How to Clear Green Pool Water Fast - Pool Care School (2023)

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The last thing you want to see when you go swimming is green pool water. It happens to the best of us though. A slight oversight or busy schedule, and pool maintenance gets put aside.

Before you know it, you have an unsightly and unsafe pool to swim in (please don’t). Now rather than swimming, you’re trying to learn how to clean a green pool.

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Why Is My Pool Green?

Looking at your green pool, you may scratch your head and wonder why? What makes swimming pool water green you might ask. The answer is there are many things that cause pool water to become green.

One of those reasons is algae. You know it’s a part of owning a pool, but why did it get so bad that your pool turned green? Continue reading to learn ways to fix green pool fast and safely.

The reasons algae grows or overgrows, varies. It could be due to pool owner error, chemical imbalances, or even the weather. Here are a few of the most common reasons:

  • Imbalanced pH Levels – You don’t want a pH that’s too low because it will cause irritation to anyone in the water, especially the eyes. But, if the pH is too high, it causes skin irritation, and allows bacteria and algae growth, aka green pool water.
  • Non-Working Filter – Check your pool filters often. If you don’t, they could easily clog up, which means the algae doesn’t filter out of the pool. Not only that, but you’ll have an overgrowth of bacteria, which means unsafe pool water, not to mention it’s abnormal green color.
  • Warm Weather – You want the weather to be warm for swimming, obviously, but drastic changes in the weather or humidity levels calls for more frequent and thorough cleanings as algae thrives in warm, humid temperatures.

Fortunately, there are ways to clear green pool water and not lose too much precious swimming time. Let’s check out how to clean a green pool fast.

6 Ways to Clear Green Pool Water

Pool water troubleshooting can be frustrating. Don’t worry though, when your pool water turns green and causes your swimming pools water to get disgusting we’re here to help! We’ll have your pool back to crystal clear water in no time.

Below we’ve outlined the first six things you need to do to help turn your not clear, cloudy pool into a beauty!

1. Check the Pool’s pH Levels

If the pool’s pH levels are too high, you’re more likely to have algae growth. Before you do anything, use a water test kit to test the pH levels.

You can do a full-blown testing, checking all levels, or focus on the pH level for now. If the levels are too high, use your favorite method to lower pH levels using either sodium bisulfate or muriatic acid.

Make sure you know the precautions to take and the amount needed (read the manufacturer’s instructions) before using either method. While you’re at it, you can check the chlorine levels, but typically if the pool water is green, you aren’t using enough chlorine.

2. Shock the Pool

Chances are if your pool has algae, its chlorine levels are low. Adding chlorine shock not only gets the chlorine levels where they need to be, but it also kills the algae – our main goal here.

Use a pool shock treatment you’re used to using or that you have carefully read the instructions and know how to use. The best shocks contain at least 70% available chlorine. Use your testing kit to make sure you have the right levels of chlorine in the pool after shocking.

In general, to kill algae, you need 30 ppm chlorine. If your pool is still green after shock, you may have to shock the pool twice, depending on the depth of algae. If after two shocks you still don’t notice a difference or the water isn’t completely clear, do it again.

3. Scrub the Pool Walls

Once you’ve corrected the pool’s chemical levels, get in there with an algae brush and brush those side walls. This is one of the best methods when learning how to clean a green pool.

Use your pool brush to get as much as you can , and get the floor too. Keep going until all stubborn algae has been removed from the pool. Consider brushing off any pool accessories or pool toys that may have been in the water too. If you have an inground pool, make sure you sanitize your pool ladder as well.

Don’t be afraid to put in some elbow grease here – you want to loosen all algae to get it out of your pool.

4. Run the Filter

This is the most time consuming part of fixing dirty pool water, but it requires the least amount of physical labor.

Turn the pool filtration system on and let it run until the water turns clear. Let your filter system begin sanitizing, circulation helps move your pool chemicals around. This may not happen in a day or even two, it could take as long as five days.

Keep checking back to see how the water looks. If you have light green pool water, keepin going and always keep a close eye on the pool filter. If it clogs up, make sure you clear it right away.

If you have a sand filter or DE filter, make sure you set it to backwash to remove the harmful water from the pool.

5. Check the Water

Is the water still cloudy even after running the filter for a couple days? Use a flocculent to clear-up the cloudy pool water. Adding chemicals will help all leftover debris clump together. This makes it easier to get them out of the pool and keep it clean.

After using flocculant, vacuum the pool, removing all debris, leaving you with an algae-free pool.

