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Nobody really wants to swim in milky pool water that looks more like an empty bowl of cornflakes than a swimming pool.

Cloudy pool water doesn’t just look unappetizing.

Depending on the exact cause, cloudy pool water can be a sign that dangerous bacteria are settling and multiplying in the pool.

As a result, the pool can be damaged, the pool equipment can be damaged, or even your health can suffer.

Avoid health risks and costly damage by quickly finding out the cause of cloudy pool water and responding appropriately.

The right treatment depends on why the pool water became cloudy.

Therefore, let’s first ask ourselves the most important question:

Why does the pool water become cloudy or milky?

The causes of cloudy pool water can be found in the filtration system and pool chemistry. To avoid cloudy pool water, both should be optimally adjusted.

The pool will quickly become clean again once it has been thoroughly cleaned and the framework conditions for good pool maintenance have been restored.

In the following, we will get to the bottom of the problem. Let’s start with the possible causes.

Causes of cloudy or milky pool water.

From one day to the next, pool water can become cloudy. Normally, however, cloudiness doesn’t develop overnight; it’s a slow process. Initially, you may notice that the water appears somewhat milky.

When swimming, this is not noticeable at first and does not bother you. Only after a few days does the problem become obvious.

But if you don’t take immediate action with your pool, you have a lot of work ahead of you. So, what are the causes of cloudy or milky pool water?

#1 Lack of disinfectant (such as chlorine or bromine)

Debris in the pool is attacked by your disinfectant (such as chlorine). However, the disinfectants are not designed for large amounts of solids. For this purpose, there is the filter system.

If the filter does not remove the solids from the water, or you assist with a pool vacuum or pool net, the sanitizer will be used up quickly.

Another major cause of disinfectant consumption is the bathers themselves. Sunscreen and body and hair care products are carried by people into the pool water and are also fought off by the chlorine. Likewise, body fluids such as sweat and urine consume the disinfectant.

An algae problem can also increase the amount of chlorine (or bromine) needed. Of course, no one wants to swim in a pool with algae anyway, and the high consumption of disinfectant also causes the water to quickly become milky.

Solar radiation also causes a loss of disinfectants. The sun’s ultraviolet rays break apart the disinfecting hypochlorite ions that form when you add chlorine (e.g. in the form of chlorine tablets) to your pool. The broken-up ions from the disinfectants evaporate into the air.

The piles of leaves and personal care products in the water keep the chlorine busy. These organic contaminants are bound by the chlorine. Additionally, other reasons contribute to a loss of disinfectants. This leads to the need to add more disinfectant.

Losses due to solar radiation and dilution due to water loss also lower the effectiveness of the chlorine. All of this makes the chlorine less effective at killing algae and dangerous pathogens and bacteria like E. coli. Not only does your pool become cloudy, but it also puts your health at risk.

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Pool Mate 1-1308 Granules Swimming
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#2 The filter system does not work properly

The filter system is the circulation system of your pool. If problems occur here, the water will quickly become cloudy and dangerous for bathers. 

If everything is working well and the filtration system runs for at least eight hours per day, sediment should be minimal. The filter, along with disinfectant, will remove all kinds of contaminants from the pool.

However, a filtration system also requires maintenance. Clean the filter and replace cartridges regularly to keep it working properly.

A filtration system also ages, and not very well. If contaminants are no longer removed from the water, they will accumulate in your pool and lead to a chain of action of more used disinfectant and bacteria finding more organic material as food, which in turn leads to more contaminants.

Ready after a short time they are dealing with all sorts of different water problems.

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CIPU 12-inch Sand Filter Pump
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#3 Something is wrong with the pool chemistry

This is the moment when you wish you had paid better attention in school. However, you actually have no reason to worry. You quickly learned a basic understanding of pool chemistry.

If your pool chemistry is not in balance, it is more a matter of when, not if, you wake up one day and your pool is murky.

