Cloudy Pool Water

Cloudy pool water can happen overnight and when it does it can be difficult and time consuming to diagnose and remedy, but it doesn't need to be. There is nothing more disheartening than going for a swim with family or inviting friends over for a swim only to find that your pool has clouded up unexpectedly. The good news is that there is always an explanation and after reading this page you will have a better understanding why it happens and the best way to fix it fast

cloudy pool water

The goal should always be to first diagnose the problem and fix it with as little chemicals as possible, if they are even necessary in the first place.  As a general rule you should always start using less and never add any product based on a hunch unless you really know your pool.  A lot of pool problems including cloudy water is simply caused by too many chemicals being added to the water over time. 

If your pool sanitization includes a salt water chlorine generator you shouldn't have any different issues than regular chemical chlorine pools and you will most likely experience less chemistry related problems in general. Salt water pools constantly get rid of nasty chloramines and reduce the need for clarifying chemicals. 

Since pool water can become cloudy for many reasons you may need to spend a bit of time up front figuring out what exactly is causing the problem. Keep in mind that every minute you spend learning about your pool will make it easier to maintain and diagnose in the future. Let's take a look at the most common problems that cause clouded water. 

salt water pool maintenance guide

What Causes Cloudy Pool Water?

Every pool is different and it would be impossible and impractical to go over every possible cause of cloudy pool water. We will however go over the most common problems for salt water pool owners and regular pool owners and then we'll go over how to fix and prevent some basic problems that can occur. The most common reasons your swimming pool water is cloudy can be categorized into two main categories; chemistry and sanitation or filtration and circulation.

Pool Chemistry and Sanitation

The number one cause of cloudy pool water is inconsistent chlorination or low free chlorine. If you don't maintain a steady level of free chlorine either by producing it through your chlorine generator, the super chlorinate feature or a chlorine dispenser you could run into all sorts of problems.

It speaks to the importance of purchasing a quality pool test kit so you can keep an eye on your pool's chemistry. It means you won't have to rely on guesswork, inconsistent pool store analysis or low quality strips.  

pool chemistry

The reasons you may be experiencing cloudy pool water related to chemistry:

  1. Inconsistent or inadequate chlorination.
  2. The pool shock was used incorrectly or added simultaneously with calcium chloride. Never add chemicals at the same time, always allow one chemical to dissipate before adding another. 
  3. An overdose of chemical increasers including; alkalinity, pH and calcium.
  4. Langelier Saturation Index is too high. 
  5. Iron or manganese in the water.
  6. An overdoes of stain and scale inhibitors, flocculant or foamy algaecide.
  7. Using minerals or catalysts without sufficient shocking.
  8. Paint, oil, tree sap, dust, rainwater and other environmental contaminants. 
  9. An excess of people, pee, lotion and other biological waste. 
  10. Pool water is more than 5 years old.

Pool Filtration and Circulation

Aside from inconsistent chlorination the most common culprit causing cloudy pool water is pool algae which can be caused by poor sanitation and circulation. If your pool is green and cloudy you can almost be sure that you have an algae issue that needs to be dealt with.  

In addition to living algae you may end up with cloudy water from dead algae that can be very difficult to remove especially if you are using a sand or cartridge filter. It will appear as grey or white cloudiness usually after using an algaecide or shock. 

pool circulation

The most common reasons for cloudy pool water caused by poor filtration and circulation are:

  1. Algae alive or dead.
  2. Pool pump and filter system are not running for long enough intervals.
  3. Pump is creating too much pressure for an undersized filter, usually a sand filter.
  4. The pump is not sized properly and isn't creating enough pressure to filter adequately and complete adequate water turnover.
  5. The pool filter is dirty, blocked, damaged, missing filter media or parts, not set properly, or backwashed improperly.
  6. Plumbing is damaged, blocked, too narrow or a valve is closed off. 

How to Fix Cloudy Pool Water

It isn't always easy to diagnose cloudy pool water but now that you know the most common culprits you can hopefully fix the problem without adding any sanitizer or chemicals. It's also possible that all you need is to increase chlorine production on your chlorine generator or increase the amount of time your system is running throughout the day. The following steps will take you through the next process if you believe your cloudy pool water is related to chemistry or filtration.

1.  Test Pool Water

The very first thing you should do is test your water using a quality pool test kit or take it to a local pool store. It is very common for test strips and even local pool stores to give unreliable test results so it's a good idea to double check. If you are a salt water pool owner we recommend an all in one kit that includes a reliable saline test. The money you spend on a good drop test pool kit is going to be worth every penny down the road. 

2.  Adjust Chemistry 

It's time to look at the results of the test and adjust levels as needed. It's a good time to read through our pool maintenance information to make sure you are within the recommended ranges for; salinity, free chlorine, pH, alkalinity and calcium hardness. After you have everything balanced you can reassess your pool and continue with any of the following methods depending on your pool's chemistry. 


A lack of free available chlorine could be causing the cloudy water, if there is more than 0.3 ppm difference between total available chlorine and free available chlorine it means that you have high chloramines and a shock will be beneficial. A good pool shock will kill chloramines and free up the chlorine in your pool but keep in mind that a shock may temporarily cloud your pool so be sure to keep your filtration running and clean until it has cleared up. 


If you have determined that your pool chemistry is balanced including acceptable free chlorine levels, your next option is to try a pool water clarifier. Pool clarifiers are a coagulant that clumps tiny particles together into bigger particles so they have a better chance of being filtered out. If you use a clarifier keep your filter system running and clean at all times and your filter may require a backwash or cleaning during the process. 


The final basic option for cloudy pool water is to use a flocculant or floc for short. It's a great product if you want to clear your pool fast but it will require some time and effort on your part. It's similar to how a clarifier works by collecting small particles together but instead of them being filtered out, they are so large and heavy that they sink to the bottom of the pool. 

The particles that have collected at the bottom of your pool need to be vacuumed out with your pool vacuum set to "waste" or "backwash". This will avoid passing the debris through your pool filter system where it can get clogged. You want to take it straight from the bottom of the pool and directly out. There will be a lot of water wasted so you will need to add water to your pool before, during or after the process.

Another option is to use a robot pool cleaner that works independently from the pool system. An automatic cleaner will also keep your pool crystal clear by constantly vacuuming out dirt, debris and organisms before they have a chance to multiply. 

3.  Filter System

As you decide which method to use to clear the cloudy pool water, it's important to ensure that your filter system is working properly and stays clean throughout the process. A good working filter system is absolutely key to keeping pool water clear so it's always good practice to keep the filter clean and your system running at least two cycles of 8 hours every day.  

If you still aren't sure what is causing the cloudy pool water you can contact one of our experts that will get back to you within 2-3 business days. Include as much information as possible including details about your pool chemistry, pool size, system, vacuum, etc. 


Please use all appropriate and proper safety precautions when attempting projects on this website. All projects are attempted at the reader's own risk.

Salt Water Pool and Spa™ participates in the Amazon Services LLC Associates Program, as an Amazon Associate we may earn a commission from qualifying purchases. 

SWPS Home Page > Salt Water Pool Maintenance