Cloudy Pool Water

Cloudy Pool Water - Ultimate Guide To Fixing It

Cloudy pool water can be a pain to diagnose because there are several pool conditions that can cause it. If you have tested your pool’s chemistry and found no imbalances, and your filter system appears to be functioning normally, you may be especially stumped.

Read on to learn more about the many different causes of cloudy pool water, how these causes might appear differently, remedies to clear up your water, and how to prevent cloudy pool water from reoccurring.

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Causes of Cloudy Pool Water

Chemical Imbalances

Imbalances in the chemistry of your pool are a common cause of cloudy pool water, with the most common causes being low chlorine or imbalanced pH specifically. There are also other water properties known to affect water clarity, such as the total alkalinity and calcium hardness.

Water cloudiness caused by chemical imbalances typically appears as a milky tone, without any other colours present that could be indicative of other issues. Essentially, your pool will be blue but cloudy.

To confirm that your water cloudiness is caused by a chemical imbalance, we recommend testing your water’s level for each property mentioned.

Use a general strip test or test kit that can measure parameters like free and total chlorine, pH, hardness, total alkalinity, and stabiliser.

Poor Filtration

Poor water filtration is another common cause of murky water. We recommend running your pool’s filter system for a minimum of eight hours each day, but this may not be long enough in some cases, such as in areas with higher amounts of pollutants or swimmers.

Pool water that is not adequately circulated is at risk of developing bacterial growths that are commonly found in stagnant water and form on accumulated debris.

Poor filtration can lead to many types of cloudy pool water, although it typically presents as slightly muddied water.

This is a common cause of cloudy water, even if the water chemistry is fine.

Superfine Particles of Debris

Many forms of debris introduced into your pool consist of polluting particles that are too small in size to be removed by your filter system, even when your filter is functioning at peak performance.

Tiny debris is often introduced by swimmers in the form of sunscreen and other haircare or skincare products. It can also be introduced to your pool through dust in the air, such as pollen or ash from wildfires, and this effect is increased when your pool collects rainwater.

Pools with an accumulation of superfine debris may appear cloudy in a way that is yellow or sepia in tint, and can even appear brown or muddy if dirt has entered the pool.

Algae Infestations

Algae infestations can also cause water to become cloudy, although this is unlikely to be the cause of your pool’s cloudy water if no other signs of algae are present. In order for algae infestations to cause cloudy water, they must be actively reproducing.

This means that there will already likely be an untreated buildup of algae growths on the surface of your pool before your pool contains enough algae to cloud the water column.

It also means that your pool’s sanitising agents are not functioning properly, pointing to a strong likelihood of a chemical imbalance, particularly insufficient free chlorine.

If an algae outbreak is the cause, you will notice that your pool looks green and cloudy. The water will be quite hazy and you might not be able to see the bottom.

How to Fix Any Type of Cloudy Pool Water

Fixing Pool Filtration

First, ensure that your filter system is running properly. Check your skimmer basket, water intake and output zones, as well as any other accessible pump hoses for blockages.

Then, clean your filter using a stiff-bristled brush. The brush should be stiff enough to clean your filter, but not tough enough to damage it (like a wire brush would).

If you cannot get your filter adequately clean, you should invest in a replacement filter. Filters become clogged with debris over their natural lifespan, slowly decreasing their effectiveness in your pool.

Removing Tiny Particles of Debris

To remove tiny particles of debris that are not able to be removed by your filter system, you will need to use either a clarifier or flocculant in your pool. These help to remove small debris particles from your pool.

Clarifiers work by coagulating particles of debris in your pool, causing them to stick together in groups that then become large enough to be removed by your filter system. We recommend the Algon Clarifier, which will work to restore clarity during hours that your pump is operational.

Flocculants are another great option for removing tiny particles of debris or clearing up muddy pools, but these products require more maintenance. Rather than being removed by your filter system, debris that is coagulated by a flocculant must be removed from your pool through vacuuming.

One benefit that flocculants have as opposed to clarifiers is their ability for quick results. Algon Floc is ready to be vacuumed after 5-6 hours, offering to return your water to its crystal clear, blue state much faster than a clarifier if you are willing to invest the manual effort.

