How to Clean a Green Swimming Pool (Algae)


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Has your pool turned green? There are ways to take on a green swimming pool. Turning your pool from green back to crystal clear will take some time. With a little patience and work your green swimming pool will be ready to swim in again.


Step by Step


Step 1

Run the pump and filter for 24 hours - Running your filter will help filter out tiny particles that are also to blame for your green swimming pool. Due to the fact that your pool will be running 24 hour, your filter will become clogged quickly. You will need to backwash your sand or d.e. filter whenever the pressure increases 8-10 psi above the normal reading. For example, if my pool normally reads 12 psi (when it's clean), I would backwash when the gauge reaches 20-22 psi.

Step 2

Remove any large debris and leaves - Using an aluminum leaf rake or leaf bagger attached to a telescopic pole, remove the larger debris found on the bottom of your swimming pool. The large debris needs to be taken out first to ensure that you will not clog your pool cleaner, skimmer, main drain, filter, or piping.

Step 3

Balance your chemical levels- A balanced water chemistry is essential if you want to get the pool clear.

CLICK HERE FOR MORE ON ADJUSTING CHEMICALS How To Maintain A Swimming Pool Part 3 (Adjusting Chemicals)

Step 4

Brush down the surface of the pool- Have you ever touched algae? Algae usually has a slimy coat. That slimy coat protects it. Brushing helps remove that protective coat and expose it to the chemicals in the water. Brushing down the walls will help remove some of the algae that is growing on its surface. Any algae that remains will be killed when the pool is shocked.

Step 5

Shock the swimming pool - Using pool shock will kill off bacteria and algae that is still in your green swimming pool. Most likely if your pool is a deep green you will need to add several bags of pool shock over a period of days. This step should start to clear up your swimming pool.

Step 6

Algaecide - An algaecide will help treat and prevent the return of algae. An algaecide should be part of the weekly maintenance. This step is optional, but highly recommended.

Step 7

Remove any remaining debris - Using a leaf rake, leaf skimmer or an automatic pool cleaner, remove any remaining debris left in your swimming pool. The clarity in your swimming pool should have improved drastically by now. If not, repeat steps 5 and 6.

Step 8

Your swimming pool should be crystal clear once again. A little weekly maintenance (water testing, adjusting chemicals) will help prevent the swimming pool from turning green again in the future.


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 Posted: 5/10/2019 

I've seen some videos where the filter is set to recirculate for the 1st 24 hours after brushing and shocking. Seems like a good idea to me because after stirring up the algae and then killing it with chlorine much of it falls to the bottom where it can then be vacuumed to waist.

InyoPools Product Specialist  Posted: 6/26/2017 

memaw - Bleach is the same as chlorine only weaker. The internet has instructions on how much bleach to add instead of liquid chlorine.

 Posted: 6/24/2017 

I am confused on when to use shock or when to use bleach

InyoPools Product Specialist  Posted: 5/18/2016 

Lainey - Actually, these steps are out of sequence. I would pull out as much of the large debris before you run the filtering system to keep it from clogging the filter.

 Posted: 5/17/2016 

Can step 2 be done while you're running the filter for 24 hrs (Step 1), or are you supposed to wait until after the 24 hrs so the larger debris doesn't get stirred up?

 Posted: 10/12/2015 

very easy to follow, very helpful and useful, very organize, Thank

InyoPools Product Specialist  Posted: 6/12/2015 

gpage - See our guide on "How To Break Chlorine Lock". It has information on what chlorine lock is and how to break it.

 Posted: 6/11/2015 

I have been struggling with my green pool for over a week. 24 ft above ground. My chlorine level has been high this week but the green is still there. A local pool place thought it was chlorine block and 24hrs ago I put in 6 backs of shock and later in the day 6 gallons of bleach. When I backwash it comes out green/brown so it is filtering, but I am at a loss.

 Posted: 6/10/2015 

Great article with detail information was very helpful.



InyoPools Product Specialist  Posted: 6/18/2014 

SKJ - Make sure all of your pool chemicals are balanced before you shock you pool, especially the pH. After shocking, use an Algaecide.

 Posted: 6/17/2014 

I opened my pool after the winter is over and found it dark green. For the past one week I have been shocking the pool with little clarity. What do I do to clear it up.

InyoPools Product Specialist  Posted: 7/15/2013 

leaking light - If you have a line across the lens, it sounds like you may have had water in the light fixture at one time. Maybe the previous owner corrected the problem and just didn't clean the lens. I would take the light fixture out of the niche and look at it just to be sure there is no water in the fixture now. See our guide on "How to Replace a Pool Light Bulb" for more information. As long as you have it out, I would replace the gasket to avoid future problems.

Anonymous  Posted: 7/12/2013 

I followed these steps, pool looks amazing but I noticed algae on the inside of the glass lens in the top 1/3, visible at night when the light is turned on. Does it sound like there is there a leakage problem in the light fixture? No one has swam in the in-ground pool at night since we recently moved in and I am concerned about electric/water danger issues - please advise.