Why is my pool cloudy after I shocked it? Fixes for a pool that isn’t clear

Discover why a pool can still be murky after shocking and what you can do to make it crystal clear

Swimming pool with deck surround and sun loungers
(Image credit: Getty Images)

Shocking a pool is a necessary part of its maintenance, and a task you’ll need to carry out regularly. But what if you’ve shocked the pool and the water is still cloudy?

If your backyard pool has cloudy water, you shouldn’t swim in it – and it won’t look good either – so knowing why the pool water might still be cloudy, and more importantly how to remedy the problem is essential.

In this guide, we’ve put together the reasons your pool can be cloudy after you’ve shocked it, and what you can do to fix it so family and friends can return to water that’s crystal clear as well as sanitary.

small swimming pool with decking

(Image credit: Caia Image / Collection Mix: Subjects / Getty Images)

6 reasons a pool can be cloudy after you’ve shocked it

Every pool owner has to know how to shock a pool and once you understand the easy steps along with how often to shock a pool you can keep up with this necessary task. If the water’s cloudy after shocking, therefore, it can be a nasty surprise.

Take a look at why a pool can be cloudy after you shocked it and the solutions.

1. You haven’t waited long enough

A cloudy pool doesn’t clear instantly, so the issue can be that you simply haven’t waited long enough for the water to clear. Think two to three days, although it does depend on what caused the cloudy water. You should allow the filtration system time to do its work before you ask why the water it still cloudy.

2. High calcium levels

Calcium can be the culprit if the pool remains cloudy. ‘High calcium levels (calcium hardness) in pool water can lead to cloudiness due to calcium scaling,’ says Hubert Miles, certified pool and spa inspector through NACHI. ‘When you shock a pool, you introduce a high dose of chlorine or other oxidizing agents to eliminate bacteria, algae, and other organic contaminants. However, if the pool water has high calcium levels, the shock treatment can cause calcium to precipitate and form cloudy particles in the water.’

Be sure to keep the calcium hardness level between 200 and 400 parts per million (ppm) to avoid this result.

3. High pH level

One answer to why a pool can still be cloudy after you shocked it is a high pH level. ‘When the water has pH levels above 7.8, the water becomes alkaline, which can result in cloudiness even after shocking,’ explains Hubert Miles.

‘High pH can interfere with the effectiveness of the shock treatment, making it less potent in killing bacteria and algae. Additionally, elevated pH levels can contribute to the precipitation of minerals, leading to cloudiness in the pool water. Some pool shocks, like calcium hypochlorite, have an elevated pH level. Using this type of shock in a pool with an already increased pH level will usually lead to cloudy water problems. If a pool has a high pH level, it can cause calcium buildup and scaling in the pool, in addition to reduced chlorine efficacy and, consequently, cloudy pool water issues.’

Before shocking, check the water chemistry and adjust pH to 7.2 to 7.4 – you can use a pH reducer. Total alkalinity level, meanwhile, should be between 80 and 120 ppm (parts per million) first.

checking the pH levels in a pool

Check to make sure your pool pH is at the correct level

(Image credit: Getty Images)

4. High cyanuric acid level

Cyanuric acid is a useful pool chemical but it could be the cause of cloudiness after shocking. ‘Cyanuric acid, commonly known as a stabilizer or conditioner, is used to protect chlorine from degradation caused by ultraviolet (UV) rays from the sun,’ explains Hubert Miles. 

‘However, excessively high levels of cyanuric acid can hinder the effectiveness of chlorine, leading to insufficient disinfection. This can result in persistent cloudiness even after shocking. Maintaining the cyanuric acid levels within the recommended range is important to ensure proper chlorination and prevent cloudy water.’

5. Contaminants remain

If you shock your pool but the water is still cloudy, and the free chlorine level soon drops too low, then it may have had high levels of contaminants. This might be after a storm and there has been run-off from the surrounding pool area, or when the pool has seen a high level of use, for example after a pool party.

In this case, you may need to repeat the shock treatment more than once to make the water crystal clear again.

6. Filtration problems

As we mentioned above, it’s important to leave the filter to do its job after shocking a pool, and in general, you should allow the pump to run for at least eight hours a day during the swimming season.

Water circulation and filtration problems can, though, be why the pool isn’t clear. ‘After shocking, if the water circulation and filtration system are polluted, the pool water may remain cloudy,’ says Hubert Miles. ‘Insufficient water movement and filtration can fail to remove the particles and contaminants introduced during the shock treatment, leaving the water hazy or cloudy.’

Take a look at the filter manual for instructions on the maintenance you should be carrying out. And call in a pro if necessary.


Is it normal for a pool to be cloudy after shocking?

A pool can temporarily be cloudy after shocking and, as the filter runs, the cloudiness should clear. But be aware that if it doesn’t, there are issues you need to deal with, which might include filtration problems, a high level of contaminants, and a high pH level. Test the water chemistry if the cloudiness remains, and check out the pool equipment as well.

Can too much chlorine make your pool cloudy?

Too much chlorine can make your pool cloudy after shocking but this should prove to be a temporary issue. Unbalanced pool chemistry is more likely to the cause of cloudiness, however. If there have been rainstorms, contaminants can be introduced to the pool while the water that’s been added to the pool water can affect the chemistry.

A cloudy pool can often be a result of the environment. As well as storms, events such as construction nearby can cause contaminants to enter the water. And what’s in the yard affects it too – think pollen in the pool, feathers, and so on. As well as checking pool chemistry and shocking the pool regularly, plus maintaining pool equipment, it’s worth using a pool clarifier regularly to help combat environmental factors.

Sarah Warwick
Contributing Editor

Sarah is a freelance journalist and editor. Previously executive editor of Ideal Home, she’s specialized in interiors, property and gardens for over 20 years, and covers interior design, house design, gardens, and cleaning and organizing a home for H&G. She’s written for websites, including Houzz, Channel 4’s flagship website, 4Homes, and Future’s T3; national newspapers, including The Guardian; and magazines including Future’s Country Homes & Interiors, Homebuilding & Renovating, Period Living, and Style at Home, as well as House Beautiful, Good Homes, Grand Designs, Homes & Antiques, LandLove and The English Home among others. It’s no big surprise that she likes to put what she writes about into practice, and is a serial house renovator.