Today you're going to learn how to FINALLY get rid of your pool algae (and keep it that way).
The steps and processes laid out in this guide will keep you better educated around pool algae and what you can do about your algae problem.
Dive in to learn all about what pool algae is, why it grows in your pool in the first place, how to prevent algae from growing in the first place, and (finally) how to kill algae.
Let's get to it!
How to get rid of algae in your pool in 13 steps
Sometimes despite our best efforts to prevent them, those sneaky little spores find a way in and start to grow.
Maybe you just didn’t have time to maintain your swimming pool the way you meant to or maybe your filter got clogged without you noticing.
Either way, you have a problem and now you just need to know how to fix it.
Removing algae may not be rocket science, but it does require a bit of biology.
It will certainly take some time and a little hard work, but with the proper steps and equipment, you’ll be an algae-killing expert in no time.
If you follow these steps to the letter, you'll most likely be able to remove all the algae growth from your pool, but if you find some lurking behind, repeat the steps until it’s clean.
Are you ready to get to work? Great! Let’s get started.
1. Test & balance the water chemistry
In prevention and treatment, water chemistry is one of the most important steps to getting and keeping your pool algae-free.
You need to test your chlorine and pH levels with a good test kit (which are more accurate than test strips), and bring your pH level to about 7.8 by adding sodium carbonate to increase it or sodium bisulfate will also need to make sure the chlorine is at least above 1 ppm.
2. Turn on the pump
While treating your pool, your pump will need to be running 24 hours a day.
This keeps the water from stagnating and helping the algae to grow again.
3. Remove debris
- Super-strong, structural molded leaf rake
- Deep fine-mesh bag handles both big clean-ups and small debris
Remove as much floating debris as you can with a net, including floating algae and leaves.
You can use your hands, a net or your kids. Whatever gets the job done!
4. Brush your pool
- STRONG: Metal backing provides enough strength to thoroughly clean pool walls
- FLEXIBLE: Designed with poly bristles to help reach the toughest corners
The type of brush you use for this will depend on the type of pool surface you have.
If you have a concrete or plaster pool, you should use a wire or stiff pool brush. Scrub down all the surfaces of your swimming pool well, including steps, corners, pool wall, and under ladders.
5. Vacuum your pool
Vacuum your pool surface as thoroughly as you can to remove any algae or debris loosened while brushing, again making sure to clean under stairs, along the pool wall, and on steps.
While I love a good robotic pool cleaner, it's not the best for cleaning algae, so you're better off doing it manually.
6. Clean your filters
Your pool’s filter system will be an essential part of removing dead algae, so clean them out, rinse them off and make sure to backwash sand filters or D.E. filters. (You can clean your cartridge filter).
To backwash a filter, you will:
7. Shock your pool
- Powerful chlorine shock treatment that is great for regular maintenance
- Quickly eliminates algae, bacteria, and other harmful contaminants from your pool water
Now it's time to shock your pool with a good calcium hypochlorite shock.
Yes, you're supposed to be shocking your pool weekly anyway, but getting rid of an algae overgrowth may require a little extra treatment, especially if it’s been neglected for a bit.
Pool shock is basically super-chlorinating your pool to kill off anything that shouldn’t be living there. How much you have to use will depend a lot on the type of algae you have.
Black algae usually requires shocking multiple times to get it clean and keep it from returning.
Make sure to wear gloves and clothes you don’t mind getting bleached in case you get it on you. If you choose powdered shock, first add the shock to a large bucket of water and stir it in.
Follow the manufacturer’s directions for how much to use for your swimming pool, then pour the shock mixture all around. Liquid shock can be poured directly into your pool without mixing it with water.
It’s best to shock while the sun isn’t out so that your pool’s chemistry is not affected by environmental factors.
The water might look cloudy after this treatment, but your pool’s filter should clear it up in a day or two.
>>Read: How to clear a cloudy pool
Just make sure you don’t allow anyone to enter the pool until the water is completely clear and the chlorine tests at less than 3 ppm.
And don't use stabilized chlorine (cyanuric acid) for this job, which can block the sanitizer from working.
