’t usually dangerous. However, E. coli, parasites, and salmonella may be present in the food.

Poor filtration, out-of-balance water, low or irregular chlorine levels, and poor water circulation can all contribute to the growth of pool algae.

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The most prevalent types of algae are green, dark green, yellowish green, and blue-green. Green algae are slick.

Black algae, which resemble mold but are actually bacteria, can grow in a swimming pool. It’s impossible for black algae to float in water. Their roots can grow into the grout and fractures of tile, which they adhere to in patches, or they can attach themselves to smooth surfaces like concrete.

Some other algae include yellow algae, which are a muddy yellow or brownish tint, as well as pink algae, which like black algae are bacterium-based.

Algae are a diverse category of basic organisms, and there are numerous varieties. All of these species, like plants, use sunlight to produce food from carbon dioxide and water in the process known as photosynthesis.

Algae, such as the green ones, are closely connected to plants. Algae, like plants, requires a lot of water in order to thrive. Green algae, on the other hand, is devoid of stems, leaves, or even genuine roots.

Soil contains algae, which disperses its spores into the atmosphere, where they are picked up by the wind and deposited on your roof, deck, driveway, and other surfaces around your house. Your porch, patio, awning, siding, fence, walkway, and even your outdoor furniture might be infested with algae.

Preventing Algae Growth in a Pool

Regular maintenance is required to keep algae from growing in your pool. Algae control can be made easier if you follow the suggestions listed below.

  • On a regular basis, check the water balance.
  • If you want to keep your water clean, ensure sure your filtration system is working properly and circulating the water as it should.
  • Every week, shock the pool with a dose of chlorine. Using a shock treatment can help clear up hazy water, which may be an early sign of algae growth. Chlorine shocks, such as calcium hypochlorite or dichlor, are commonly used in swimming pools. When calcium hypochlorite is mixed with water, it creates a calcium-chloride solution. Before introducing it to the pool, it’s dissolved in water. Tablets and granular forms of chlor are also available. Chlorine and cyanuric acid are also added to the water during the process. Before using an algaecide, shock should be applied. Using them at the same time will have no effect.
  • Regularly apply an algaecide. Algaecides can be effective if applied correctly.
  • Make sure the pool, including the steps as well as the walls and the floor, is cleaned on a regular basis. The type of pool brush you should use depends on the type of pool material you have. Using a wire brush to clean acrylic, fiberglass, vinyl-lined, or painted pool surfaces might cause harm.
  • Regularly clean the filter, pump, and skimmer.
  • Vacuum the pool at least once a week. A skimmer is used to remove trash from the pool while using a pool vacuum.

See How to Maintain a Pool for more information on pool maintenance.

Getting Rid of Pool Algae

Algae can be prevented rather than eliminated. Algae, on the other hand, can develop in a matter of hours or even days. When dealing with algae, the best strategy is to deal with it as soon as possible.

Removing Algae

Step 1: Check the Water Levels

Test the water for chlorine, stabilizer, and the right pH with a pool water test kit to see if it’s balanced or if more chemicals are needed. Stabilizer can be used to maintain the proper level of chlorine if additional chlorine is added. Make sure it’s 7.4 to 7.6 by adding or subtracting pH increaser or decreaser.

Step 2: Clean the Pool Filter

Having algae in your pool means they’re probably in the filter as well. Backwash or hose down the cartridge depending on the sort of filter you have.

See How to Maintain a Pool for more information on backwashing.

Step 3: Brush the Pool

Brush the pool’s steps, walls, and floor with a telescoping pole and a pool brush.

Black algae must be dealt with vigorously since they are so tough to eradicate. Chemicals have a hard time penetrating the protective layers that black algae have. In order to get the chemicals to destroy the germs from the inside out, you need to break through the protective covering.

Step 4: Shock the Pool

Use calcium hypochlorite to shock the pool as directed by the manufacturer. The sanitizer may be hindered by too much acid if dichlor is used. It’s preferable to shock the pool at night or at dusk so that the chlorine liquid shock has time to kill the algae before it’s burned off by the sun.

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When handling chemicals, always use eye and hand protection.


Determine how much shock to use for your pool size by reading the manufacturer’s instructions on the product.

Step 5: Test the Water

Make sure the pH and chlorine levels in the water are correct. Shocking again in a couple of days is possible if the chlorine level is extremely low.

Step 6: Add Algaecide

Add algaecide and circulate it for at least 24 hours after shocking the pool.


To decide how much algaecide to use, follow the manufacturer’s directions.

Step 7: Brush the Pool Again

The steps, walls, and floor of the pool should all be wiped off using a broom.

