When your pool looks like a giant bowl of milk—or worse, like the Swamp Thing moved in—no one wants to swim in it. Not only is it uninviting, it could be breeding dangerous bacteria or damaging your pool and circulation system.
To avoid expensive damage and potentially serious illnesses, you need to figure out the cause of your cloudy pool water before you can fix it. Solutions will vary depending on how the water became cloudy in the first place.
Clear Yesterday, Cloudy Pool Water Today. What Happened?
Usually, it takes some time for your pool water to turn cloudy. You may think you notice a bit of cloudiness at first, but it’s easy to blow off. Once it’s undeniably cloudy, you may have a lot of work ahead of you to fix it. Some water problems can cause noticeable cloudiness to occur seemingly overnight.
So what the heck happened to make your water look like milk?
Invasion of the Pool Sanitizer Snatchers
When natural debris like leaves ends up in your pool, your sanitizer gets right to work attacking it. But sanitizers aren’t meant to dissolve large amounts of solids—that’s what your filtration system is for. If the solids aren’t physically removed from the water, by you or your filter, they can gobble up your sanitizer.
Humans also introduce solids to your pool. Sweat, sunscreen, beauty products, and even urine deplete your chlorine. It’s one of the reasons you add sanitizer to your pool in the first place, but it’s also the reason you have to keep adding it.
The sun is another sanitizer thief. Its powerful ultraviolet rays break apart the sanitizing hypochlorite ions created when you add chlorine to your pool, causing them to evaporate into the air around your pool. This means less sanitizer and more dirt in your water.
One more chlorine-hogging pollutant is algae. As long as you have an algae problem, your pool will require a copious amount of chlorine or bromine. Not to mention, you won’t want to swim in it.
When you have contaminants hogging the chlorine, not only will you need to add more sanitizer, your chlorine won’t work as well. So while the chemicals are busy attacking a pile of rotting leaves on the floor of your pool, they’re less effective at quickly killing hazardous pool water pathogens and bacteria, such as E. coli, making your cloudy pool water both ugly and dangerous.
Your Pool’s Circulation System
Problems with your pool’s circulation system are a leading cause of cloudy, hazardous pool water. It’s mostly preventable by keeping your pool circulation system healthy.
When everything is working correctly, and you’re running your filtration system at least eight hours per day, you should see minimal debris in your water. All sorts of contaminants will be removed from your pool by your filter and sanitizer working together.
Your pool circulation system can fail you as it gets older, or it can be damaged by wonky chemical levels or neglect. When your filter can’t remove contaminants as well as it should, you get cloudy pool water, and probably a handful of other gross water problems.
When Will I Ever Need to Know Chemistry After High School?
Maybe you’re lucky and naturally gifted when it comes to chemistry. Maybe you’re like a lot of folks and even basic pool chemistry is confusing to you. If you don’t have a good grasp on how to keep your pool water balanced, it’s just a matter of time before you wake up to a cloudy pool.
Cloudiness may even be one of the less concerning problems that imbalanced water can cause. More serious issues resulting from yucky water include stained pool walls and corrosion of pool accessories and components.
No matter your level of comfort with ions and compounds, take just a week or two off from balancing your pool chemistry and your water could become a cloudy mess.
Alternatively, high pH, high alkalinity, high calcium hardness, and even too much sanitizer can cause cloudiness. Adding chlorine shock to an otherwise perfectly clean and balanced pool can even cause temporary cloudiness.
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Cloudy Pool Water Looks Gross, But So What?
You know the possible reasons why your pool is cloudy, but is it really a big deal? Well, yeah, cloudiness is really just one symptom of bigger problems in your water.
High Bacteria Levels
Chlorine (or bromine) serves a vital role in keeping your pool water clear and healthy. The dangerous aspects of a lack of sanitizer—whatever the cause—include bacteria growth and increased stress on your filter.
When sanitizer levels are low, bacteria survives in the water for longer periods. Swimmers may be exposed to dangerous contaminants, such as E. coli and Legionella.
Low Filtration Efficiency
A clogged filter, dying pump, or simply not running your filtration system for at least eight hours a day can cause cloudy pool water. If all of your water isn’t being run through a fully functioning, clean filter it can retain debris, leaving you with cloudy pool water.
Your sanitizer will get used up more quickly. Your pump may have to work extra hard and whatever water does make it through to your filter may not be well distributed by the pressure side of your circulation system.
All of this results in dirty-looking water, while also contributing to bacteria problems that can endanger the health of everyone who uses your pool.
Scaling, Pitting, and Clogging
You’ll face myriad problems if your water chemistry is out of whack. High pH means your water is less acidic than it should be. The soft water tends to form scale on pool surfaces and inside plumbing while making it more difficult for your sanitizer to work. This can cause filtration problems, bacteria growth, and cloudiness.
Highly alkaline pool water will also form scale, plus it won’t help stabilize your pH the way it should. Both high pH and high alkalinity can lead to pitting in metals and wear and tear on vinyl, despite not being acidic. Too much calcium creates flaky buildup, clouding your water and clogging your filters.
