Cloudy Pool Water Causes
Cloudy Pool Water Causes & Prevention

Cloudy Pool Water Causes & Prevention

In order to prevent cloudy water, we will examine what causes cloudy water in the first place.

Cloudy pool water is suspended particulates floating at all levels in the water and not sinking readily to the bottom. The particulates are typically debris caused by the degeneration of organic matter such as leaves and algae. Most pool owners experience this when they open their pools in the spring. However, in some instances during the summer, the water will mysteriously turn cloudy without the presence of this debris. Or so it would seem. 

Check the pH of the water. If it is above 7.6, debris that was otherwise invisible may become visible and appear as cloudy water. The remedy may be as simple as balancing the pH by adding acid to reduce the pH to below 7.6. 

But, most likely, cloudy water is always caused by:

1. Poor filtration is the #1 cause – 80% of the time, old, dirty and damaged filters are the reason for cloudy water. Another cause is not running the filter long enough, or a mismatch in filter and pool size. You should run your filter 16 hours each day. Your filter and pump should be able to replace/recycle the entire volume content of your pool within 8 hours.

Read more about Matching Filters, Pumps & Pool Size >>

Cartridge filters can block up because the filter size is too fine. The system will subsequently slow down and then shut down to protect the pump. When using C-pool & Spa, be aware that the product is very efficient and will clear your pool by fusing debris and passing it through the filter. If the mesh size of the filter is too fine, it will require frequent cleaning. If that happens, replace the filter with a more porous one, or a larger filter may be necessary.

Another cause of cloudy water is torn cartridge filters that allow debris to leak back into the return jets as a cloudy stream. If the return nozzle gushes out cloudy water, replace the torn filter or clean a dirty filter.

If a DE filter is not charged with enough filter elements, cloudy water will result. You can add diatomite directly in the skimmer. CAUTION. Do not add a filter element designed for DE filters to a normal cartridge system.

2. Lack of algaecide – Algae growth is the eternal enemy of outdoor swimming pools. Algae is brought in on bathing suits, or airborne, or dead leaves and organic debris. Algae is feed by nutrients of the nearby fields and airborne phosphates from farming fields. It blooms as the sun rises and responds to light and heat for growth. You need an algaecide to keep algae in check.

If the algae bloom gets ahead of the chlorine (eg) inputted manually or by (salt-water) chlorine generators, the growth and kill cycle of algae will leave the water cloudy. This is because the dead algae are not evacuated as fast as the chlorine is killing the fresh growth algae. C-Pool & Spa was designed to stop the cycle by making the water inhabitable to algae so it doesn’t bloom in the first place.

3. Lack of chlorine – Always test your water to determine if there is enough chlorine. Cloudy water is a sure sign that the chlorine or the pH balance is off. Chlorine will kill algae and bacteria. It is estimated that in the presence of algae infected water, the chlorine will kill most of the algae but may not have enough energy to be 100% effective.

Thus, the diminished efficacy of the chlorine promotes the growth/kill cycle of algae that results in cloudy water. What’s worse, there would not be enough (free) chlorine present to effectively kill all the bacteria. You could super chlorinate the pool, but most people don’t like a chlorine bath. C-Pool & Spa has figured out that by eliminating the algae, it will free up the chlorine demand and that, in turn, will allow a much smaller chlorine content to effectively kill harmful bacteria.


4. Combined chlorine – Another cause of cloudy water is an abundance of combined chlorine. Combined chlorine is the combination of free chlorine and nitrogen. The nitrogen is the result of an aqueous reaction of pollutants such as urine, sweat, suntan lotion, hair spray and perfumes with the pool water.

That “chlorine smell” is, in fact, ammonia gas. Another symptom of combined chlorine is burning eyes. You need an OXIDIZER to reduce the effects of ammonia and therefore eliminate the presence of nitrogen. C-Pool & Spa is an ideal oxidizer because it contains the necessary time tested minerals. Test your water for TOTAL CHLORINE. When the sum of the free and combined chlorine is zero; that is ideal. Therefore, if the combined chlorine is zero, the total chlorine will equal the free chlorine. Get test strips that measure both.

Healthy pool water functions in the cycle of:

1. Filtration

  • Filter backwashed or cleaned
  • Pump basket cleaned
  • Skimmer basket inspected daily and cleaned

2. Circulation  

  • water levels maintained 
  • pump cycle and duration adequate

3. Sanitization

  • Balance pH and chlorine