How to Clear Cloudy Pool Water

Nothing is more appealing on a hot summer day than a pool filled with crystal-clear water. So it can be a big disappointment when pool water is cloudy and unappealing. There are many possible causes for murky pool water, so let’s examine the many ways to clear cloudy pool water.

How to Clear Cloudy Pool Water

Is it Safe to Swim in a Cloudy Pool?

There is a wide range of water conditions that cause a cloudy pool. Some of them are simply aesthetic, and the pool may be safe to swim in. However, cloudy water is often an indication of water problems.

The Centers for Disease Control advise swimmers to avoid cloudy water and only swim when you can clearly see the drain at the bottom of the pool’s deep end. Some of the risks of swimming in a cloudy pool are as follows.

Cloudy Water May Indicate the Presence of Germs

Because chemicals like chlorine and bromine kill germs and keep the water clear, cloudy water may indicate the presence of disease-causing germs. Germs in pools can spread recreational water illnesses like skin, ear, and eye infections. The most common disease-causing germ in pools is E. coli, which can pose serious health risks to vulnerable people.

Cloudiness Impairs Water Safety

When pool water is cloudy, it may be more difficult to see struggling swimmers underwater. That’s why it’s always essential to make sure you can clearly see the drain at the deep end – water safety means clear visibility all the way to the bottom of the pool.

Unhygienic Water

Even if cloudy pool water isn’t contaminated with germs and bacteria, it may simply be dirty and unhygienic. Murky water can be caused by body oils and ointments, dirt and debris from water runoff, or algae and insects. When you think about it, nobody really wants to swim in dirty, oily water.

In other words, you should avoid swimming in a cloudy pool unless you know exactly what’s causing the cloudiness and know that the water is safe and hygienic. Here are some of the most common causes of cloudy pool water.

Causes of Cloudy Pool Water

As you’ll see, nearly anything can make pool water cloudy. However, here are some of the most common causes.

Low Chlorine Levels

The most common cause of cloudy pool water is low levels of free chlorine. Chlorine may have been diluted by rainfall or be less effective due to contaminants or low stabilizer levels.

Early Algae Growth

Early stages of algae growth may appear as water cloudiness and lack clarity before developing into the familiar green film.

High Ammonia Levels

When a pool remains cloudy despite the addition of chlorine, it is often due to high ammonia levels.

Improper pH Levels

High pH reduces the effectiveness of chlorine and can cause cloudy pool water. High pH can also cause calcium precipitation, making the water cloudy.

Excess Calcium

Calcium interacts with alkaline water to precipitate and cause cloudiness. High calcium levels can also cause scaling or make the water cloudy at high temperatures.

Imbalanced Stabilizers

Cloudiness can be caused by phosphate, bromine, cyanuric acid, and other stabilizing chemicals when they are out of balance.

Filter Problems

A cloudy pool may have a dirty filter, a filter that isn’t functioning correctly, or simply a filter that isn’t operating for long enough to clear pool water.

External Contaminants

Heavy rainfall can affect your water chemical balance and add unwanted minerals, mud, or debris into the pool.

A pool may also become cloudy due to other contaminants like dust, leaves, insects, bird droppings, and the like. In addition, body oil, sunscreen, and other products used by people swimming in your pool can cloud the water.

Because there are so many factors that cause pool water cloudiness, it may be necessary to try a wide range of different solutions to address it. However, once you know what causes the cloudiness in your water, you can more quickly zero in on the solution.

How to Clear Cloudy Pool Water

Depending on the cause of cloudiness, there is a wide range of solutions. If you aren’t sure of the cause, it’s best to troubleshoot by systematically working through a list of possible solutions. Here is how to turn your water from cloudy to clear.

Check and Run Your Filters

While filter problems aren’t the most common cause of cloudy pool water, it’s the easiest place to start. Cloudy water is often caused by clogged filters or filters that simply haven’t run for long enough.

First, look at the pool return to see if the filter is returning cloudy or clear water: You can sometimes merely see if the filter is working correctly. Then, run your pool filter for at least 8 hours or for the proper length of time to turn over your entire pool.

Test Your Chlorine Levels

Because chlorine levels are the most common cause of cloudy water, the first step is to test your free chlorine levels. High chloramine clouds water, creates the famous “chlorine” smell and does not sanitize your pool.

Use a test kit and look for free chlorine (FC) that is a minimum of 7.5%/CYA. If you have low FC, add chlorine and test again in a few hours, and test again 24 hours later. If your pool water remains cloudy and your FC levels remain low, move on to the next solution.

Balance Your pH/ Total Alkalinity

High pH/total alkalinity is another common cause of cloudy pool water, so don’t simply add soda and hope to clear a pool. Instead, test the water and look for a pH of approximately 7.5 and total alkalinity of 120-150 ppm.

