Cloudy Pool Water after Shock and Algaecide

Everyone is drawn to the sight of a clear pool, especially during the hot summer months. 

You may have tried to maintain the clear appearance of the pool water for months, and then one morning, as you step out the back door to take a quick dip, you find that the swimming pool looks like a large bowl of milk.

You’re stunned because you just used algaecide to clean the pool a few minutes ago, and now it’s turned cloudy.

What happened? 

Cloudy pool water after shock and algaecide could be a result of chemical imbalances, a faulty filtration system in your pool, or environmental factors, and it can be cleared by balancing the chemical levels, eliminating ammonia, monitoring the pH level or filtering the pool water to get rid of algae remains.

Cloudy Pool Water after Shock and Algaecide

Let’s talk about the different reasons your pool water may be cloudy.

What Causes Cloudy Pool Water after Shock and Algaecide?

Chemical imbalances

A ‘balanced’ pool has acceptable levels of pH, total alkalinity, and Calcium hardness. Altering the levels of any of these will lead to an imbalance.

Sometimes, you may need to dump a massive dose of chlorine in the pool to ‘shock’ it, only to realise later that the pool has turned cloudy. 

This aftershock is a reaction to such treatment.

Why the pool becomes cloudy

  1. Algae remains could make a thin layer of cloud on the pool.
  2. Increase in the hardness of the water as a result of shock and algaecide. Calcium hardness is defined as how hard or soft the pool water is. If the hardness is too low, it will erode metals and plastering in the pool. Too much hardness will permit cloudy water.
  3. Low pH water can cause etching and deterioration of the plaster, grout, stone, concrete, and tiling. These dissolve into the water and create a cloudy look.

Faulty pool filter

The water in your pool is pumped through a filter to remove debris and particles. Problems may ensue when you fail to run the filter for long hours every day, and the system is unable to clean the entire pool sufficiently.

Sometimes, even when you run the filter regularly if it is clogged, has worn out or has broken parts, the appearance of the water in your pool could become cloudy. For example, the skimmer basket. A pool skimmer is one component of its filtration system. Without it, debris will clog the skimmer leading to costly damage to the filtration system.

Environmental factors

The pool may be affected by items around it. Debris from construction, fallen leaves or pollen from plants, changes in the weather, dirt, sweat, and various hair products, skin products plus the makeup used by people could make your pool water cloudy.

It is usually wise to check that the filtration system is working perfectly before taking the following steps to clear the pool.

How to clear cloudy pools

Balance the pool chemical levels

Ugly rust stains and scaly white buildup in your pools are clear indications of calcium hardness and low total alkalinity. You must keep the pool water’s chemical levels within these recommended ranges:

  • Total Alkalinity: 80 – 120 ppm Ideal (60 – 180 ppm Acceptable).
  • pH: 7.4 – 7.6 Ideal (7.2 – 7.8 Acceptable).
  • Calcium Hardness: 200 – 400 ppm Ideal (150 – 800 ppm Acceptable).
  • Cyanuric Acid: 30 – 50 ppm Ideal (10 ppm Minimum).
  • Total Dissolved Solid: 0 – 2500 ppm Ideal for Non-Salt Water Pools.

Before you add any chemical to the water, please be certain that the pool pump is on, as this will cause the chemicals to circulate in the pool.

Follow this order to balance your pool chemicals

  1. First, you adjust the Total Alkalinity
  2. Then, adjust the pH level
  3. Next, you adjust the Calcium Hardness
  4. The final step is to adjust the sanitizer level.

Eliminate ammonia in the pool

Ammonia in a pool is often caused by bacteria. Bacteria in pool water can lead to many types of infections.

Regular shocks can kill the ammonia and clear the cloudy water.

Shocking a pool is done by adding a very large amount of chlorine, so the free chlorine level is within the recommended range based on the size of the pool.

Shocking your pool helps to refresh the water. The pool water will then be sanitized, clean, and safe to use.

Check the pH level of the pool

The pH level of the pool refers to the acid or base level present in the pool water.

You must maintain a balanced pH level, to protect your pool from damage.

Invest in a testing kit. Most pH testing kits come with a chart that you can use to compare, and then determine the pH level of your pool. To do this, you dip a strip of pH tester in the pool’s water and compare the colour that it turns into, with the information on the chart.

You can also use an electric tester instead of the pH strips. Electric testers are more reliable and cheaper in the long run.

Other activities that could help you clear the cloudy pool when you are certain that you’ve checked the pH level, gotten rid of ammonia and filtered the pool water so that there are no algae remains, are…

Rid the pool of resistant algae

Some algae are resistant to chemicals used in pool shocking and an overgrowth of these algae could throw your pool’s chemistry off balance.

One simple step to prevent algae in pool water is to cover the pool. You should also keep your pool water filtering constantly. Use the pool often because swimming stirs up the water and debris, allowing the skimmer to catch more particles.

Chlorine is the best anti-algae treatment, but some forms of algae are more resistant than others, making further treatment necessary. Adding a preventive amount of algaecide to the pool, every week after shocking could do the trick.

You should shock your pool at least once a week. 

As a rule, the more often you use your pool, the more often you are expected to carry out a shock.

Monitor debris in the pool

Debris is unattractive and usually falls to the bottom of the pool where they look unsightly and leave stains.

To manage debris, skim the surface of the water with a net or leaf rake; scrub the walls, steps, below the skimmer and crevices of the pool with a pool brush. 

Do not forget to vacuum the pool, as well.

Frequently Asked Questions (FAQs)

Will rainfall cause my pool to be cloudy?

After a heavy downpour, dust, sand, tree droppings, insects, pollen or acid rain can contaminate your pool. Rainwater is known to have acidic properties which can affect the chemical balance in your pool.

Do cloudy pools sometimes clear on their own?

Sometimes, after shocking the pool, it turns cloudy. This is normal, and within an hour or so the water should be clear again.

 How long is the pool cloudy after shocking?

Usually after a few hours.

What happens if you put too much algaecide in the pool?

This will result in foamy pool water that begins to produce small bubbles. Swimmers experience eye and skin irritations as a result of this. 

 How long does it take a pool to clear after adding algaecide?

It can take a few hours or within 24 hours, depending on how severe the algae outbreak was in the pool.

Is it likely that inviting many people to my pool party can lead to a cloudy pool?

Yes, having a lot of people over to swim in your pool during pool party, can lead to a cloudy pool, but that can be taken care of, so go ahead and enjoy your day.


Well-balanced pool water will ensure that your pool is safe and protected, so you can spend quality time enjoying your pool and less time worrying about the quality of the water in it.

It is easy to balance pool water by sticking to the how-to steps and getting into the habit of doing so regularly. 

The key is to establish a routine and take early action if you notice discolorations, cloudy water, scaling or other signs of trouble, and when you notice cloudy water after shock and algaecide, filter the pool to remove algae remains, check the pH level or get rid of the water completely so you can do a proper cleanup of the pool.

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