6. Use an Algaecide

If you want to be extra sure you’ve removed all algae from the pool water, consider adding an algaecide. Not only will it kill off any remaining spores that you may not see, it helps your water remain clear moving forward, preventing further algae issues.

When you combine an algaecide with other simple methods to prevent a green swimming pool, you’ll have a head start on preventing issues in the future.

If none of these steps work or your pool water is so dark green that nothing works, you may need to drain the pool. Use this as a last resort but if you can’t make changes it may be your best bet.

Tips for Preventing a Green Swimming Pool

Once you get rid of the green pool water, take the steps necessary to prevent a green swimming pool from happening again. Chances are you don’t want to go through these steps again, they aren’t for the faint of heart!

Use these tips to prevent algae from building up in your pool again:

  • Keep up With Pool Maintenance– A clean pool means a lower risk of algae growth. Don’t just skim your pool, scrub your pool walls and vacuum the floor at least weekly, especially if you notice light green pool water. This prevents the buildup of debris and algae and ensures you don’t end up with green pool water.
  • Stay on Top of the Filters – Check your filter cartridge often. Is it clean residual residue and pool algae? Is it running properly? Water left to sit without filtering will easily build up algae. Check the filter for debris and clean it as often as necessary to ensure it’s running smoothly.
  • Keep the pH Levels Stable – Stay on top of your pool’s pH levels. Check them three times a week. Adjust the pH levels as necessary, keeping them within optimal range of 7.4 to 7.6.
  • Check Chlorine Levels – Always make sure your pool has the right amount of chlorine (not too much and not too little). Adjust accordingly to ensure your pool remains algae free.
  • Cover Your Pool – It’s a pain, but always covering your pool limits algae growth. It keeps debris out of the pool when no one is using it. Plus, it keeps the hot sun out of the pool, which can encourage algae growth if the pool water temperature changes quickly.

Goodbye Green Pool!

If your greenish pool water taught you anything, it’s that you must stay on top of your pool maintenance. You can’t undo the past, but you can prevent green water moving forward.

After you put in the hard work to get rid of the green pool water, set up a regular maintenance routine to ensure you don’t have to go through this again. Having routine pool care ensures your pool safety and is an important part of owning a water oasis.

If you aren’t sure about your pool’s chemical levels, bring a sample to your local pool store to get the water tested so you know beyond a reasonable doubt what your pool water needs.

How to Clear Green Pool Water Fast - Pool Care School (1)

Sean Moore

For over 15 years, Sean Moore has been sharing his love and enthusiasm for swimming pools and hot tubs with everyone he knows. His goal is to help everyday people DIY their maintenance to save money by teaching how to properly take care of your equipment, safely and correctly balance chemicals, and extend the life of your water oasis.


How to Clear Green Pool Water Fast - Pool Care School? ›

The fastest way to clean a green pool is to lower the pH level to below 7.2 and then shock the pool with chlorine. Use lots, and then use your pump and filters until it turns clear.

What is the fastest way to clear up a green pool? ›

The fastest way to clean a green pool is to lower the pH level to below 7.2 and then shock the pool with chlorine. Use lots, and then use your pump and filters until it turns clear.

How do I turn my pool water from green to clear? ›

Extreme heat, high winds, a dirty pool, incorrect pH levels, clogged pool filter, and rainstorms make algae blooms more likely. To clear green pool water, assess the situation, test the pH levels, shock the pool, filter the pool, and add algaecide and flocculant.

How do I get rid of green water in my kids pool? ›

  1. 1Decrease your pH level. To fix a green pool, you'll need to start by decreasing the water's pH level. ...
  2. 2Add super shock chlorine. Next you'll need to give your pool a shock dosing of chlorine. ...
  3. 3Clear up the water. ...
  4. 4Kill off any algae.

How do I make my green pool blue in 24 hours? ›

How do I turn my green pool blue?
  1. Shock the pool with chlorine every day until all the green is gone (possibly 3 to 4 days).
  2. Run the filter 24 hours a day and backwash every day until the green and then cloudiness is gone (usually up to 7 days, sometimes as long as 2 weeks depending on the filter).
Jun 10, 2016

Is it OK to swim in a green pool? ›

Green water is caused by various algae that are an integral part of aquatic life in lakes and other natural bodies of water. However, water is less safe for swimming in pools as it turns green. There can be many adverse effects to your health since algae in the water can spread E-coli and other vicious germs.