Brushing is considerably more critical when dealing with black algae. To prevent fresh algae from growing in the same spot, vigorously brush the pool’s surfaces to remove all of the algae’s root systems.

Step 8: Vacuum the Pool

Remove floating leaves and debris with a skimmer and vacuum the pool to remove algae and other floating debris.

Step 9: Run the Filter

In most cases, the pool filter should be left running for at least 24 hours until the water clears. You can also use a water clarifier to aid in the removal of toxins.

Step 10: Clean the Filter

Algae can block the filter after the pool has been shocked and swept. Remove any algae that has accumulated in the filter’s grooves by rinsing it off. Alternately, if necessary, replace the filter.

How to Treat Green Algae

The most prevalent sort of algae in your swimming pool is green algae. A free-floating cloud of this species of algae darkens the water’s clarity and gives it a greenish cast. The pool bottom and walls are extremely slippery because of the green algae. Treatment and prevention of green algae are the simplest tasks.

To get rid of green algae in your pool, follow these instructions:

  • Check your pool water for chlorine, stabilizer, and pH levels using a water test kit.
  • Shock the pool with a chlorine booster to get rid of any lingering chlorine. Make sure to read the label carefully.
  • Make use of a pool brush to thoroughly clean the walls, flooring, and steps of your swimming pool.
  • Follow the manufacturer’s instructions when using a green algaecide.
  • Afterward, re-brush the pool’s surfaces after allowing the water to circulate for at least 24 hours.
  • Remove any residual dead algae with a vacuum or backwash.

Check the water levels after you’ve finished these steps to make sure they’re in the proper range:

  • Chlorine (1–4 ppm) in free form
  • (7.2 to 7.6) pH
  • Acidity (80–150)
  • Calculating the degree of difficulty in working with caustic materials

How to Treat Mustard Algae

Green algae is more common, while mustard algae is yellow in color. The removal process is also made more complicated. A common sign of mustard algae is the appearance of yellowish-brown or dirt-colored stains on the pool bottom and walls. Although it is very simple to remove mustard algae from the pool’s surface with a brush, it can quickly reappear.

Due to its ability to stick to any object that enters the pool, mustard algae makes it extremely tough to remove. Toys and swimsuits should be thoroughly cleaned after the algae has been removed from the water. Follow these steps to get rid of pool mustard algae:

  • Use a test kit to check and balance the chemical levels in your pool.
  • Add a quality pool shock product as per the label’s instructions to boost any remaining chlorine.
  • Using a pool brush, vigorously scrub the algae-infested areas.
  • Remove the dead algae by vacuuming or backwashing the pool.
  • Using the label’s instructions, apply a mustard algaecide.
  • Allow the water to circulate for 24 hours before draining.
  • Remove the remaining dead algae by using a pool vacuum or by backwashing the pool. Brush the pool and reapply algaecide every two to four days if the problem persists.

Retest and rebalance your pool’s chemistry after treatment. The optimal temperature ranges are as follows:

  • Chlorine (1–4 ppm) in free form
  • (7.2 to 7.6) pH
  • Alkalinity ranges from 80 to 150.
  • Calculating the degree of difficulty in working with caustic materials

How to Treat Black Algae

The organism known as black algae is tenacious. Its outer layer grows roots into the surfaces it adheres to, forming a protective barrier. These characteristics make it extremely difficult to remove. Spots of black algae can be seen on the pool’s surface. Aggressive treatment is necessary, as is a lot of scrubbing. To get rid of green algae in your pool, follow these instructions:

  • Use a pool test kit to confirm that your pool chemicals and pH levels are in harmony.
  • To help boost any lingering chlorine, follow the instructions on the label of a pool shock product.
  • Black algae can be scrubbed away with pumice stones or a stiff-bristled brush to remove the algae’s outer layer.
  • Strenuously scrape all of the black algae-affected regions using a pool brush.
  • Remove the algae by vacuuming.
  • Using the label’s instructions, apply a black algae treatment.
  • For the next 24 hours, let the water flow freely.
  • Vacuum or backwash away any remaining dead algae. Steps 3 through 7 should be repeated two to four more days if the algae continues.

Finally, run a final water test to check that all levels are within acceptable ranges:

  • Chlorine (1–4 ppm) in free form
  • (7.2 to 7.6) PH
  • Acidity (80 -150)
  • Calculating the degree of difficulty in working with caustic materials

Pool Algae Control & Prevention

Many factors contribute to the growth of algae in swimming pools. Poor water circulation, inadequate pool filtration, and irregular chlorine levels may be to cause. Maintaining the health of your swimming pool by preventing the growth of algae is an important part of keeping it open all season long.

