How to make the pool water crystal clear

bañarse en una piscina con agua limpia y cristalina


Swimming in pools with crystal clear water is one of the best sensations in this world. If, in addition, the pool water does not irritate our eyes or dry our skin, surely, we would like to become fish to swim in the pool water as long as possible.


However, making the swimming pool water crystal clear can sometimes cause a lot of headaches.


At Gre, with more than 50 years of experience in the manufacturing of aboveground swimming pools, we have solutions for every problem the pool water may have.


But what can happen so that the pool water is no longer crystal clear and how can we make the swimming pool water totally clear and transparent to enjoy our pools both in winter and summer?


The pool water is cloudy


If the pool water is cloudy, this can be due to several causes, such as insufficient filtering, a high pH or an organic waste excess. The solution is to add water treatment chemicals.


In order to give solution to the filtering of the pool, it will be necessary to carry out a backwashing of the filter.


To know if the pH is high, it will be necessary to analyze it to evaluate if it is below 7.2 or above 7.6. In this video you can see how to analyze the pH of swimming pool water more easily with Gre’s pH analyzer.



A much easier option is through Blue Connect or also with the Blue Check strips.

You can raise or lower the pH of the pool:


  • pH regulators. 150 grams are diluted per 10 m3 of water to increase or decrease the pH rate by 0.2 points.


Normally pH regulators are used on a daily basis and are part of the regular maintenance of your pool.

Keeping the pH of  your swimming pool water in perfect conditions will prevent eye irritation and skin dryness, as well as keeping your pool water clean and crystal clear.


In the case of an organic waste excess, it will be necessary to make a shock chlorination and add liquid flocculant to the pool water.


  • Shock chlorination. Remember that normal chlorine values are between 0.4 and 1.4. The forms of chlorine for swimming pool water are:
  1. granulated chlorine to dilute. The quantity will be from 15 to 30 grams per 10 m3 of water.
  2. Chlorine in 20 gram tablets to be placed in the skimmer dispenser. One tablet per 10 m3 of water.


The use of shock chlorine disinfects quickly destroying organisms, fungi and bacteria.

Remember that normal chlorine values are between 0.4 and 1.4.

Normally the shock chlorine is usually used at the beginning of the season or after extreme weather conditions or with intensive use of the pool.

The chlorine will allow the water to be clean and free of possible infections.


  • Liquid flocculant. You will be able to dilute it in the pool water in a proportion of 5 ml for each 10 m3. This will help to eliminate suspended particles.

The flocculant is usually used in the pool maintenance and is an indispensable factor for the pool water to be crystal clear.


The pool water is green


That the pool water is green is for one cause only, algae presence. In spite of the fact that the problem is one, the rapid reproduction of algae in temperate waters will mainly force us to take certain previous steps to eliminate them completely from our pool.


In the first place it will be necessary to clean, brushing the bottom and walls of the pool. To do this, you can do it with a brush for algae or you can avoid spending hours cleaning with the use of a pool cleaner robot like the TornaX.


Subsequently it will be necessary to analyze the pH of the pool water and adjust it between 7.2 and 7.6 and perform a shock chlorination as explained in the previous section.


Then add extra anti-algae. In this case, as it is the extra antialgae, it is necessary to dilute 0.25 ml per 100 m3. This will eliminate the existing algae. The application of extra algae is applied as appropriate whenever we see any algae in the pool water.


And finally add liquid flocculant to the pool according to previous instructions.

The colour of the pool water is brown


The brown colour of the pool water may be due to the presence of iron or manganese.


The solution in this case is exactly the same as for cloudy water.


  • Analyze the pH and adjust it between 7.2 and 7.6.
  • Perform a Shock Chlorination.
  • Add Liquid Flocculant.

Incrustations in the pool vessel

Sometimes, if the water of the pool is too hard, it can cause incrustations in the vessel and bottom of the pool and in the water recirculation filter system. The hardness of the water and how it affects the pool vessel is controlled by keeping the pH and alkalinity correctly adjusted.


A pH value higher than 7.8 promotes incrustations and eliminates the disinfecting power of the chlorine.


It is therefore necessary to adjust the water pH and add an antiscale product as indicated.

Irritated eyes, dry skin and/or bad smells

In order to avoid irritated eyes, dry skin and bad smells in the pool water, the pH of the pool should be analyzed and adjusted and shock chlorination should be performed.


Chemical product for swimming pool water in single doses

Gre’s constant innovation in chemical products for the maintenance and treatment of swimming pool water has led to a new pod or single-dose format.

These pods are much more comfortable, clean, safe and also allow to unify several products in a single dose. With only one application we will achieve all the previous steps.

The current single-dose and pods for swimming pool water treatment are:


  • pH Increaser/Reducer
  • Shock Chlorine
  • Anti algae
  • Flocculan
  • Multiprotect
  • Complet 4 Actions (chlorine + anti algae + stabilizer + flocculant)
  • Winteriser


If you still have problems with the water of your pool, consult the nearest distributor or contact Gre directly to know the chemical product that best solves the problem of your pool.


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  1. Tengo una piscina pequeña y a causa de la lluvia se pudo el agua verde,la tratamos con cloro de choque y después clarifica te el agua está limpia pero el agua no consigo que este cristalina.

  2. Buenos días, le envió un enlace donde puede encontrar útiles consejos sobre como poner el agua de su piscina cristalina, espero le sirva para resolver su problema. Un saludo

  3. Buenos días, puedo poner floculante, con el invernador puesto? Gracias

  4. Hola Miguel,
    nosotros no lo recomendaríamos. Lo mejor es utilizar floculante cuando la filtración de la piscina esté en marcha. En general se utiliza al momento del arranque de la piscina después de la temporada de invierno. Se utiliza también en momentos de mucho viento que han traído impurezas muy pequeña y se necesita floculante para tener el agua mas cristalina.

    Espero haber solucionado tu pregunta.

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