Cloudy Pool Water Causes and Solutions

How to Clear Up Cloudy Pool Water?

Having your own pool is great. No more swimming in crowded public pools or paying for tickets to get in all summer. The only trick is that having your own pool means doing your pool maintenance, and, if you’ve ever had something go wrong, you know how serious a problem it can be.

One of the most common concerns for home pool owners is cloudy water. It can be hard to understand how a pool can go from crystal clear water one day, to cloudy the next.
Here’s what you need to know about what cloudy pool water is, what it means, the risks and health problems associated with it, and, most importantly, how you can get your pool water clean and clear again.

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Cloudy Pool Water: What It Is and Why It Happens

Cloudy pool water is a common but frustrating issue that many pool owners face, especially during the peak swimming season. It refers to water that looks hazy, dull, or milky instead of clear and sparkling. This cloudiness can be caused by a range of issues like imbalanced chemicals, poor filtration, algae growth, or even environmental debris.

Identifying the right cloudy pool water solution depends on knowing what can make a pool cloudy in the first place.

Causes of Cloudy Pool Water

There are 7 main causes of cloudy pool water, and it’s important to know each of them so you can correctly diagnose and fix the problem.

Following are the 7 main causes:

Improper chlorine levels or balance
Imbalanced PH (your pool may be too alkaline)
High calcium hardness
Faulty or clogged filtration
An early phase of an algae bloom
Excess ammonia
Excess debris
High organic load usually from lotions, oils, or cosmetics
Equipment problem (Leak on multi-port valve on a sand filter)

Learn More about Pool Alkalinity

Thankfully, for the 4 most common causes of cloudy or foggy pool water, there are also straightforward solutions.

However, all of these problems can potentially pose a health and safety risk for anyone using the pool. So if you notice cloudy pool water, it’s best to avoid swimming until you’re able to test the water and fix whatever is causing the problem.

How to Diagnose Cloudy Pool Water?

The most common cause of cloudy water is a low level of free chlorine. This might sound backward, but having a low level of free chlorine can actually mean that your pool smells more strongly of chlorine than it would normally.

Ideally, your free chlorine, or FC levels, should be between 1-3 ppm (parts per million) or combined chlorine above .5ppm, you will need to shock your pool to fix the chlorine problem and clear the water. In saltwater pools, this means shutting down your chlorine generator and manually shocking the pool.
However, in the summer or just after you get your pool up and running again after the winter cold, you could also be dealing with ammonia or algae. This happens because of low FC, and also because your cyanuric acid levels are low. Unfortunately, the best solution here is also to add a lot of chlorine (shock) to the pool to clear the ammonia and help your filtration system get back to normal working order.

Other problems, like imbalanced chemicals, a faulty filter, or environmental factors (like having a lot of dust settle in your pool because your next-door neighbor is doing a lot of landscaping or construction) can be solved by testing your pool water and adjusting accordingly.
If the cause of your cloudy water isn’t immediately obvious, running tests on water quality can help you diagnose the problem.

Solutions for Cloudy Pool Water

The most common solution for foggy pool water is either increasing your filtration to make sure you’re getting enough circulation or adding more chlorine to help restore the proper balance of chemicals.

Knowing which cloudy pool water solution you need to take can be a more difficult part of the process.

Test Chemical Levels: First, you need to test the water. Any pool owner should have a standard pool testing kit that shows the level of each chemical your pool needs and tells you if you’re at the right concentration.
Pool Size & Chemical Accuracy: You also need to know the size of your pool so you can calculate how much of each chemical you need if you’re making corrections. Over-chlorinating your pool can cause as many issues as under-chlorinating it.
For instance, if you have high pH due to high Total Alkalinity (TA) you can add muriatic acid. Simply reducing your pH could help resolve cloudiness and calcium scaling.
Mineral Buildup / Hard Water: For other problems, like high calcium scaling and hard pool water, the only effective cloudy pool water solution is to partially drain the pool and refill to reduce the mineral buildup in the water.
Improve Filtration Runtime: Increasing the pump and filter runtime will also help removing suspended matter which is often the cause of cloudy pool water.
Add Pool Clarifier: Adding a pool water clarifier can further enhance filtration effectiveness and clear up foggy pool water.

