How To Get Rid Of Green Pool Water

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It's never fun to pull back your pool cover and see that the water has turned green and swampy. That means algae has temporarily taken over, and you'll need to thoroughly clean and treat your pool before you can start swimming. Read on to learn how to get rid of the dreaded green water.

1
Test your swimming pool water. Use a chemical test kit to test the chlorine and pH levels and determine the extent of the problem. When chlorine levels drop below 1 ppm, it can cause algae to grow in the pool, turning the pool water green. When this happens it is necessary to "shock" the water with chemicals to kill the algae and return the pool to normal chlorine levels.^[1]
- Proper pool maintenance, including having working filters and making sure your pool's chlorine and pH levels remain steady, can prevent algae from growing in the first place.
- Algae is constantly growing, so letting your pool sit without maintenance for even a few extra days might create a green pool water situation.
2
Balance the pool chemistry . Before treating the pool, balance the pH by adding either an acid or a base to bring the level to just around 7.8. This is at the high end of the range you would normally want in your pool, but that's necessary when you're treating it for algae. Here's how to balance the pH:^[2]
- Turn on your pump so the chemicals will circulate throughout the pool.
- Correct the pH level by either increasing the pH with sodium carbonate or decreasing it with sodium bisulfate.
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3

Make sure the filter is working properly. Clean out any leaves, sticks, and other debris that may be clogging the filter. Backwash the filter if necessary and make sure it is working well before you add chemicals to the pool to kill the algae. Set the filter to run 24 hours per day so it filters out all the algae during the cleaning process.
4
Scrub the sides and bottom of your swimming pool. Use your pool brush to scrub the pool well before adding any chemicals to the water. Algae clings to pool surfaces, but scrubbing will remove it. Scrubbing also helps to break the algae up, allowing chemicals to work faster.^[3]
- Scrub especially well in areas where you can see algae buildup. Try to break it all up so that the pool gets thoroughly clean.
- If you have a vinyl pool, use a nylon scrub brush. Wire brushes might damage vinyl pools, but may be used on plaster pools safely.
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1
Treat the pool with pool shock. Pool shock has high levels of chlorine that wipe out the algae and sanitize the pool. Choose a powerful shock with around 70% available chlorine, which is enough to handle tough algae and bacteria. Follow the directions on the shock package to make sure you use the proper amount for the water in your pool.^[4]
- If you have a high amount of algae in your pool, you may have to treat it more than once to keep the algae from continuing to bloom.
- The water might look cloudy or dirty when you add the shock, but as the water runs through the filter it will begin to clean up.
2

Treat the pool with algaecide when chlorine has fallen below 5. 0. Allow the algaecide to work in your swimming pool for at least a 24-hour period.^[5]
3

Prevent pressure buildup in your filter by cleaning it often to remove the dead algae. When algae dies, it will fall to the pool floor or float in the pool water. It will also lose its green color.

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1

Vacuum up the dead algae left behind in your swimming pool. Use your brush to clean the bottom and sides of the pool again, then vacuum up all the dead algae. If there are a lot of dead particles and you're having trouble vacuuming them, you can add a flocculent to help the algae bind together and make it easier to vacuum.^[6]
2

Run the filter until the algae is gone. Your swimming pool water should be crystal clear after treatment. If the algae seems to be coming back, go through the shocking and treating process again until it's all cleared away.
3

Re-check chemical levels with your swimming pool test kit. All chemical levels should be in the normal range.

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Question

I just filled my pool up and put my chlorine tablet in my filter. My pool water is a clear green color. What did I do wrong and how can I fix it?

There's nothing you have done wrong. I would suggest keeping your filter running 24 hours a day so that your water is continuously circulating and your filter is always catching debris. The green color in the water means that there is algae present, and the only thing that will get rid of algae is a sanitizer (chlorine). Sometimes just putting one chlorine tablet just isn't enough chlorine. This means you have to find a way to put in large amounts at once, which is referred to as "shocking" your water. I usually use liquid chlorine to sanitize my water, and then I add two tablets in a floating chlorinator so that I always have chlorine entering the pool.
Question

My pool has turned green and has sand in it. How do I clean it without draining it?

