pH regulation

for salt water pools

The acidity (pH) of pool water is a parameter that impacts the effectiveness of water treatment and user comfort.

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pH regulation of pool water

A good water balance is an essential parameter for comfortable bathing.
After all, who doesn’t like swimming in soft water that is clear and clean?

With perfectly controlled pH, swimmer comfort is ensured, as is the effectiveness of the water treatment, particularly chlorine-based.
This is because the pH value clearly influences the effectiveness of the treatment.

Unfortunately, the pH level changes constantly with rain, sun, water quality, pool use by swimmers and the products used.
It therefore needs to be regulated to ensure clean water, but also to protect the pool equipment.

Here is everything you need to know about pH regulation of pool water, its operation and its importance in pool maintenance.

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What is pH?

The Hydrogen potential (referred to as pH) is a measurement of the chemical activity of hydrogen ions.

This measurement determines the acidity or alkalinity value of pool water.

The pH measurement scale is between 0 and 14.

  • From pH 0 to pH 6.99, water is acidic.
    Acidic water is aggressive to skin, eyes, and also pool equipment.
    It can damage the coating or liner and causes corrosion of metals, even on a ladder, the structure of a slatted cover, etc.
  • At pH 7, water is NEUTRAL and therefore pleasant on the skin.
  • From pH 7.01 to pH 14: water is ALKALINE (or hard in common terms).
    Hard water is milky, full of calcium.
    It produces a limescale deposit which clogs the filter, the electrode and the pool walls.
    A high pH also impairs the electrolysis treatment, which means that the water will be less effectively disinfected if the pH is not rapidly balanced.


Regulating pH, a legal obligation since 2016

Since April 2016, the new French standard specifies the applicable levels for private pools: NF EN 16713-3.
Its aim?
Improve the balance of pool water to protect swimmers and the environment from nuisances (illnesses, acidity, limescale, etc.) due to poorly or excessively disinfected water.

This standard specifies a tolerance range for pool water pH: from 6.8 to a maximum of 7.6.
This tolerance is wide, but already offers an initial idea of the pH required for children to bathe safely.


What is the ideal pH for a pool?

Stérilor recommends slightly alkaline water with a a pH close to 7.2, like that of human tears.
This way, swimmers won’t have red eyes after swimming a few lengths and the pool equipment will be preserved.

Stérilor pH regulation appliances are adjusted on exit from the factory to continuously ensure this perfect pH level.


Why does the pH of water change over time?

We forget sometimes, but the pool is an aquatic environment like others.
Sunlight, falling leaves, rain, contact with swimmers’ skin, temperature, chemicals used to combat bacteria, etc. will slowly but surely alter its pH over time and during poor weather.
One way of limiting the variation of the pH is to test and maintain the alkaline content (TAC) at around 100 ppm.
Similarly, the hardness (TH) of the water should lie at between 150 and 250 ppm.

Using salt electrolysis treatment tends to raise the pH, while rainwater will tend to lower it.
In all cases, the acidity or alkalinity of the water should be regulated to maintain your pool and prevent equipment from becoming clogged with limescale or suffering corrosion.


How to adjust the pH of pool water?

The simplest way to have a perfectly stable pH in all circumstance is to use a pH regulator.

The role of the pH regulator is extremely simple.
The appliance continuously measures and adjusts the pH of the water.
On your behalf, it preserves the quality of your pool water using a sensor installed in a pipe in the equipment room.
If the level of your pool water exceeds the 7.2 level configured by Stérilor (or by yourself), a pump is activated to inject pH corrector to re-balance the water.

All Stérilor pH regulators are equipped with a proportional injection system to avoid exceeding the specified set point.
The closer the sensor reading is to the set point, the less pH corrector product is injected.
Stérilor technology applies a very simple logic: at optimal treatment efficiency, the less product there is in the water the better it is for swimmers and the planet!

Of course, if the pH is already balanced, the pH regulator simply ensures that it remains so as long as possible without your involvement!

Unless you install an automated regulator, you will need to sample, test and correct the pH of the pool water at least once a week, which can rapidly become time-consuming.

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