Cloudy water, milky colour - how to purify

A land flowing with milk and honey... although everyone would like to live in such a place, not everyone would like to have this 'milk' in their pool. Sometimes, however, it happens that the water we have in our pool becomes turbid and turns an unexpected white colour. This is certainly not a 'miracle' of any kind, but a sign that there is something wrong with the water. Fortunately, this is not an insoluble problem and does not involve replacing all the water in the pool.

  • The milky colour and cloudy water is associated with particles floating in the water, forming a suspension of the
  • Turbidity can also be caused by high concentrations of minerals
  • Using coagulants is a recipe for crystal clear water

The pool water is cloudy, milky and smells unpleasant

The milky colour and cloudy water is associated with particles floating in the water, forming a suspension that gives the 'milk' effect. This happens when we neglect to clean the pool. There are too many organic impurities in the water. This is why, in addition, there is an unpleasant smell.

Apparently we used too little disinfectant, hence the symptoms. If we can say with our hand on our heart that we followed the manufacturer's recommendations, take a look at the filter. It is probably dirty because it has not been rinsed regularly.

Whether we have used too little chemistry or the filter has not been properly cleaned the water 'repair' looks the same.

Thoroughly rinse your pool filter:

This point is quite often forgotten by customers, and undoubtedly regular rinsing of the filter, is a guarantee of keeping the bed in good condition and of optimal water flow through the pool filter.

With moderate use of the pool, the filter should be rinsed once every 14 days, and with increased occupancy once every 7 days.



Check the pH of the pool water with a suitable tester.

Adjust the pH to the appropriate level:

Depending on the readings you obtained when measuring the water with the tester, you must now bring the pH of the pool water to a level of 7.0 - 7.4. It is in this range that the chlorine will work optimally achieving its maximum chemical effectiveness.

Of course, to lower the pH of the water, use pH Minus and to raise the pH of the water, use pH Plus accordingly.



Carry out shock chlorination - use shock chlorine:

This procedure is nothing more than a sudden increase in the chlorine content of the water, thanks to which we will eliminate all the micro-organisms that are present in the pool.

So-called 'chlorination' is another way of saying a breaking point, which will give you the effect of crystal-clear pool water.

Procedure (with filtration activated)

  1. Dissolve an appropriate dose of shock chlorine in warm water in a bucket and spread along the pool shoreline
  2. Alternatively, dose granules directly into the skimmer.
  3. Leave filtration on for min. 48 hours
  4. After about 24 hours, test the pool water with a suitable tester or photometer.
  5. Do not use the pool until the target chlorine content of the water approaches 0.6 mg/l
  6. After 48 hours, rinse the pool filter again and start disinfecting with the long-soluble multifunctional tablets.

Apply coagulant in the form of cartridges:

Along with the application of the shock chlorination discussed earlier, include a flocculant in cartridges in the operation as well - this will aid the crystallisation of the water and cause the dirt to clump together in so-called 'clusters' - in other words, it will improve the filtration process.

Note: After the coagulant has been applied, the pool filter will (plan) become dirty more quickly and will need to be rinsed out more quickly.

Nieprzerwanie fifltruj wodę przez 48 godzin, a później ponownie wypłucz filtr

Expert Advises!

The water in the pool is cloudy and the walls are rough

Turbidity and a milky colour are not only signs of cleanliness neglect. Although waterworks strive for the best possible water parameters, the water may be too hard. This is mainly caused by a high concentration of minerals, mainly calcium and magnesium salts. It is these that precipitate out and cause the water to become turbid.

This is easy to recognise, as a rough and craggy deposit appears on the pool walls. This is actually deposited scale. It's not our fault, it's just the water. Fortunately, we are able to change things and make the water clear.

Mechanically remove the dirt with a brush:

Try to manually scrape the deposits off the walls with a brush or hoover before proceeding with the whole procedure.




Thoroughly rinse the pool filter:

With moderate use of the pool, the filter should be rinsed once every 14 days, while with increased occupancy it should be rinsed once every 7 days.


Use a water hardness control agent:

Scale water is 'hard', so use special pool chemicals to soften the water.

If the limescale cannot be removed with a brush and a vacuum cleaner, use a pool cleaner

Adjust the pH to the correct level:

Depending on the readings you obtained when measuring the water with the tester, you now need to bring the pH of the pool water to a level of 7.0 - 7.4. It is in this range that the chlorine will perform optimally obtaining its maximum chemical effectiveness.

Useful products

Coagulation as a source of crystalline water

Crystal-clear water is the goal of every pool owner. The result is achievable if we follow three key principles: filtration, the use of pool chemicals and mechanical cleaning.

Conscientious adherence to the recommendations of chemical manufacturers and high-quality equipment is a guarantee of crystal-clear water, without any signs of turbidity or colour change.

See all products from the pool coagulants and flocculants category

The sand in my filter after using the flock is hard as stone

This is a sign that too much coagulant has been used. Unfortunately, but the situation cannot be saved and a complete replacement of the filter bed remains.

Water became cloudy after using algicide

An overdose of antigloss agent also causes the water to become turbid. Simply discontinue it and the situation will return to normal.

How can you tell if your water is hard?

There are special strip testers that make it easy to check what level of hardness our water has. Some of the photometers also offer this possibility.

FAQ - Questions and answers

Ask a POOLSYSTEM.PL specialist

Team Poolsystem.pl
Tomasz Tomkowicz

Pool Technology Specialist

Thank you for reading our article, if you have more questions or need more specialized help - write to me using the form.