The pool water stays clean thanks to disinfectants, but beginners still find that the water in the pool, even with chemicals like chlorine, becomes milky. What causes milky pool water, and how do you get the water in the pool clear?
The pool becomes milky if the filter system runs for less than 6 hours/day, if there is a lack of disinfectants or if the pool is over-saturated with organic particles. If the pH level is above 7.6, lime forms in the pool water, making it milky.
I will explain why the pool water becomes milky, how to get the problem under control quickly, and which measures can prevent the pool from becoming cloudy.
Clean milky pool water
Milky pool water often happens because of a poor water balance.
The problem can be resolved quickly, but how to clear the milky pool water?
The rough procedure for pool care contains three steps:
- Test of the parameters in the pool.
- Balancing the water using pool chemicals.
- Let the filter system run.
It is not always necessary to go through all the steps to get the pool water clear again.
Sometimes, it is enough to extend the filter run times.
In the following chapters, you will find detailed instructions against milky pool water.
1. Test the parameters in the pool water
Before you dump any multi-cleaner in your pool, the actual parameters should be tested with the help of water testers.
Use a water tester to check that there are enough disinfectants (chlorine, bromine, active oxygen, biguanide) in the pool.
For chlorine, you can use the following table as a guide.
|Free chlorine||0.4 ppm|
|Combined chlorine||0.2 ppm|
|Total chlorine||0.3 – 1.5 ppm|
There is probably not enough free chlorine in your pool, and the pool water turns milky in color.
Attention: We are not correcting the chlorine level yet. We only test whether the disinfection of the pool is guaranteed.
Test the pool water 1 to 2 times a week – ideally with an electronic water tester.
2. Establish an ideal water balance in the pool
Test whether the pH level, the acid capacity (alkalinity), and the calcium hardness are in the ideal range.
If necessary, optimize the levels first before you move on.
Stick to the following target levels:
|Alkalinity||80 – 120 ppm|
|pH value||7.2 – 7.6|
|Calcium hardness||200 – 400 ppm|
First, you must correct the alkalinity in your pool – also known as acid capacity or TA value – as this is related to the pH level.
Therefore, this agent should not be missing in any pool chemistry set.
Then you use a pool chemical to bring the pH level between 7.2 – 7.6. The ideal pH level is 7.4.
Is the pH too high? In this case, use a pH minus.
To lower the pH level in the pool by 0.1, you need 100 grams of pH-Minus granulate per 10 m³ of pool water. In a 50 m³ pool, that would be 500 g.
In my instructions, I explain exactly how to lower a pH level in the pool.
High pH leads to limescale formation in the swimming pool and milky pool water.
With a pH+, on the other hand, you can increase the pH level. This is often necessary after a rain shower.
The pH level increases by 0.1 if 100 grams of pH-Plus granules are used per 10 m³ of pool water.
I have also written detailed instructions for this on the blog – raise the pH level in the pool.
Both the pH plus and the pH minus are part of the basic pool equipment.
Don’t forget to optimize the calcium hardness, as these three parameters (alkalinity, pH level, and calcium) influence each other.
3. Add disinfectants against milky water in the pool
When the water balance is established, stabilized chlorine (di-chlorine or tri-chlorine) or an alternative disinfectant is added to the pool.
Make sure that you don’t use chlorine with active oxygen or biguanides.
These chemicals cannot be combined! Otherwise, the effects cancel each other out.
The result would be milky water in the pool due to a lack of disinfection.
Then a flocculant is used in the pool to improve the filtration.
I would always use the flocculant because it significantly improves filtration.
As always, you can read how this works in my blog.
Info: We don’t shock our pool. This is only a restoration of normal water balance in the pool.
But it can’t hurt to shock your pool if the pool water has been milky for a long time. Read my helpful guide to find out exactly how to do this.
4. Let the pool filter system run
Let the filter system run until the water clears again – usually 24 to 36 hours.