Can you over shock a green pool? ›

Can you over shock a green pool? No. The more chlorine shock you add to a green pool, the better chance it has to kill off all the algae. Follow the normal shock treatment based on the size of your pool and you can double, triple, or quadruple the dose to kill algae.

Can too much chlorine make pool green? ›

When the levels are properly balanced, chlorine will keep the algae at bay, but the water will slowly begin to turn green as the algae take over if there's not enough. But be careful—adding too much chlorine in pool water can cause those metals to oxidize and turn the pool a different shade of green.

Why is my pool green but chlorine is high? ›

The reason why your pool might turn green, even if you add a ton of chlorine, is because the chlorine can oxidize metals in the pool water, such as copper, iron, silver or manganese. Copper is especially prone to cause this.

What kills algae naturally? ›

Grab a brush and some baking soda. Bicarbonate, the active ingredient in baking soda, is an effective spot treatment to help kill the algae and loosen it from the wall.

Will chlorine fix a green pool? ›

Re-balance the pool water

You will likely need chlorine as pools usually turn green when the chlorine levels are too low.

What dissolves green algae from pool? ›

Adding shock to your pool super-chlorinates your water. And this extra dose of sanitizer will kill algae growth. The more serious your pool algae problem, the more shock you'll need. We recommend using calcium hypochlorite shock, or cal-hypo shock, as an effective algae treatment.

What turns a pool green overnight? ›

The most common reason pool water turns green is due to algae growing in the water. Algae can grow rapidly, particularly in hot weather, which is why it can surprise you overnight during the warmer months. This generally comes down to an imbalance or lack of chlorine in the water.

Can you clean a green pool in a day? ›

First, you need to know that you cannot clear a green pool in less than 24 hours, so this article is going to tell you how to clear it in around 4 to 5 days. The best method to keep your water clear is to have weekly or bi-weekly maintenance and cleaning done by a pool service company regularly.

How quickly can a pool go green? ›

Once the algae spores have the proper conditions to grow, they multiply very quickly, which is why your clear pool can turn green overnight. A pool full of algae isn't just unsightly – it presents potential health problems for bathers in the form of skin irritation, ear and eye infections, and gastrointestinal illness.

Why is my pool still green after shock and algaecide? ›

If your pool is green and cloudy, it's likely an algae problem. Algae can persist in a pool even after shocking. A green pool – especially one that turned green overnight or after rain, can also be from a pool pump that isn't properly circulating water or an issue with your filtering system.

How long after adding algaecide can you shock? ›

It is critical to understand that using pool shock and algaecide together can cause bad chemical reactions if the necessary precautions are not taken. Since your chlorine levels will not return to normal right after you shock your pool, we recommend waiting at least 24 hours to add algaecide.

How much shock does it take to clear a green pool? ›

Light Green or Teal Green Pool Water (early-stage algae): Double shock your pool with two pounds of shock per 10,000 gallons. Darker Green (significant algae growth): Triple shock your pool with three pounds of shock per 10,000 gallons.

Is a green pool high in pH? ›

If the pH is high, your chlorine is slow to react, and algae can begin to form, making the pool appear green or cloudy. If the pH is low, the chlorine will be “hyperactive”, reacting quickly, and dissipating out of the pool too rapidly, causing a low chlorine residual.

Why is my pool still green after shocking twice? ›

Pools can immediately turn green after shocking when they have metals like copper in the water. These metals oxidise when exposed to high levels of chlorine which makes the pool water turn green. Adding a metal control product such as Zodiac Metal Remover will help to restore the pool water.

Is it OK to touch pool shock? ›

You may be directly exposed to chlorine when adding it to your pool by tablet, liquid, or powder—a form called calcium hypochlorite. When calcium hypochlorite comes into contact with skin, it's highly corrosive, and its oxidizing nature can cause significant tissue damage!

Can I put bleach in my pool? ›

Answer. There's a protocol when using Clorox® Regular Bleach2 for swimming pool disinfection. On an ongoing basis, if you super-chlorinate the pool with 100-200 oz. bleach per 10,000 gallons of water, in addition to regular chlorination, algae growth can be prevented.

Does algae raise pH in pool? ›

Algae raises the pH of water too

Algae consume carbon dioxide, which removes it from solution. In effect, this consumption of CO2 raises the pH, and enough algae can raise the pH of your swimming pool well above 8.2.

Why is my pool green and wont hold chlorine? ›

You might have an infestation of algae, fungus or bacteria that can deplete normal chlorine levels and it is possible for this to occur without many visible signs. Your pool may appear to have a dusty look on the pool bottom. If you brush it and it clouds the water, then it is most likely a Mustard Algae.