Finally, high levels of chlorine can cause skin and lung irritation, especially if you have asthma or other breathing difficulties. If chlorine levels are wonky, you can also end up with a lot of chloramines—the byproduct of chlorine sanitizing—which can be irritating and even corrosive.
Dangerous Swimming Conditions
Cloudy pool water is just the tip of the iceberg if you’ve got an algae bloom. While the types of algae found in your pool aren’t particularly hazardous to your health, like the algae found in the wild can be, it can be physically dangerous to swimmers.
With algae, your pool water can become so full of suspended debris, it’s impossible to see through the water. That degree of cloudiness is a drowning hazard because you won’t be able to see if someone has fallen in or if a swimmer is struggling underwater.
Until you’ve cleared up your pool water, don’t allow anyone to swim in it. Make sure small children and animals can’t find their way into your pool area either—an important consideration at all times, not just when the water’s cloudy.
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Make Your Cloudy Pool Water Turn Crystal Clear
Ready to get your pool water back to its former crystal clear glory? It’ll take a little hard work, but you’ve got this—and we’ve got you!
Deep Clean
Before you do anything else, start by giving your pool a good scrub down. Remove large debris with a heavy-duty skimmer If you click this link and make a purchase, we earn a commission at no additional cost to you. . Brush your walls well with a stiff pool brush If you click this link and make a purchase, we earn a commission at no additional cost to you. , then vacuum.
If you think you’ve got an algae problem, vacuum to waste.
Shock It
To get rid of all the gross and dangerous crud in your cloudy pool water, shock your pool. This mega-dose of chlorine (or non-chlorine shock for pools that use other sanitizers) will eliminate cloudiness caused by bacteria, organic contaminants, and algae.
Note: If your cloudy water is due to pool algae, you’ll have to double or triple shock depending on the type of algae that’s invaded your pool.
Filter Forever
Okay, you don’t actually need to filter your pool water indefinitely. Eight hours per day is enough for most pool pumps to turn over the average backyard pool. But you’ll definitely want to deep clean your sand or D.E. filter with a filter cleaner If you click this link and make a purchase, we earn a commission at no additional cost to you. . If you have a cartridge filter, replace your cartridge before running it.
Do this after you shock the pool to be sure the extra sanitizer is rinsed through your circulation system and filter, and clean water is distributed.
GLB Pool & Spa Products Pool Filter Rinse - 1 qt. Price: $22.90 
Use Your Bottom Drains
The main skimmer is at the surface of your pool. It can’t get to the debris at the bottom. Even some pool vacuums can’t get quite all the sediment away. If you turn on the bottom drains in your inground pool, you’ll be sucking that sediment straight to your filter.
Do you have an above ground pool that doesn’t have bottom drains? Use this trick: Hook up your manual vacuum cleaner and center it at the bottom of your pool. Then turn it upside down. Your filter will pull water from the bottom of your pool, then release the filtered water through the return jet.
Balance Your Chemistry
Once you’re sure your water is as clean as it can be, test it or take a sample to your local pool store. Adjust chemicals as needed until your water is balanced. Use chlorine stabilizer If you click this link and make a purchase, we earn a commission at no additional cost to you. —also called cyanuric acid—to protect your chlorine levels.
Taylor Technologies Complete Test Kit Price: $59.99 
Floc Your Pool
If you’re in a hurry and your cloudiness isn’t too bad, you can try using a pool flocculant (a.k.a pool floc). Once the floc If you click this link and make a purchase, we earn a commission at no additional cost to you. does its job, all the suspended debris in your water will sink to the bottom. Vacuum it out (to waste), top off and balance your water, and you’re all set to use your pool.
In The Swim Super Floc Out Pool Water Clarifier - 1 qt. Price: $23.99 
Use Pool Water Clarifier
You can make this pool additive a part of your weekly water care routine as a preventive measure. Pool Water Clarifier If you click this link and make a purchase, we earn a commission at no additional cost to you. won’t address any of the more serious problems that may cause cloudy pool water, but it will help keep your otherwise well-maintained pool water looking great by coagulating debris making it easier for your filter to catch.
HTH Super Concentrated Pool Water Clarifier - 1 qt. Price: $32.59 
Stop Cloudy Pool Water Before It Starts
Clearing up your pool isn’t a massive undertaking, but depending on the problem it can cost you a bit in chemicals and elbow grease. One of the best pieces of advice we can give you to protect your pool from water problems is to create and stick to a pool maintenance schedule.
Make sure the only clouds you see are the ones in the sky. Weekly testing and balancing, skimming and vacuuming, basic filter maintenance, and regular shocking will keep your pool healthy and clear all season long.
Happy Swimming!
Frustrated by adding chemicals and trying to keep your pool clear all the time?
We cut out all the confusion of pool maintenance in this easy-to-read illustrated ebook and video course. It'll help you save $100 right away on pool care!
Click here to learn moreRecommended Reading What You Should Do to Your Pool After it Rains
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