Tip: If the pool water turns light white and threatens to tip over, it is recommended to let the pool pump run for 8 to 12 hours – provided the water balance is correct.
As you can see, you don’t have to shock your pool in the case of milky and cloudy pool water.
If the swimming pool does not become clear on the first run, I recommend the procedure against cloudy pool water with the help of a pool shock in the third step.
How long does it take for the pool to clear?
Your swimming pool didn’t get dirty overnight.
Much more, organic waste has built up in the pool over time, and the water has become milky.
This is why you will not get the pool water clear again within 1 hour.
But how long does it take to clean milky pool water?
- If the pool is slightly milky, the pool can be cleared again within 8 to 12 hours through filtration.
- Using a pool shock, the waiting time – until you can go back into the pool – is extended to 24 hours.
- It can even take up to 36 hours for the pool to clear again in some cases.
So be patient when cleaning milky pool water, and don’t despair if the pool doesn’t clear immediately.
Just make sure that the filter system runs for 24 hours and that the water parameters are correct, then nothing can go wrong.
If you hurry and want to hold a pool party, you can try the following clarifier for the swimming pool.
Important: The filter system must run during this time.
Please note that a pool clarifier is only a temporary solution. Later the milky pool water must be maintained entirely.
If the water in the swimming pool is only treated quickly with clarifiers, there is a risk of long-term consequences that are much more difficult to eliminate.
Even if it takes a little longer, I always recommend my step-by-step instructions against milky water in the pool.
Causes of milky water in the pool
The milky and cloudy pool is not only a visual problem, but in the worst case, it can also lead to illness and expensive repair costs.
That is why it is important to act immediately.
I explained how to clear the milky swimming water, but you should also know the exact causes as a pool owner.
The reasons why the pool becomes milky:
- Too little disinfectant is used in the pool or incorrectly dosed.
- The filter run times are too short.
- An incorrect calcium level causes limescale in the water.
- Too many fine organic particles float in the water.
In the following chapters, I will go into more detail about every single problem – that makes the pool milky white – and explain practical solutions.
1. Bad use of disinfectants in the swimming pool
The inefficient use of disinfectants in swimming pools is usually the main reason the pool water becomes milky and cloudy.
A lack always occurs when too little or too much of a certain pool cleaner is used in the pool.
- In relation to the pool volume, too little chlorine, bromine, active oxygen, or similar is used in the pool, and the organic content in the water increases.
- The chlorine dosage is far above the recommended limit of 1.5 ppm.
- The chlorine is used but quickly loses its effect as no cyanuric acid is used in the pool as a chlorine stabilizer.
But the wrong combination of different chemicals can also lead to white water in the pool.
- Chlorine is combined with active oxygen, which cancels each other out.
- Biguanides cannot be used in combination with chlorine either.
- A phosphate remover is used, which negates the effect of the metal remover.
With a regular water balance test, these problems can be found quickly and resolved in a targeted manner.
That is why water test strips belong in every pool equipment.
The problems with pool chemistry can be many and are beyond the scope of this article.
It is best to read my blog article about pool chemicals and how to use them.
2. Short filter run times lead to milky water
In addition to the optimal use of pool chemicals, the filter run times are essential for a clear pool.
It is of no use if the pool water has become milky and you use active oxygen without paying attention to the filtration.
- The filter running time in the pool is too short if the filter system is running for less than 6 hours/day.
- The filter runs for 6 to 12 hours per day, but the filter system is too weak in relation to the pool size – check the performance of the pool pump using my calculation formula.
- After the pool shock, the pool is still milky because the filter does not run for 24 to 36 hours.
The pool water can become white and cloudy if the filter system is too old and has become weaker over time.
Or maybe you need to replace the sand in the sand filter or a cracked pipe in the system.
Tip: If the pool water is milky and there is a lot of sand in the pool, then the sand filter system is the cause.
In my blog post, I explain how to repair a sand filter and how to remove the sand in the pool.
3. A lot of calcium in the pool water
I have already mentioned the bad use of pool chemicals as a reason for cloudiness in pool water.
