How to Get Rid of Algae in Your Pool


Very few things can be more frustrating than finding your cherished swimming pool infested with swarms of green, black, or yellow algae. Although they don’t pose any direct threat to our well-being, they can still be a health hazard as they serve as the breeding ground for different types of bacteria. Aside from that, they make our pools look disgusting and uninviting. Opening your pool properly and following good pool cleaning tips and practices are often enough to ensure that your pool is safe from algae infestations. But since you’re reading this, we’ll assume that your pool is already under attack and that you’re looking for a way to fight back. Don’t worry because we’re here to help – from knowing who your enemy is to getting rid of them and making sure that they don’t come back – we got you covered.

Pool Algae Types

The first thing you need to do is to identify what type of algae has taken over your swimming pool. Armed with this information, you will be in a better position to attack your enemy and turn the tide in your favor.

Green Algae

Green algae are the most common type of algae that attack swimming pools all over the world. They typically appear in various shades of green (from dark green to yellow-green and even blue-green) and can be seen sticking to the pool walls and floors or floating in patches on the water’s surface where there is low water circulation.

If green algae spores are left untreated, they will rapidly spread throughout your swimming pool (these growth spurts are called “algae blooms”) and overwhelm the chlorine or bromine sanitizers in it and render them useless. Also, green algae on pool walls and surfaces are known to leave ugly stains and marks if not removed immediately. Furthermore, green algae may also end up clogging your pool filters and put a strain on your pool pumps.

Black / Blue-green Algae

Black algae (which is actually more like a blue-green hue) is considered by many as the worst kind of algae that can attack any swimming pool. They can be very tough and resilient, surviving even after a thorough pool cleaning.

Black algae grow in layers, with the spore’s roots finding their way and clinging to surfaces of the pool and the outer layers creating a protective coating to protect the layers underneath. A final waxy coating lies on top which makes it impervious to normal chlorine levels.

Black algae typically grow in concrete or plaster finished pools (especially in the cracks and crevices) since the porous surfaces make it easier for the spores to take root. Besides, black algae also thrive in shaded areas of the pool like the interior of your pool skimmers for instance.

Yellow / Mustard Algae

As the name suggests, yellow algae have a yellow-orange or mustard-like color to them and can have a powdered or dusty appearance. Because of that, many pool owners often mistake them for dirt or sand in the pool thereby neglecting to clean them.

Like other types of algae, yellow or mustard algae thrive best in the shaded areas of the pool, which includes behind the ladders, underneath the pool slide, and even in the vertical faces of the pool steps that don’t get much sunlight.

Although similar inconsistency with green algae spores, yellow algae spores are much smaller and can therefore easily pass through the pool’s water filters. Because of this, they can be more challenging to remove and will come back easily unless the pool is properly cleaned and treated.

Pink Algae

Pink algae (or “pink slime”) aren’t really algae; they’re actually a form of bacteria. Many pool owners consider them as algae because they’re slimy and grows in areas of the pool that aren’t exposed to direct sunlight and have little to no water movement, just like the actual algae.

Since they’re more bacteria than algae, typical algaecides and other anti-algae treatments are useless against pink algae. To remove them from the pool, you will need to use anti-bacterial pool cleaning solutions. There are solutions made specifically for “pink slime” which should be available in your local pool supplies store.

Removing Pool Algae


Different experts will have different opinions as to what is the best method for getting rid of algae in your pool. However, the following steps should be effective in general. In fact, the procedure for cleaning green, black, or yellow algae from swimming pools are almost the same except for the amount of pool shock to be used.

1. Manually Vacuum the Pool

You may want to put aside your automatic and robotic pool cleaners since they won’t be of much help when it comes to cleaning algae in your swimming pool. Manual vacuuming is recommended because it allows you to pay close attention to areas with algae.

When vacuuming your algae infested pool, be sure to remove as many organic materials and loose debris out of the water as to make the shock more effective.

2. Scrub the Pool

Use a nylon brush attached to a telescoping pole to scrub the walls and floors of your pool. Avoid using a steel brush since this will damage your pool’s lining. When scrubbing the pool, pay particular attention to corners and shady areas since these are where algae thrive most. You’ll also notice that as you scrub along, the water will become dirty and cloudy, which will then make it hard for you to see the pool’s floor and the lower parts of the walls. That said, you should definitely start cleaning those areas first and make your way to the top. Just be sure to do this thoroughly since any missed spot is a place for the algae to continue growing.

Scrubbing is supposed to break the layers protecting the algae so that the shock can penetrate and kill the algae. Also, it helps to stir the sediment that you’ve brushed off so it can be filtered out of the pool.

3. Test and Balance the Water

Check your pool water’s alkalinity and pH levels using a pool water testing kit. If you’re not sure how to use a pool water testing kit, you can simply grab a water sample, bring it to your local pool supply store and have them test it. Based on the results, you can now work on balancing your water chemistry. This is an important step since imbalanced water chemistry (i.e. high pH levels, low alkalinity levels, etc.) may inhibit the effectiveness of the sanitizer against the algae.