With unbalanced pool chemistry, milky pool water is then one of the smaller problems. Health risks, gross pool contamination and corrosion of pool accessories are other consequences.

If you let pool maintenance slide, don’t be surprised if after two or three weeks the crystal clear water turns into a murky broth.

High alkalinity, high pH, high calcium hardness or even too much disinfectant in the water can cause cloudiness. Even shocking the pool – in an otherwise clean and perfectly balanced pool – can cause temporary cloudiness.

Pool water cloudy – is that a problem?

Now you know the possible reasons why your pool might be milky.
But is that a big deal? Sure, the cloudiness doesn’t look so pretty, but in fact, cloudy pool water is often a symptom of more serious problems.

Problem #1: Low filter efficiency

Cloudy water can be an indicator of a clogged filter, filtration system failure, or a pump that is slowly giving up the ghost. The pool will not clear should such a filtration system remain in operation.

If the filtration system is not working properly and for at least eight hours a day, cloudy pool water may result. Only a fully functioning, clean filter can protect your water from sediment.

With a filter system that is not working efficiently, the sanitizer will be used up faster. The pump will have to work harder to move the water to the filter where it will not be fully cleaned.

The result is dirty-looking water that is loaded with bacteria and can be hazardous to bathers’ health.

Problem #2: Lots of bacteria in the water

Disinfectants like chlorine or bromine play an important role in keeping the swimming pool clean. Cloudy water is a sign of a lack of disinfectants. The cause of this can vary. If there is a lack of disinfectants in the water, bacteria and pathogens such as E. coli and Legionella can multiply.

Problem #3: Too much chlorine

High chlorine concentration can cause skin and lung irritation. People with respiratory diseases such as asthma or bronchitis are particularly at risk. Furthermore, chloramines, which are by-products of treatment with chlorine, can cause corrosion and also irritation.

Problem #4: Alkalinity, pH, calcium or heavy metal content too high

Alkaline pool water has a pH that is too high. It can cause bacteria and algae growth, calcify pool walls, wear out metal and vinyl, and clog the filtration system. The result is cloudy water in the pool.

Pool water with high alkalinity can attack the metal and cause wear on the vinyl. Calcium, on the other hand, is the cause of scaly deposits that cloud the water and clog the filter. Heavy metals such as copper or zinc can have a similar effect.

Problem #5: Algae infestation

Cloudy water is often accompanied by algae infestations. The types of algae that colonize pools are not necessarily harmful. However, if you have algae in your pool, suspended solids from dead algae will cause a high degree of turbidity.

Highly turbid pool water poses a risk to children and animals. A pool with dead algae makes it impossible to see the bottom of the pool. Since drowning people hardly draw attention to themselves and the turbidity gives you no way to spot them underwater, you should block access to your pool until you solve the problem.

How to Clear a cloudy Pool in 5 Steps

Now that you’ve learned that cloudy pool water can indicate serious problems, it’s time to clear the pool. One time does a decent amount of work. In return, your pool will sparkle again after the cleaning.

Step #1: Thorough cleaning

The first step is to do a proper cleaning. Brush down the walls with a pool brush. For a solid pool made of plaster or concrete, for example, brushes with steel bristles work well.

Vinyl walls you would damage with steel bristles, in this case choose softer bristles made of nylon, for example.

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POOLAZA Pool Brush, 17.5" Pool
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Now remove large debris and anything you brushed off with a pool vacuum.

Step #2: Vacuum the bottom

The skimmer is on the surface of the pool and will not manage to suck in sediment from the bottom. If you have a drain at the bottom of the pool, you should use it.

If your pool doesn’t have a drain, you can use your pool vacuum instead to suck dirt and foreign particles from the bottom.

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Swimline Weighted Flex Vacuum Head,
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Step #3: Shock the pool

Now you should shock your pool. Using a high dose of chlorine will kill algae, bacteria and all sorts of organic material in the pool. As an alternative to the chlorine-based solution, there are also chlorine-free pool shockers.