But, one thing that is directly related to milky pool water and needs to be explained in more detail is the build-up of calcium in the pool.
If the pool water contains too much calcium, the pool gets a milky color.
But how does limescale form in your pool?
Limescale in pool water always occurs when the potential of the hydrogen is too high (a high pH level).
This is one reason why the pool water becomes milky after using too much of the pH-Plus agent.
In my other blog post, I describe how to lower the calcium level in the pool.
But how can it happen that you stick to the exact dosage and still somehow use too much of the pH plus in the swimming pool?
- This is because the parameter was measured with bad test strips, and you added the pH increaser on the basis of the wrong data.
- You are using a poor quality pH+ and are dosing the product on the basis of incorrect recommendations.
Measure the pH level 1 to 2 times a week and ensure that the pH is at the optimum.
I recommend the remedy shown here to lower a pH level that is too high.
The pH level is raised by 0.1 if you use 100 grams of pH-Plus granules per 10 m³ of pool water. In a 50 m³ pool, this corresponds to 500 g.
In a balanced swimming pool, the ideal pH is between 7.2 and 7.6.
If the pH rises above the ideal level, the oxidizing power of the chlorine or bromine also falls.
The result: The organic level in the pool increases, and the pool water becomes milky.
However, before you optimize the pH level, you should test the alkalinity and, if necessary, adjust it first. I explained how to do this in the linked article above on pool chemistry.
Tip: Pool water that is too warm promotes the build-up of limescale in the pool over a longer time.
I’ll show you how to cool your pool in summer. Follow the link to read my instructions.
Points 1 to 3 explain the most common reasons why the water in your pool turns white.
These points can also be responsible for the pool becoming cloudy.
4. Over-saturation of the pool water with fine dirt particles
White particles floating in the swimming pool or hot tub are able to color the pool water white.
But this is a process that takes a long time.
These so-called floating particles are also known as colloidal soiling.
Don’t worry: The fine particles cloud the pool water but are harmless to you and other bathers.
The white particles in suspension are organic residues such as pollen, perfumes, sun creams, urine, or sweat.
These dirt particles are a food source for algae and bacteria.
You already know what can happen – the pool will be white and cloudy.
A flocculant can help filter the suspended particles, but too much of the flocculant can do the opposite.
Did you guess it?
Exactly, white and cloudy pool water is guaranteed.
Further up in the instructions, I explain exactly how to clean milky pool water and how all the pool cleaners mentioned here can be used optimally.
Tip: If the pool is not only milky white but has other discolorations (brown, black, or light green), then it is very likely that the pool water is cloudy due to metal or algae.
Prevent milky water in the swimming pool
With professional pool care and simple means, you can prevent your pool from becoming milky.
This includes the following steps:
The most common disinfection is done with stabilized chlorine granulate.
- Increase filter runtimes: Check the filter runtimes in your pool. The system should run 6 to 8 hours a day. Is the pump powerful enough for the pool volume to filter the water within this time?
- Cleaning the water surface: Remove dirt from the water surface with a skimmer and do not provide the algae and bacteria with a food base.
- Vacuum the pool floor: If dirt should land on the floor, use a pool vacuum to vacuum the dirt – with a pool cover, you minimize the dirt in the pool.
- Use clarifier: You can use a clarifier for your weekly pool maintenance. The agents are highly concentrated and remove fine floating particles from the pool.
- Measure water values regularly: You should keep an eye on the water parameters at all times. Do a water test 1-2x times a week and add disinfectants to your pool if necessary.
It doesn’t take much to keep the pool or hot tub from getting dirty.
Since pool care is time-consuming and requires large amounts of pool chemicals, getting a pool clear can be quite expensive.
Follow my tips, and you will reduce your pool maintenance costs in the long run.
Do you have any further questions about milky pool water?
Contact me at @contactswimfool on Twitter, Facebook, Pinterest, and all other popular social media – I’ll be happy to help.
Have fun cleaning milky pool water.