What kills algae immediately? ›

Chlorine is still one of the most effective killers of algae so doing a super-chlorination of 10-20 ppm of chlorine can go a long way towards wiping out the algae. Liquid chlorine is an ideal shock for algae because it is fast acting and does not add cyanuric acid (CYA) or calcium to the water.

What kills algae permanently? ›

Bleach is great for killing algae (and other organisms that may lurk in your tanks) and for keeping it from coming back. Scientific research shows that using bleach that is made from a solution with 5.25% hypochlorite. Never mix bleach and chlorine together.

What destroys algae? ›

If algae grow on the leaves and stems of your aquarium plants, create a routine of cleaning them regularly. Using a solution of 5-10% bleach, dip the plants for a few minutes as needed to destroy the algae.

What kills pool algae the best? ›

"Shocking" the pool with a large dose of chlorine is the most effective way to kill the existing algae and bring your pool back to sanitary conditions. This usually works within 1–3 days, but can take up to a week if pool conditions are poor.

How long does it take to clear algae in pool? ›

How long will it take to clear the pool? A fiberglass pool in its worst condition can be algae-free in 24 hours. For a vinyl liner pool, the process can take 3-4 days. For a concrete pool, this can take a week or more.

Will baking soda clear a green pool? ›

Baking Soda and Green, Blue, or Yellow Algae

You'll need to use an algaecide to kill the algae and superchlorinate your pool to clear the water. After this treatment, test your pH and alkalinity and add baking soda to raise alkalinity to at least 100 ppm and pH to between 7.2 and 7.8.

Can you swim in a pool with algae? ›

But is it safe to swim in a pool with algae? Whether mild or severe, it isn't recommended. Significant amounts of swimming pool algae welcome a breeding ground of harmful bacteria that feed on algae. These bacteria pose health risks to swimmers, most commonly resulting in a skin rash.

How long do you backwash a green pool? ›

Green or cloudy water will quickly clog a filter, therefore you may have to backwash your filter twice daily until the pool clears. Run the backwash cycle for 60 – 90 seconds. The more you run your pool, and the more you backwash the filter, the faster the pool will clear up.

How do I fix my green pool overnight? ›

Follow these steps to treat and prevent green pool water.
  1. Test and Balance Water. Always begin by testing your pool water. ...
  2. Clean Pool Water and Surfaces. Skim water surface to remove visible debris, brush walls, vacuum and empty skimmer baskets. ...
  3. Apply a Shock Treatment. ...
  4. Apply an Algaecide. ...
  5. Clean Filter.

How long does a green pool take to clear? ›

The fastest way to clean a green pool is by using pool chemicals and your pool filter. This process usually takes around 4-5 days but you will start noticing a major improvement after 24 hours.

How many days does it take to clear a green pool? ›

If your pool is still green after 24 hours, there may be too much of the wrong chemicals, for example an excess of phosphate or cyanuric acid (“stabilizer”). It will take a while for the cloudiness to go away. For a sand filter, it will take a week or more.

What kills algae in a pool fast? ›

Adding shock to your pool super-chlorinates your water. And this extra dose of sanitizer will kill algae growth. The more serious your pool algae problem, the more shock you'll need. We recommend using calcium hypochlorite shock, or cal-hypo shock, as an effective algae treatment.

How much shock is needed to clear a green pool? ›

Light Green or Teal Green Pool Water (early-stage algae): Double shock your pool with two pounds of shock per 10,000 gallons. Darker Green (significant algae growth): Triple shock your pool with three pounds of shock per 10,000 gallons.

Why did my pool turn green in 2 days? ›

The most common reason pool water turns green is due to algae growing in the water. Algae can grow rapidly, particularly in hot weather, which is why it can surprise you overnight during the warmer months. This generally comes down to an imbalance or lack of chlorine in the water.

Can I swim 12 hours after shocking pool? ›

Can you swim in the pool after you shock a pool? You need to wait for at least 8 hours and up to 24 hours after using a chlorine-based shock before you can swim. And you'll want to retest your water to make sure your chemical levels are within range.

How do I turn my pool from green to blue? ›

How to turn your pool from green to blue in six simple steps
  1. Remove leaves and debris. ...
  2. Clean the pump and filter. ...
  3. Vacuum the pool. ...
  4. Chlorinate the water. ...
  5. Scoop and vacuum. ...
  6. Begin regular maintenance.
Dec 23, 2019


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