4. Shock Your Pool

You’ll need more shock than what you’re normally using (which is typically about 1 lb. per 10,000 gallons of pool water) so make sure that you have enough in stock. Otherwise, you’ll just be wasting time since using an insufficient amount will not kill the algae. Remember, algae are resistant to normal levels of chlorine or sanitizers.

As mentioned earlier, this is where treatment approaches will vary for the different types of algae. If you’re dealing with green algae, you’ll need to use twice as much shock as you normally would. If it’s yellow algae, you’ll need thrice as much. And in the case of black algae, the most resilient of all, you’ll have to use four times as much shock.

The best way to add shock to your pool is by using the bucket method. All you need to do is to pour the shock into a bucket filled with a couple of gallons of water and mix. Then walk around the perimeter of the pool while pouring the shock into the pool water.

Give the shock some time to work, which can be anywhere between 12 and 24 hours. Once the shock has done its magic, your pool water, and the algae should turn into a gray or blue cloudy color and will drop to the pool’s floor or float on the water’s surface.

If after 24 hours (some pool owners like to wait for at least 48 hours) and the algae still hasn’t cleared up, you’ll have to go back to steps 1-3 and do the whole thing all over again before administering another shock treatment.

5. Filter, Filter, Filter

Once all the algae are dead, turn your filter on and keep it running for a minimum of eight hours. This should be enough time to clear the water. You may add a pool water clarifier as this can help speed up the process.

Keep in mind that your filter may clog up more frequently during this process considering the number of dead algae and other sediments in the pool water. If it does clog, you’ll need to backwash your pool to ensure that it operates efficiently.

6. Test Your Water Again

Once you see that the pool water has cleared up, you’ll want to test it again. You’ll want to make sure that your water chemistry is balanced and your chlorine level is back to normal. Again, if you’re not sure how to properly test your pool’s water chemistry, get a water sample and have your local pool supply store do the analysis.

7. Clean Your Filter

After all the cleaning, you can be sure that there are particles and spores trapped in your filters. To prevent these particles and spores from getting back into your pool water, take some time to clean your filters thoroughly. Don’t simply rinse them; do a complete and deep clean. You may also consider getting a new filter instead, just to make sure that your filters are completely free from any algae spore.

Keeping Pool Algae Out

Keeping algae from infesting your pool is actually a simple matter of maintaining clean and balanced pool water. But to further ensure that the algae stay out, then keeping the following in mind can help.

Clean Your Filters Regularly

Your pool filtration system is composed of multiple types of filters. Water pump filters, skimmer baskets, sand or DE filters – all of these filters work together to ensure that your pool water remains clean and clear. Clogged filters will hurt your pool water’s circulation, which in turn creates dirty and almost stagnant water, thus creating the perfect environment for algae growth. Also, filters can catch algae spores and send them back to the water if they’re not cleaned out.

Scrub Your Pool Regularly

Make it a point to scrub or brush your pool at least once a week. This will help to break up algae formation in its early stages and at the same time enhance the effectiveness of your water sanitizers. When scrubbing your pool, make sure that you brush the walls, floors, steps, and every other area in your pool. Pay particular attention to cracks and crevices (especially in shaded areas) since this is where most algae formations usually start.

Maintain a Chlorine Leve of 2 ppm

Regularly test your chlorine levels and try to keep them at around 2 ppm (parts-per-million). This should be enough to kill algae spores in the pool and prevent them from turning into algae blooms. When your chlorine levels drop, you’re bound to see algae growth spurts pretty soon. During the hot summer months, you’ll want to test your pool water at least once per day.

Keep Pool Water pH level Balanced

Aside from the chlorine levels, you’ll also want to check your pool water’s pH levels and keep them between 7.4 and 7.6. Keep in mind though that this by itself will not kill the spores since algae can survive in pool waters with 6.5 to 12.5 pH levels. However, keeping your pH levels balanced will enable the chlorine or any other sanitizer you use to be more effective in keeping the pool water clean and free from algae.

Avoid Fertilizing Near the Pool

You may have added a few plants near your pool to improve the aesthetics and ambiance. However, this may present a problem since the nitrogen in fertilizers is the natural food for the algae. By applying fertilizer to your plants (which will run off to the pool when it rains), you are basically feeding the algae and letting them grow. This is not to say that you can’t have plants near your pool, it’s just that you’ll have to make sure that you have a good drainage system so that the rainwater carrying the fertilizer doesn’t end up in your pool.

Globo Surf Overview

Cleaning the algae out of your pool will require hard work, patience, and some pool cleaning tips that may not be part of your regular pool cleaning routine. You’ll also need to be precise because if you miss even just one spot, you can be sure that your algae problem will be back in no time to pester you yet again. Nonetheless, all the effort and time you put into properly cleaning your pool will definitely be worth it, especially when you see your kids and your guests having a grand time swimming and splashing in your pool’s crystal clear waters.

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My name is David Hamburg. I am an avid water sports fan who enjoys paddle boarding, surfing, scuba diving, and kite surfing. Anything with a board or chance I can get in the water I love! I am such a big fan I decided to start this website to review all my favorite products and some others. Hope you enjoy!