Restoring Chemical Balance

To restore chemical balance to a pool that is cloudy from low chlorine, simply increase the concentration of chlorine in your pool using the guidelines specified on your product’s packaging. An ideal range of free chlorine for your pool falls between 1-3 parts per million (ppm).

When fixing cloudiness caused by imbalanced pH, you may need to increase or decrease your pool’s levels depending on the results of your test. The ideal pH level for pool water falls between 7.2-7.8.

Soda ash, also known by its chemical name ‘sodium carbonate’, is exactly the product you need to increase pH level in your pool.

To reduce pH in your pool, you will need a dry acid such as sodium bisulphate, commonly sold as pH decreaser.

Cloudiness caused by an imbalance in total alkalinity levels can also be remedied by using these same products, with sodium bicarbonate another option for raising alkalinity while having minimal impact on pH.

The ideal range for total alkalinity in a pool is 80-120ppm, as cloudiness and other pool problems can occur when levels fall outside these guidelines. Use this baking soda calculator to work out the right dose of sodium bicarbonate for your pool.

High water hardness can also cause cloudy water. The appropriate range of water hardness for pools is between 150-400ppm, and lowering high water hardness usually requires that your pool’s water be partially drained and then replaced with fresh water.

Eradicating Algae Infestations

Algae outbreaks can lead to a variety of problems with your swimming pool in addition to cloudy water, which makes eradicating an algae infestation incredibly important for the health and safety of your pool and its swimmers.

If you think your cloudy water is caused by algae, you will likely have noticed algae forming on the sides of your pool.

We recommend that you treat your pool with an algaecide or a shock treatment to begin your algae removal process.

Some algae infestations are particularly difficult to remove, such as those involving a species known as black spot algae. If you suspect your pool to have this type of algae, we recommend following a removal method designed specifically for this strain.

See this guide on dealing with black algae in a fibreglass pool, and this one for pebblecrete pools.

Preventing Cloudy Pool Water

While restoring your pool water back to its crystal clear state is good, keeping it there in the future is even more important.

Here’s some tips on how to prevent the cloudy water from coming back!

Keep Pool Clean

The best way to prevent cloudy pool water is to keep your pool adequately cleaned. This involved removing debris that accumulates during inclement weather, regularly emptying your skimmer baskets, and cleaning your filter on occasion.

Unattended pool debris leads to the release of phosphates, bacterial growth, and algae problems, all of which can detract from the appeal of your pool and be potentially harmful to swimmers.

Maintain Balanced Chemicals

Cloudy pool water that is caused by poor chemical maintenance can be prevented by regularly testing and adjusting your chemical levels.

Testing your chemicals is usually recommended once per day, with most accurate readings being found in the mornings or the evenings, outside of the hottest part of the day.

Chemical adjustments should be made as soon as you notice your levels are off.

Imbalanced chemicals can have a snowball effect in your pool that causes other chemicals to become imbalanced, decreases the efficiency of your sanitising agents, and may cause water to become corrosive to pool equipment or swimmers.

If algae outbreaks are a persistent problem, keep an eye on your phosphate concentration. Consistently high phosphate levels can feed algae and make it difficult to keep on top of them, even with regular chlorine dosing.

Use a Preventative Product

For pool owners that encounter cloudy pool water regularly, whether it be due to rain, swimmers, or slow buildup of pollution from other sources, we recommend the use of a preventative product designed to maintain pool clarity.

We like Crystal Clear Floc Blocks, which is a low maintenance option that slowly dissolves in your pool’s skimmer basket. As it slowly dissolves, the components of the cube actively work to lower phosphates and allow fine particles of debris to be more easily captured by your filter system.


Cloudy pool water can be a nuisance, but it doesn't have to be one for long. Our handy guide for diagnosing and treating the source of your pool’s foggy haze can help you get to the root of the problem in no time.

Do you have any remaining questions about cloudy pool water? Leave a comment down below, we’d love to help you out!

Louis from Pool Advisor


A chemical engineer by trade, Louis is committed to debunking myths in the pool industry by explaining the underlying chemistry and making it accessible to all.