Having the correct levels of total alkalinity stabilizes your pH and prevents rapid changes, so adjust both levels accordingly and test after 24 hours. If your pool water is still cloudy, move on to the next step.

Perform Filter Maintenance

If your water chemistry won’t stabilize and your pool is still cloudy, take another look at the filter. Depending on the type of filter you have, you may need to open the cartridge or remove the grid. Look for dirt and discoloration, cracks, or fraying, and check the seams and fabric.

If you have a sand filter, drain the filter and run your fingers through the sand, looking for clumps of mud, calcification, or other impurities. If your pool filter looks dirty, it may simply need to be cleaned.

If it looks damaged, it may need to be replaced. Try backwashing your filter and see if that clears the pool water. If it doesn’t, move on to the next step.

Scrub and Vacuum the Pool

Regular cleaning helps to keep pool water clear and may help clarify pool water where algae are forming. Use a brush to scrub pool walls, especially around areas with lower water circulation, like pool ladders.

Use a pool vacuum to clean dirt and loose debris off the bottom of the pool. Scrub the pool whenever pool walls start to feel slick to the touch.

Shock Your Pool

If you’ve tried everything else and the water is still cloudy, it’s time to shock your pool. Keep in mind that pool shock is most effective when the pool is already scrubbed and free of debris and the pH/alkalinity is already balanced, so it’s not always a good idea to skip ahead to this step.

Shocking a pool means adding enough chlorine to not just kill germs and bacteria, but to break apart chloramine particles, lowering CC and raising FC levels to create more stable water chemistry.

When chlorine levels remain low and won’t stabilize, or CC levels are above .5, it’s time to shock your pool. To shock a pool:

  • Wear protective eyewear, sturdy gloves, and work clothes that won’t be damaged by bleach. Pool shock can severely irritate eyes and skin, so wear protective gear and remain upwind as you work with shock. Wear long sleeves and closed-toe shoes.
  • Prepare your shock. There are many different brands of pool shock. Calculate the amount you need for your pool, and prepare it according to the manufacturer’s instructions.
  • Add the shock to the pool. Again, follow the manufacturer’s instructions to determine how to add the prepared shock to your pool. Some products are recommended to be distributed around the pool edges, while others should be added near the jets.
  • Wait the recommended amount of time. Most pool shocks need to be left for at least 8 hours with the pump running, so leaving the shock overnight is often the best choice.
  • Test your water chemistry. 8-24 hours after shocking, testing your chlorine and pH levels and adjusting if necessary.
  • Keep the filter running and/or re-vacuum the pool. Shocking the pool is intended to kill microorganisms that aren’t killed by your standard chlorine levels, but that dead organic matter can still leave your pool cloudy. Keep the filter running for at least 24 hours after shocking, and/or re-vacuum the pool to remove that debris.
  • Use a water clarifier. Water clarifier can be a great choice if your pool is:
  • Clean and chemically balanced
  • Filters are clean and working properly
  • Free of algae and contaminants
  • You can see the deep end drain, but you still have mild cloudiness

In these instances, cloudiness may be caused by microscopic debris simply too small to be removed by the filter. A pool water clarifier is explicitly designed to help with this type of cloudiness. There are two types of pool water clarifying products to consider:

  • Standard pool clarifier. A regular pool clarifier works by coagulating tiny particles into larger particles, using a polymer that collects debris into a size large enough to be removed by your standard filter.
  • Pool flocculant. Pool flocculant is much more powerful than standard clarifiers. It collects tiny floating debris into larger particles that precipitate out of the water and accumulate on the bottom of the pool.

It’s essential to always read the manufacturer’s instructions. Still, as a general rule, you shouldn’t use a pool floc with a cartridge filter and will have to vacuum the precipitated particles out of the bottom of the pool after using it. Standard clarifier works more slowly but is easier and a great solution for mild cloudiness.

All you have to do is add it to the pool according to the manufacturer’s instructions, run the pool filter for 24 hours, and then clean the filter. When you know your pool is clean and healthy but can’t seem to get the water completely clear, a pool clarifier is an excellent choice.

Read the label to determine which type of clarifier is best for your needs, and follow the instructions carefully to address cloudy water once and for all.


While cloudy pool water is not always a sign of unhealthy water, it can create a safety risk and should be taken care of. In most instances, keeping pool water at the proper chlorine and alkalinity levels, regular cleaning, and regular filter maintenance will help you keep a pool crystal-clear and beautiful.

If not, water clarifiers are explicitly designed to treat cloudiness in pool water that is otherwise clean and healthy and can help create that beautiful, appealing, clear water that invites swimming and relaxation. So now you know how to create clear, un-clouded pool water, no matter what the cause.

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