8. Brush your pool again
Don’t skip this step. It will help in the next steps to completely remove algae blooms from the pool.
9. Floc your pool
A pool flocculent will further remove any small spores or particles that weren’t eradicated in the shocking process.
This is an especially important process if your pool is infested with hard-to-get-rid-of algae like black or mustard.
Vacuum the bottom and sides of the pool well to help get the algae out.
11. Clean your filters again
After this process, you will likely find more algae blooms and debris in your filters.
Clean them out and backwash if necessary to keep it from recirculating into the water.
12. Add algaecide
A good algaecide is crucial to removing algae and helping to prevent future outbreaks.
13. Test your pool chemistry
Finally, it’s time to restore your pool’s chemistry back to normal.
Normal chlorine levels are ideally between 1 – 3 ppm, and normal pH levels are between 7.4 and 7.6. 7.5 and is considered perfect for algae prevention.
And alkalinity should be between 80 and 140 ppm.
6 tips to preventing algae
“An ounce of prevention is worth a pound of cure,” or so they say, and that couldn’t be truer than it is with algae.
If you can stay ahead of the problem and keep it from overtaking your pool, you will save yourself hours and hours of unnecessary headache.
But how do you prevent a seemingly unavoidable nuisance?
Well, it’s not easy, because it’s true that algae finds its way in, sometimes despite all your best efforts.
However, if you take the precautions we lay out here, you will be miles ahead of the game and able to eradicate algae before it moves in with its whole family.
1. Take care of your pump
Algae likes to grow in stagnant water, so you need to make sure your swimming pool’s water is always circulating.
Clogged or under-performing pumps will create an optimum environment for algae to get comfortable.
At least twice a week, you should check and clean your skimmers and pump strainers.
>>Read: How to troubleshoot your pool pump
It’s a good idea to give them a good rinse-off outside the pool to wash away any spores that are too small to see.
Sand or D.E. filters need to be backwashed regularly, and there are some cleaning solutions made just for this purpose for a little extra cleaning power.
Always run your pump around 10 hours a day during heavy swim season to keep the water moving.
2. Shock your pool
Once a week, you should go through the process of shocking your pool with a good pool shock.
This is a process of power chlorinating the water to get rid of any bacteria and spores that may be resisting your regular chemicals.
3. Brush your pool
Just like with brushing your teeth, it’s important to maintain a regular brushing schedule for your pool.
And make sure you are using the correct brush for your pool’s surface.
A vinyl or fiberglass pool is a little more susceptible to damage so you will need a good nylon brush that is made not to scratch those surfaces.
A concrete pool or plaster pool that are stronger can be brushed with wire brushes for maximum effect.
Since these materials are more porous than vinyl, algae tends to take root on them much easier so a tougher scouring method is helpful.
4. Check your pool's chemistry
Many new pool-owners don’t realize how quickly algae can take over until it’s overtaken and requiring major cleaning.
Your pool’s chlorine level should stay between 2.0 and 4.0 ppm (parts per million) to keep bacteria and algae to a minimum.
Algae spores will obviously still enter your pool from time to time, but a healthy level of chlorine will kill them off before they have a chance to bloom.
Likewise, checking and regulating your pool’s pH levels will help keep spores from blooming.
Algae thrives in a high pH level. The guideline for a pool’s level is between 7.2 and 7.6, 7.4 being ideal.
This is the same pH level in mucous membranes and human eyes, also making it a safe environment for humans.
5. Vacuum your pool
Just like your carpets, vacuuming weekly will eliminate smaller particles of dirt, debris and algae you might not even see yet.
>>Read: How to vacuum your pool
It’s best to vacuum your pool’s surfaces after brushing to remove loose particles removed during that process.
6. Use a good algaecide
Since algaecides are made specifically for keeping algae at bay, regular use of it in your pool will keep it clean and clear.
There are specific algaecides available for the various types of algae for times when there is already a growth and you know what type of infestation you are facing.
But multi-purpose algaecides will help prevent them before they are a problem.
What is algae?
