How to raise or lower the pH of the pool water

boy before enter to the swimming pool

The pH of the water in the swimming pools is a very important parameter to be able to swim in safety and enjoy a clean water.  It plays an important role in the care and maintenance of swimming pools.  Regardless of the type of pool, its size or model, the pH is an important parameter to enjoy a crystal-clear water.


It’s necessary to maintain the water of the pools in optimal conditions and prevent abnormal levels of pH, too low or too high.  That way, we are sure, also, to extend the life of our pool.


In this article we’ll explain all you need to know to maintain the water of the pool clean, even if it could be summarized in a frequent control of the water with various maintenance products.  The pH of the water and the chlorine are the key factors for the water to be in optimal conditions for bathing.


What is the pH of the water?

The pH, meaning potential of Hydrogen, indicates the level of acidity or alkalinity of the water in swimming pools.

The values for a neutral pH in the pool water are between 7.2 and 7.6.

Maintain the pH in between those values to prevent skin and eye irritation as well as any damage to the pool equipment.


If the pH goes below 7.2, we are then talking of an acid pH.  In those values the chlorine disappears and the bather could suffer many problems: irritation of the eyes and nose, redness of the skin amongst other effects.  But it doesn’t affect only the bathers; the installations of the pool are also facing consequences because materials of the pool, like the liner could be damaged by the acidity.  This could be corrected by adding sodium or other chemicals to re-establish a balance.


On the opposite, when the levels of pH are above 7.6, we talk of an alkaline pH.  If we bathe in a high pH, our body also suffers problems like irritation and dryness, but the water is the worst part.  The chlorine looses its efficiency, the water becomes turbid and algae may appear.  An elevated pH favours the formation of lime deposits in the pool, which also affects pipes and pool equipment.


Why does the pH fluctuate?

The fluctuation of the pH of the pool water can have many causes, including:


  • Sunlight accelerates the dissolution of chlorine, increasing the pH.
  • Wind favours the evaporation of the water, which also increases the pH.
  • The bathers.  The contact of the skin with the water makes the pH vary: with the lotions, creams, dead skin, hair, sweat, and so on.
  • And the method used to add chlorine to the water.


Each pool is different and the people enjoying it too.  We should reach the perfect pH and chlorine balance to be able to fully enjoy the pool in absolute security.


How can I maintain a neutral pH in the pool water?


To know if the water of the pool has a neutral pH, we have to analyse some basic parameters of the water and see if the chemicals are properly balanced.


You can watch an instruction video showing how we can analyse the pH of the pool water with the test kit from Gre.



There are many types of analysing kits in the market.  Some are numeric, more convenient and easy to use like the Blue Connect from Gre, which measures the principal parameters of the water: pH, temperature, disinfectant level and conductivity.


There are also other numeric solutions, like Aquacheck, that measures the chlorine / bromine levels + pH, using True Test test strips.


Besides the facility of use of the digital test machines, we can also find other simpler and more economical options, like the manual test kits.


Those test kits can also be for chlorine / bromine + pH, chlorine +pH, or oxygen / bromine + pH; we can find them in various presentations: in test strips, tablets or drops.


If the analysis of the pool water reveals that the pH isn’t neutral, we must correct it.  If the pH is too elevated, we must use a pH reducer.  If the pH is too low, we must use a pH increaser.


To ensure that the water in the pools is crystal-clear we must check the chlorine levels. Chlorine, being a gas, evaporates; therefore, it is necessary to replace it regularly in the necessary amount depending on the size of our pool. Chlorine is the most used chemical disinfectant for the maintenance of swimming pool water. The ideal chlorine values are between 0.5 and 1.5 ppm.


There are many types of disinfectant products.  The chlorine products are the most used because they quickly eliminate bacteria, mushrooms and other organisms.  However, there are other products of similar efficiency like the bromine and the active oxygen.


Bromine is more effective in hot and calcareous waters; and it does not damage the skin or hair as much, whereas active oxygen needs a dispenser for its use, but it does not irritate the eyes and does not release unpleasant odours.


Therefore, it is essential to frequently analyse the parameters of the water in our pool, in order to keep up with the varying pH and chlorine levels. The use of one product or another will depend on the hardness and quality of the pool water.


An important factor that we must take into account for the maintenance of the pool water is the temperature. The climate and the different weather conditions cause the water temperature to vary, affecting the maintenance and therefore the adequate levels of pH and chlorine.


Ideally, the temperature of the pool water should oscillate between 28º and 30º C (82 to 86ºF). To know the temperature of the pool water, it is enough to use floating thermometers. A correct temperature not only achieves a greater well-being during our baths in the pool, but also ensures a better water quality.

Don’t forget that you’ll find many more swimming pool advices in our social networks. Follow up not to miss anything.


  1. Francisco Montoro says:

    El agua de mi piscina (agua potable de la ciudad de Córdoba), con cloración salina, incluso en época que no tiene uso, tiene tendencia a bajar el pH. Está situada en suelo urbano con poco tráfico y poca densidad de población y no encuentro la causa.
    Podrian decirme las posibles causas de esa tendencia?..

  2. Buenos días,

    El pH de la piscina cambia (sube o baja) en función de diferentes parámetros como la humedad exterior, la temperatura exterior y del agua, por el uso de la piscina… Es totalmente normal que se desequilibre el agua de la piscina. Para ello, necesita echar en la piscina un incrementador de pH si el pH esta bajo o un minorador de pH si el pH esta alto.


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