If you have a heavy algae infestation, you may need to shock the pool multiple times.

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HTH Pool Care Shock Advanced,
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Step #4: Filter the water thoroughly

Before you start filtering the water, the filter is thoroughly cleaned or the cartridge is replaced. 

Start the filter after adding the pool shocker to ensure that the pool shocker is flushed through the filtration system and provides clean water throughout the circuit. Now leave the filtration system for 48 hours without a break.

Step #5: Balance the pool chemistry

Once the pool is clean again, it’s time to test the water quality. You can test it yourself with a test kit or test strips, or have it professionally tested at a specialty store.

Add chemicals as needed until the pool chemistry is back in balance. You can use a chlorine stabilizer such as cyanuric acid to keep chlorine levels at a constant level.

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How to clear a cloudy saltwater pool

So far we have only talked about normal chlorine pools, but what if the saltwater pool contains cloudy water? 

Basically, the milky or cloudy water in the saltwater pool is no different from that in a chlorine pool. Therefore, the same measures apply to saltwater pools to make the pool water clear again.

The question, however, is why cloudiness or milky discoloration has occurred. At this point, you should take a close look at your salt system and make sure everything is set up correctly.

Tips against cloudy pool water

Here are a few more tips to help you prevent cloudy pool water from occurring, or to help get rid of the cloudiness as quickly as possible.

If you have visitors coming and the cloudiness isn’t quite as severe, a flocculant may do the trick. When the agent has fully soaked in, clumped debris will sink to the bottom. Now you can vacuum them up with a pool vacuum cleaner. Discharge the vacuumed water as wastewater so it disappears from your pool system.

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Clorox Pool&Spa Sink to Clear
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Water clarifier is the best way to prevent cloudy pool water in advance. Add water clarifier to the pool as part of your weekly water maintenance. Water clarifier is not the solution to any of the above problems, but it does help keep a well-maintained pool looking crystal clear.

This water clarifier is good for clearing pool water quickly:

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Robarb R20154 Super Blue Clarifier
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Making a murky pool clear again is not a huge effort. To prevent it from happening in the first place, keep up with your pool cleaning schedule. Testing the water weekly, removing anything that has strayed into your pool, and shocking the pool regularly are all part of the process.

Remove leaves and other debris from the water with a pool vacuum and a landing net. This way, you’ll make the filter’s job easier and reduce the need for disinfectant.

Also, avoid foreign objects from getting into your pool in the first place. Shower off before taking a dip in the pool and cover the pool with a pool tarp when not in use.

If you follow these tips, your pool can (almost) never get cloudy.

The pool does not become clear – what now?

Sometimes it is unfortunately so – the pool does not become clear, no matter what you try. There is only one thing that will help here: drain the pool completely and, with the pool drained, perform a complete cleaning of the walls and bottom. 

Also clean and disinfect the pool accessories that will later come into contact with the new pool water. Whether pool robots or toys such as inflatable water animals. 

Afterwards, you should proceed in the same way as you would when filling the pool for the first time. This should ultimately clear even the most stubborn pool.

FAQ

How long does it take for the pool to clear?

If the pool has been very cloudy, it can take up to 48 hours for the pool to clear completely.

Is cloudy water in the pool harmful?

Cloudy water in the pool can indicate dangerous pathogens and bacteria such as E. coli. The more turbid it is, the more of a health hazard it poses.

When is pool water tipped?

Slightly green water can be treated with the correct method. If the discoloration is severe, the pool water is tilted and should be completely replaced.

Can you bath in a cloudy pool?

Here it depends on the degree of turbidity. Basically, bathing in turbid water should be avoided, as there is always a health risk.

Larry has been a true water rat since childhood. Pure pleasure turned into a passion. That's why he is the first point of contact for friends and acquaintances when it comes to pool-related problems. He is an integral part of the PoolHandbook editorial team.