According to study.com, “algae is the name given to a large and diverse group of oxygenic, phototrophic, eukaryotic microorganisms. Algae are eukaryotic, which means they have a nucleus.”
Or more simply put, a slimy plant-like organism that produces oxygen through photosynthesis (totally paraphrased).
Algae comes in different forms like seaweed and pond scum. In other words, like other plants, it's important to our existence, but there’s no reason you need to harbor it like fugitives in your swimming pool.
If you don’t house it, some other pond, pool or unsuspecting body of water will!
You might wonder why algae in the pool matters until you’ve been infested with it.
Well, it's slimy, slightly and just plain gross!
Your kids probably won’t step foot in a green pool and your investment will go to waste.
Not to mention, you can’t see what’s lurking at the bottom of the pool when it's overgrown.
Many people wait until their pools start to change colors to do anything, but the problem is that it can take over quickly.
You may think you’re in the clear if you don’t see any green color, but actually there are many different colors and types of algae.
The 7 major types are:
But there are really only a few specific types in these families that you need to worry about as a pool-owner:
Green algae is the easiest to get rid of, and can usually be treated successfully with a little extra chlorine or algaecide.
Mustard algae (or yellow algae) has beta carotene, which gives them a more yellow-like appearance.
It’s a more difficult algae to get rid of than green algae because of its chlorine resistance, and is also a little harder to detect because it can often be mistaken for sand or pollen because of its light appearance.
Getting rid of mustard algae usually requires a few extra steps like shocking and brushing.
Black algae is also called blue-green algae, but it’s actually not algae at all. It’s a bacteria called cyanobacteria and grows in large masses.
This one is the most frustrating to get rid of because it takes root in cracks and crevices, making it difficult to remove. It also has a protective layer, often called a head that makes it particularly resistant to chemicals.
To get rid of black algae is a lengthy process, sometimes even involving draining the pool and acid washing the pool surface.
Pink algae is another form of bacteria and it appears in cracks and corners and spreads quickly.
It is also chlorine resistant, but can be treated with large amounts.
Getting rid of pink algae is not quite as intensive as getting rid of the black kind, but it will usually require shocking and brushing, sometimes repeatedly.
Why is algae bad for my pool?
So, why is it bad for your pool?
Well, besides being an eyesore, it can wreak all kinds of havoc on your summer fun in a few specific ways:
1. Erosion & staining
Keeping your pool water balanced is important for many reasons, but for your pool surfaces, it’s essential.
Algae can raise your pool’s pH level, causing scaling and calcium deposit buildup.
These things will erode both concrete and fiberglass surfaces over time, and coupled with elements like dirt, skin particles and algae can cause discoloration and staining.
2. Clogged filters
Algae has a tendency to clump together and reproduce, making it extremely difficult for your pool filter to do its job.
The black kind in particular has a sticky surface and takes root in crevices and openings. It clings to the mesh and openings in filters, hanging on to other spores and debris until it forms clogs impossible to filter out normally.
Clogged filters create poor circulation in the pool, worsening the problem of breeding algae.
While algae itself is not harmful to humans or pets, it can trap bacteria within it like E. coli, circulating the harmful germs in the pool water.
4. Slippery steps
Algae is slimy and slippery, so when it starts to grow on ladders, on the pool wall, and steps, it can make for some slick areas around the pool.
Why & how does algae grow in my pool?
Algae spores are constantly making their way into your pool either through environmental elements like wind and rain, through swimsuits, or objects that were recently in the ocean and through people dragging them in.
Once the spores reach the water, ideal environments then cause them to bloom and reproduce.
Several factors, some unavoidable, contribute to the overgrowth of algae:
Enjoy your pool!
Depending on the type and amount of algae you have invading your pool, the tasks in these steps may go by quickly.
You also may find it unnecessary to vacuum your pool twice if you only have a small amount that you feel you’ve successfully removed.
However, if you have an overgrowth or a black algae infestation, you may have to shock as many as four times, which will require that you repeat most of these steps.
I know that getting rid of algae can be a huge hassle. That’s why it's always a good idea to maintain your pool and clean it regularly.
Now, go have a swim. You earned it!