How To Get Rid Of Algae In Your Swimming Pool


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Algae in your swimming pool can be the most aggravating part of owning one. We often get the question "how do I get rid of algae". First you have to find the source. Algae can enter your swimming pool through wind, rain, or people entering your swimming pool. Combined with poor circulation, the algae can thrive and grow in your swimming pool. At this point though you probably are not worried about how the algae got there, but rather how to get rid of pool algae.

Step by Step


Step 1

Identify the type of algae- There are several types of algae that can grow in your swimming pool. Proper treatment depends on what type of algae is growing in your swimming pool. Green algae is the most common form of algae found in swimming pools. This type of algae can be found floating in the swimming pool, but can also be found on the walls. Your pool will become less clear and will have a green color to it. The wall green algae can grow in sheets and be slimy.

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Step 2

Yellow/mustard algae is a wall algae. Mustard algae, is often found in shady parts of the swimming pool. It is a hard algae to fight as it often comes back. If this is the type of algae that is in your swimming pool, it needs to be dealt with as soon as possible.

Step 3

By far the hardest type of algae to deal with is black algae. It comes in dark black, green or blue spots. It is a tar like deposit and the spots are tiny, usually no larger than a dime. Once black algae finds a way into your swimming pool, it is very difficult to get rid of. What makes it difficult are the roots. They can extend into plaster or grout and need to be taken out or it will come back.

Step 4

The last type of algae is called pink algae. Pink algae is more of a fungus and is typically found in cracks, corners, and crevices in the pool. It is usually in one area and appears as small pink spots.

Step 5

Circulation- Turn your pump and filter on to run for 24 hours per day. It is important that while you are running your pump you continuously you are backwashing your filter as needed.

Step 6

Brushing the walls- Using a Nylon Swimming Pool Brush brush down the pool walls to get as much algae off of the walls. This will help when you add chemicals into the swimming pool. If you have a concrete pool use a steel brush, if you have a vinyl pool use the Nylon Swimming Pool Brush.

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Step 7

Water chemistry- Using test strips, check your pH levels. It should be between 7.2 - 7.6, alkalinity between 80 - 120 ppm, and calcium hardness between 200 -400 ppm to ensure that your chemicals will work properly when added to the swimming pool.

Click Here to View 5-Way Water Test Strip (CL, BR, pH, Acid & Alk)

Click Here to View Pool Chemicals - (Chlorine, Balancers, Clarifiers)

Step 8

Shock your pool- Add a chlorine-based shock as needed. You will usually need 1 pound per 10,000 gallons of pool water (no algae problem). Since an algae problem is present, you will need 2 pounds per 10,000 gallons.

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Step 9

Allow the filter to do it's job- Check in 12 to 24 hours to see if your pool has made any change for the better. If it has not add a second dose of shock at a rate of 1 pound per 10,000 gallons. Repeat until the water condition improves.

Step 10

Vacuum the pool to waste- If you have to use your filter to vacuum, make certain that the filter valve is set to waste (sand or d.e. filters only). This will bypass the filter and force what you are vacuuming directly out of the pool. It is very important that you get as much as the algae out of the pool so they do not start forming again.

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Step 11

Algaecide- Use the proper algaecide to maintain your swimming pool and keep the algae at bay.

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InyoPools Product Specialist  Posted: 8/14/2017 

feathers50 - A vast majority of pool owners have used these products without problems. In extreme cases, like chlorine lock, you might have to stay away from products that increase cya or you could make your situation worse. I haven't heard of any product changing chlorine to bromine.

 Posted: 8/9/2017 

I was told not to use powdered shock because it raises cya to much and the only way to get rid of it is by draining the pool. Also not to use algaecide because it adds copper and not to use yellow treat becasue it changes chlorine to bromine. Are any of these things true?

InyoPools Product Specialist  Posted: 6/20/2017 

Old Dad - I'd scrub the bad sections with bleach, wet down the rest with bleach, then power wash it. Make sure you clean out the filter too. Wear protective gear.

 Posted: 6/19/2017 

My mustard algae in my Gunite pool was so bad I have drained it what is the best way after draining to make sure it is all gone bleach? With pressure wash ?

InyoPools Product Specialist  Posted: 6/4/2017 

Steve - Try diluted chlorine. Start with 19 to 1. Wear gloves and don't leave it on the liner too long. It can fade the colors.

 Posted: 6/2/2017 

i'm trying to clean my pool liner after the winter is there something that will clean up the algae as it is pretty grond in

InyoPools Product Specialist  Posted: 7/31/2016 

bobj - You may not have added enough shock to your pool. You want to get the chlorine level in the 10 to 15 ppm range. If you see no change, add another heavy dose of shock every 24 hours until you see an improvement. Keep your pump running continuously, brush the pool every day and clean or backwash your filter every day. Make sure the rest of your chemicals are balanced.

Anonymous  Posted: 4/20/2019 

How many minutes would you backwash it everyday?

InyoPools Product Specialist  Posted: 4/23/2019 

There isn't a set amount of time to backwash each day. You backwash each time the filter rises 10psi above the clean starting pressure. You'd run it on backwash until the water in the sight glass is clear. This usually takes a couple of minutes.

 Posted: 7/29/2016 

I took your advise & added 3 pounds of shock & after 12 hrs no improvement. When I checked chlorine reading, the color in tibe was red. What should I do now?

Anonymous  Posted: 8/10/2015 

I have been dealing with mustard algae in my 16'x 48" pool all season. It is so fine that when I vacuumed, it went right through the filter and back into the pool. After a couple of attempts at super shocking and algae killer, I decided to try something else. I took the ladder out of the pool and placed it next to the pump. Then I removed the hose from the fitting going into the pool and taped the hose to the top rung of the ladder. This assures that all of it goes on the ground and not back in the pool. Then I vacuumed it up and "presto" a clean pool again. The first time you do it you may have to do it again in two days but every time you do it, it takes longer for the algae to spread. I do it about every 5 days. It sounds like a pain but 15 min. every 5 days is nothing for a clear, sparkling pool. I learned my lesson and will make sure my liner is clean next year.

InyoPools Product Specialist  Posted: 7/17/2013 

algaecide - Assuming that your pool chemicals are balanced, you should see results of adding algaecide in 24 hours.

Anonymous  Posted: 7/16/2013 

How long after you put in algaecide should you see results?

 Posted: 7/3/2013 

Until today I did not know about back washing to aware. I wish I had know when first opened the pool this summer, having problems with cloudy water , but following all your suggestions, which are great, i now know how to deal with it, thanks AJ