Preventing Cloudy Pool Water

Most important in all of this is learning to prevent cloudy pool water in the first place. Getting cloudy water almost always means extra time and expense before you’ll be able to use your pool again. These problems are almost entirely preventable with good pool maintenance and monitoring.

Some tricks to prevent foggy pool water include:

Pool shocking weekly
Maintaining chlorine levels between 1-3ppm
Keeping PH between 7.2-7.6 (just slightly acidic)
Running your pump for at least 8 hours every day
Regularly replacing filter cartridges
Perform filter inspections at least 2x a year
Use a pool brush to sweep any debris away from filter areas, and to keep the pool surface clean
Position pool jets downward for better circulation
Shock your pool more often if you’re getting frequent rain or if your pool is getting more use than normal
Encourage swimmers to rinse off before getting in the pool

These techniques, especially used in combination, should help keep your pool water clear, healthy, and ready for swimming.

Frequently Asked Questions

How do you clear a cloudy pool fast?

To clear a cloudy pool quickly, first test and balance your water chemistry, especially chlorine, pH, and alkalinity levels. Then, shock the pool to remove contaminants. Run the pump and filter continuously for 24-48 hours to improve circulation. You can also add a pool clarifier to help filter out fine particles or use a flocculant to settle debris for vacuuming. Don’t forget to clean or backwash the filter to maintain optimal performance.

Is It Safe To Swim In A Cloudy Pool?

No. While there are some causes of cloudy water that aren’t immediately harmful or dangerous, it’s impossible to know for sure if you’re dealing with a potentially risky problem or a safe one until you’ve tested the water. Head and neck injuries have could occur by diving into water in which one does not know its depth.

Even if testing rules out problems like an algae bloom or high ammonia, having ‘safe’ problems that cause cloudy water can still allow more bacteria and viruses in your pool water, causing more problems.
Additionally, swimming in cloudy pool water can make it harder to treat the problem, which means more time for additional problems to develop.

Is it safe to swim in a cloudy pool after shocking?

No, it is not safe to swim in a cloudy pool after shocking.

Cloudy water can indicate poor filtration, chemical imbalance, or the presence of contaminants. After shocking, chlorine levels may be too high, and combined with unclear water, it’s difficult to judge water safety. Always wait until the water is clear and chlorine levels return to the recommended range (1–3 ppm for pools) before swimming.

Can Your Pool Surroundings Cause Cloudy Water?

Yes, though this situation is relatively rare. If you’re doing landscaping, getting a lot of pollen in your neighborhood, or live somewhere with dust storms, frequent rains, or where there is a lot of fertilized ground, those things can contribute to cloudy water.

That’s because of dust and debris, plus the risk of mineral and ammonia-rich runoff from fertilized land.

Positioning your pool to avoid the worst runoff, shocking your pool after rain storms, and covering your pool when you know that there is dust or pollen in the air can solve these problems.

Will high chlorine levels, high pH and low alkalinity cause cloudy water?

Yes. Having too much chlorine (or any other chemical) in your pool can cause the pH of your pool water to change too much. High pH (alkaline), high chlorine, and too low alkalinity (low PH) can all make your pool water cloudy.

If you suspect that there might be too much chlorine in your pool it’s important to run a test on the water to check your PH, chlorine levels, and other potential problems.

How Can I Clarify My Pool Water Naturally?

You can create a naturally filtered pool a few different ways, though setting up these pools can be difficult and it is challenging to get the right balance of filtration and pool space. That said, there are also chlorine alternatives for traditional pools that might seem more natural, though all of them involve some amount of chemically interfering with the water.

For example, ozone is a more effective treatment option than chlorine and is odorless. Magnesium treatments, bromine, and even baking soda can all be used to help clarify and maintain pool water as well. UV radiation can also be used in combination with other disinfecting agents to reduce the number of chemicals needed to keep your pool water safe and clear. Copper ionization is the most popular chlorine alternative and would eliminate many of the issues listed above.

Conclusion

There are a lot of ways to keep your pool water clear and safe, but it’s important to make sure you aren’t swimming in even marginally clear water because of the health risks and risk of infections from cloudy water.

Fortunately, a home test kit is usually all you need to diagnose the problem, and you shouldn’t need any new or different chemicals to address 99% of the problems that cause cloudy water in home pools.