Cloudy Pool Water – An Ultimate Guide To All The Reasons Why

Last Updated on March 28, 2021

Cloudy pool water is a pool owner’s nightmare. It’s uninviting and makes your swimming pool unsafe to swim on. If you’ve owned your pool for quite some time now, you might have experienced cloudy water at least once or twice already.

And much like any other pool issue that you might have encountered before, it’s better to identify the root cause of the problem first before working on a solution.

What Causes Cloudy Pool Water?

Pool experts have agreed that most of the time cloudy pools are caused by one or more of the following reasons:

  • Improper chlorine levels
  • High calcium hardness levels
  • Clogged filter system
  • Improper pH level
  • Improper alkalinity level
  • High ammonia level
  • Algae
  • Debris

Everything near or around your pool can turn your once clean and pristine water into murky water. From the trees to the birds, people, and pool equipment, all these can affect your water chemistry and make your pool water cloudy and unsafe to swim on.

Bad Environment

Are there trees around your pool area? How about wild animals? Or even worse, a construction site?

All these can cause cloudy pool water since they can add debris or dirt into your swimming pool.

Poor Water Chemistry

Whether it’s your chlorine levels, alkalinity level, calcium hardness level, or pH level, a pool can become cloudy if just one of those are not in their proper levels.

Chlorine kills off bacteria, viruses, and micro-organisms that can cause your pool water to become opaque. The suggested amount of free chlorine is between 2.0 and 4.0 parts per million (ppm). You must remember that chlorine levels can be affected by the sun and any organic waste such as your sweat or sunscreen.

When there is an imbalance in your pool’s pH level, it makes the free chlorine ineffective. This imbalance cause chloramine to form and when combined with chlorine result in a cloudy pool water. A pool’s pH level should be kept between 7.2 to 7.8.

You also have to consider your pool’s total alkalinity level which acts as a buffer for your pool water’s pH. Total alkalinity should be maintained at 80 to 120 ppm.

Water with high amounts of calcium in it can also cause cloudy water, however, low calcium levels may cause corrosion and damage your pool structure and equipment. It’s best to maintain the calcium hardness in your pool at 150 to 400 ppm.

Sometimes you can also experience cloudy pool water after you put in some pool shock. This is common and should dissipate over time. You just need to keep your filter running and it should clear up.

Faulty Pool Filter

The pool filter and pool pump need to run for a specific number of hours per day to do their job properly. It’s recommended that you at least run them for eight hours to circulate the water in your swimming pool.

There are three types of filters used in swimming pools:

  1. Diatomaceous Earth or DE Filter
  2. Cartridge Filter
  3. Sand Filter

Among those, sand filters are the most suspect to cloudy or dirty water because of their small filtration surface area. However, all of these filters can be clogged making them inefficient in filtering your pool water.

When the filter is not running or clogged, water becomes stagnant and may cause debris to build up, making your pool water look murky. In fact, problems with your pool’s circulation system are the leading cause of cloudy pool water.

You also need to check for your filter media if it needs to be replaced or cleaned. Sand filters need their sand to be replaced every 5 to 7 years. Meanwhile, cartridge filters need filter replacement every 3 to 5 years. Diatomaceous earth filters, similar to sand filters, need to be backwashed every month and you must replace the wasted D.E. with new ones.

Always remember that when your pool filter system can’t remove contaminants, you are left with cloudy pool water, and probably a handful of other pool problems.

Different Solutions To Cloudy Pool Water

Since cloudy water can be caused by a variety of reasons, we’ve identified the different solutions you can implement to get your pool back to its normal conditions so you and your family can swim on it again.

How to Clear Cloudy Pool Water Caused by Low Free Chlorine

Pools can have low free chlorine levels if there is an improper chemical balance that may be caused by too high or too low pH, alkalinity, calcium hardness, or stabilizer levels.

The solution here is to not allow chlorine concentration in your pool to get too high or too low. You should be testing your pool water to ensure it doesn’t deviate from the suggested chlorine concentration of 2 to 4 ppm.

If you need to lower down your pH or Alkalinity, you might use one of the following products.

If you’re facing high calcium hardness, you can use Doheny’s Calcium Reducer to effectively reduce the calcium hardness level in your swimming pool.

Doheny's Calcium Reducer (1 Qt.)
  • Perfect Pool Water Includes The Proper Hardness Levels!
  • Quickly Reduces Hardness Levels
  • Helps Increase Effectiveness Of Your Other Pool Chemicals
  • Contains Phosphonic Acid Derivatives

How to Clear Cloudy Pool Water Caused by Pool’s Surroundings

The dust, leaves, and pollen going into your swimming pool water can build up in your filter and impede its filtering capabilities. Animals, people, and plants can bring in minerals such as nitrates, phosphates, silicates, and sulfates into your pool that may make your water cloudy.

The best way to fix this is by moving your pool to a different and better location if possible. If not, then you can use a pool cover to protect your pool from elements when it is not in use.

How to Clear Cloudy Pool Water Caused by Pool Filter

Your pool filter is vital in keeping your pool water clean and clear. If your filter is not functioning well or is turned off, then the water in your pool becomes stagnant. This will allow the debris and dirt to build up and cause your swimming pool water to change its appearance.

If you checked the chlorine levels and everything looks good and there are no other issues with your current water chemistry, the next thing you should look into is your pool’s pump and filtration system.