  • The key to an algae-free pool is regular maintenance. Here are some tips to help you prevent algae from flourishing again.
  • Regular pool cleaning is essential for keeping the water clear of algae. Here are a few pointers to keep the algae at bay in the future.
  • Your water should be adequately circulated by your filtration system every week.
  • Algae can develop up on the pool surfaces if they aren’t cleaned regularly.
  • To remove impurities and clean hazy water, shock your pool on a weekly basis.
  • Add an algaecide to your pool every week after you shock it to avoid the growth of algae. Aside from destroying algae, algaecides can also prevent it from growing in the first place.
  • Clean all toys and swimsuits that have been exposed to natural water sources before entering the pool.

Now that you know how to get rid of algae in the pool, you’ll be able to help prevent it with ease—and treat it when necessary. The sooner you tackle the algae problem, the easier it is to get rid of green algae, black algae and mustard algae. The Home Depot delivers online orders when and where you need them. Shop pool chemicals, accessories and algaecides, and have them delivered as soon as the same day.

What’s the difference between black and green algae?

Algae in the pool may now be prevented and treated with ease—and you’ll have the knowledge needed to do it. Green algae, black algae, and mustard algae can be more easily removed if you attack the problem as soon as possible. It’s easy to get what you need at the Home Depot when you order online. The same-day delivery option is available for pool chemicals, equipment, and algaecides, all of which can be ordered online.

Gloeocapsa magma, a species of black algae, is most likely to blame for any dark streaks you notice on your roof, siding, or other exterior surfaces of your home. An organism known as Gloeocapsa magma has the ability to withstand freezing temperatures, strong winds and even the sun’s wrath.

There are two reasons for this: its black color and hard outer capsule. Gloeocapsa magma’s black pigment allows it to survive in conditions where green algae cannot.

It’s easy for black algae to grow outdoors, even in sunny spots, as long as there’s enough moisture. This dark growth is difficult to remove because it sticks so tenaciously to surfaces.

Your roof may appear to have black or gray streaks running down it because of algae.

Most likely, cholophyta algae (“green algae”) or cyanobacteriums related to gloeocapsa magmas are to blame for any green stains you find on your deck or siding. Chlorophyll, the same chemical that makes plants green, is the source of the green hue.

It is possible to find green algae anyplace there is moisture and some shade. It grows best on north-facing walls, which have a lot of water but little direct sunlight.

Algae that is green in color turns anything it comes into contact with a vivid shade of green and can be unsafe to tread on. Green algae may wreak havoc if left unchecked.

***Wet & Forget should only be used on water features without fish.

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Does algae damage surfaces?

Slippery decks and walkways can be caused by the growth of algae. You, your loved ones, and any visitors may be at risk as a result of this.

As well as looking bad, algae on your roof can wear down your roof’s shingles over time. Your roof will become less reflective and absorb more sunlight as the algae grows.

Your roof can absorb more heat if it is exposed to too much sunshine. As a result, cooling expenses will almost certainly rise.

Lichen, an invasive growth that could seriously harm outdoor surfaces, will occur if algae and fungus form a relationship.

Find out how to get rid of lichen on your outdoor surfaces by reading this article..

Application Tips

Apply Wet & Forget on a cool, overcast day for best results to avoid rapid product evaporation. Temperatures should be between 32°F and 80°F while applying the Wet & Forget Concentrate or Wet & Forget Ready-To-Use and for the next 4 to 5 hours while the product dries.

Use Wet & Forget Xtreme ReachTM Hose End with temperatures between 55°F and 80°F while applying the product and drying it afterwards. Spraying algae on a cloudy day will help keep the product from evaporating too quickly.

The product has more time to accomplish its job because the surface remains wet in cooler conditions. It is critical that the Wet & Forget has adequate time to operate on the surface to eliminate the algae efficiently.

Because of the strong outer sheath of black algae, it may take longer to entirely disappear than green algae. After 1-2 months of using Wet & Forget on black algae, effects should be visible.

Wet & Forget works best when applied to green algae, and you should see results within a few weeks. Using Wet & Forget’s method of progressive application, the work is completed.

You can use Wet & Forget to maintain the cleanliness of your outdoor surfaces once the surface is free of algae. Keep applying the cream every year or whenever new growth appears on the surface.

Don’t waste any more time trying to remove algae from your home! When you let Wet & Forget Outdoor Cleaner take care of the dirty labor, you can focus on the things you really like.

Click here to learn more about algae and how Wet & Forget Outdoor can help you get rid of it from your outdoor surfaces.

You may order Wet & Forget online right now, or you can look for it in a store near you by clicking here.