Run your pool filter, then scrub your tile surfaces. Vacuum and shock your pool afterwards. If sand and debris are still present do a backwash.
Question

How do I get rid of dirt in my pool, since I don't want to use a net every five minutes?

Add a Polaris to the system that will do the job for you. It will require an additional pump in most cases, but you can have it run for a shorter period so that it just cleans the pool once a day.
Question

How do I clean a green pool and swim in it?

Depending on the size of your pool, add liquid chlorine and leave the pump running for 24 hours. Do a check and take a sample to your pool shop. You can add 5 litres of liquid chlorine to a 35,000-litre pool and still swim without your hair going green, but you may need to add a buffer and stabiliser.
Question

I have an above ground pool, and I am having a hard time getting the algae out. I have not changed the sand in some time. Do I get the algae under control or change sand first?

Take care of the algae first and backwash several times. Backwashing will help clean the algae out of the sand filter. Once the algae is gone, then it's safe to change out the sand. There's no point in replacing the sand and then contaminating it with algae.
Question

How much bleach do I put in a 4,000 gallon pool?

One gallon of liquid chlorine per 10,000 gallons is a healthy shock, so if you are looking to shock and hit it appropriately, go with 1/2 gallon of liquid chlorine.
Question

Can I overshock a pool with algae? I have tried bleach, shock and muratic acid, but the pool is still green.

The reason your pool is still green is most likely because of metals in the water. When you shocked the water and it stayed green, you oxidized the metals in the water. What you need to do is add some ascorbic acid to the water. Then place some sequestering agent in the water and, finally, a metal eliminator (try CuLator Metal Eliminator).
Question

How often should I change sand on a filter above ground?

It is the same as below ground. Every 3-5 years, but if you are handy you can open the filter and clean the sand.
Question

How often should I change the sand in a sand filter for a saltwater pool?

For an above ground pool that is saltwater, the filter sand is supposed to be changed every three to four years.
Question

My water is clear but my pool is still green. I've shocked it, but my filter and vacuum are clean. What can I do?

Do you mean the pool surface is green? If it is, then you must continually scrub it until all surfaces are clean, and then keep the pool at shock level until your pool passes three tests: (1) pool and all surfaces are clean and clear; (2) cc's less than .5 ppm; and (3) you pass what is called an overnight chlorine loss test. In other words, you do not lose FC while the sun is down, meaning their is no organic matter breaking down your chlorine.

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Use your pool net daily to remove leaves and other floating matter from the top of the pool. It's much easier to remove debris before it settles on the bottom.
Wear old clothes when using pool chemicals. If chlorine spills or drips on clothing, it may remove some color.
You can take a water sample to your local pool store on a monthly basis and get a computer analysis. This can help you catch pool water problems early.
Keep your chlorine level between 2.0 and 4.0 ppm to prevent algae from developing in your swimming pool.^[7]

Thanks for submitting a tip for review!

Do not add any chemicals to your pool unless you know what you are doing. Adding the wrong chemicals will create additional problems.
Use extreme caution when exposed to chlorine. It may cause a sore throat, a cough, or skin, eye and lung irritation.
When mixing pool chemicals with water, use caution. Always add the chemical to the water.
Never mix chemicals together.

Things You'll Need

Chemical test kit
Pool brush
Chlorine shock
Algaecide
Pool vacuum
Pool net

About This Article

Article SummaryX

To get rid of green water from a pool, start by using a chemical test kit to test the chlorine and pH levels. Then, add sodium bicarbonate to increase the pH, or sodium bisulfate to decrease it. Next, clear any floating debris, and scrub the sides and bottom of the pool with a pool brush. Afterwards, add a pool shock with 70% available chlorine, or an algaecide if the chlorine level has fallen below 5.0. Let the treatment sit for at least 24 hours, then use a pool vacuum to remove the dead algae. For more advice, including how to prevent green water by cleaning and maintaining your pool filter, keep reading.

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