Check if any of the baskets or your skimmer is clogged with debris. Make sure that you clean out your pool pumps and skimmer baskets thoroughly, and check the pressure gauge on the filter of your swimming pool.

If you see that the pressure reads 8-10 PSI higher than its starting pressure, your pool’s filter needs to be cleaned, have the media replaced, or backwashed.

How to Clear Cloudy Pool Water Caused by Weather

Heavy rains can make your pool cloudy, sometimes it can even cause your pool to be green.

For this reason, we highly suggest checking the weather forecasts during pool season as a precaution. If there’s a good chance that it will rain in your area, it’s best to have your pool covered with a good quality pool cover.

Excessive rainwater will dilute the balanced pool chemistry. If the water looks cloudy after the rain, you should test the chlorine, pH, and other chemical levels with a test kit, then adjust as needed.

If it stays that way after you re-balanced your water chemistry, you might need to shock your pool to kill all microorganisms in it, especially pool algae.

How to Clear Cloudy Pool Water Caused by Algae

Experts warn that the early stages of algae can cause cloudy swimming pools. Pool algae might not be that obvious when it’s just starting to bloom in your pool, so the best course of action is to test your pool water as soon as you suspect that algae may be causing your cloudy pool water.

As mentioned above, the best way to stop algae from being a major problem is to shock your pool. It’s suggested that you continue scrubbing your pool surfaces when you’re shocking your pool so you can completely remove all the algae.

Your pump and filter are now tasked to start clearing your water. You must continually run your filtration system to trap the dead algae and clean your pool water.

If you’re using a sand filter, you might need to add diatomaceous earth or D.E. to your sand filter to catch very fine particles better.

Best Ways To Clear Cloudy Pool Water

If you’re unable to identify the root cause of having cloudy water in your pool, then you can use the following steps to solve it.

Test Pool Water Chemistry

A good testing kit allows you to measure a variety of factors that affect the quality of the water in your pool. You should already know that high pH, high alkalinity, or high calcium hardness can cause your water to be murky or cloudy.

It’s best to test the water in the early morning right before the sun has the chance to burn the existing chlorine in your swimming pool. If you see that there is a problem with the chlorine, pH, or other water chemical levels, you can adjust those levels accordingly and solve your cloudy water problem.

You can make use of the following pool chemicals to easily balance your water chemistry.

Use A Pool Flocculant

If you would like to use your pool right away, you can utilize a pool flocculant to fix your pool’s cloudy appearance.

A pool flocculant works by gathering all the debris, dirt, and other particles in your pool and sending them to the bottom of your pool. This allows a huge grayish cloud on your pool floor to form.

Since they are on the bottom of your pool area, your filter cannot get to them. You must manually vacuum all those debris out of your pool using your pool pump. If you have a variable pump, you need to change its filter settings to waste or backwash to make sure that those won’t go to your filter or return to your swimming pool.

Warning: You should not use an automatic pool cleaner since that won’t be able to vacuum that cloud of dirt efficiently and may cause them to spread again.

You might lose a lot of water in your pool, so it’s best to have your garden hose ready to add more water to it.

This can be a tedious process and you may waste a lot of water, but using a pool flocculant can clear your swimming pool in about 24 hours if done properly.

Use Pool Water Clarifier

Pool water clarifiers are more like preventive measures than cloudy water solutions. Using a water clarifier may not address the more serious problems that may cause your swimming pool to look cloudy but it can help maintain your pool’s clarity by coagulating the debris in it and make it easier for your filter system to catch it.

When you add a pool clarifier to cloudy water, all the tiny particles clump together into bigger particles so your filter can capture and keep them from re-entering your pool.

Some pool owners recommend using pool clarifiers if you are just experiencing mild cloudiness, so you won’t have to remove water out of your pool. Now once the clarifier has worked, all those clumped particles will be in your pool filter, so you will need to thoroughly clean your filter so it can function properly.

Regular Pool Maintenance

Proper pool maintenance will not only prevent your water from becoming cloudy but also ensures that your pool water is clean and safe for everyone to use.

You can come up with a weekly pool maintenance schedule to monitor the quality of your pool.

This includes performing the following steps at least once a week.

  • Test your chlorine, pH, and alkalinity levels
  • Brushing your pool surfaces with a good pool brush
  • Removing large pieces of debris out of your swimming pool
  • Checking your pool filter and cleaning it if necessary
  • Vacuuming your pool to remove all organic particles in it
  • Shocking your pool

Never underestimate what a good deep clean can do to the quality of your pool water. Giving your pool a good scrub, removing all the debris you can see, and vacuuming it with either a reliable robotic pool cleaner or manual pool vacuum can save you from dealing with a cloudy pool.

How Long Does it Take For a Cloudy Pool to Clear?

The amount of time it takes to clear a cloudy pool can depend on several factors like your pool size, pool location, and how cloudy your water really is. It might take a day or two to clear your pool water.

Some may take more than that though. You just have to run your filter system all day long, keep a well-balanced water chemistry, and add the proper amount of pool water clarifier every other day until the cloudy appearance is gone.

Dealing with cloudy pool water can be a very tedious process, so it’s best to prevent it before it happens. Doing so can save you a lot of time and money, so make sure that you maintain your pool properly.

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