What is Redox control for swimming pools ?

What is Redox control?

Redox control, short for REDuction and OXidation, also known as ORP (Oxidation Reduction Potential), is a physico-chemical parameter that measures the oxidizing or reducing power of pool water. Its role is not to measure the quantity of disinfectant product, but its concentration in the pool water.

What is the role of Redox control?

Redox control measures the water's ability to destroy bacteria, germs, pollutants... and easily controls the disinfection power of the water.
It is measured in millivolts on a negative and positive scale. The higher the value, the more oxidizing the water is.

In nature, some substances have negative electrons, others have positive electrons. Some seek electrons, others want to get rid of them. It's the search for balance.

When the Redox control value is positive, the pool water treated with chlorine, bromine, or salt, is loaded with oxidizing agents. When these agents encounter reducing agents, such as algae, bacteria, viruses, sweat... a Redox reaction is created. They take back the electrons and thus destroy them, leaving healthy water.

For which pool is Redox control suitable?

Redox control is essential when:

  • It is not specifically useful when treatment is manual but essential if the pool has automatic chlorine treatment or salt electrolysis.
  • The pool is covered by a cover, a shutter, if the pool is indoors, or if the pool is under cover.
When the pool is covered and the filtration is running, the chlorine produced by the devices cannot be destroyed (chlorine) or converted into salt (salt electrolysis) by UV. The chlorine accumulates and concentrates, it becomes aggressive and deteriorates liners, pipes, and equipment... making swimming unpleasant, the water stings, and an unpleasant chlorine odor emerges...
In these cases, Redox control is essential, it prevents over-chlorination.

How to measure Redox control?

There are no test strips for Redox control. However, a portable electronic tester, often associated with a pH tester and/or an electronic thermometer, can be purchased from pool specialists. Ideally, the Redox box and its measuring probe should be installed in the technical room.
Combined with the pH regulator, Redox analysis is reliable and avoids human intervention.

What is the correct level for perfect pool disinfection?

There is no rule, nor mathematical formula, only tables give an approximation of the Redox value depending on the disinfectant and the pH level of the water.

It is agreed and verified that when the pH is between 7.2 and 7.4; the Redox should be between 740 and 760 mV. A Redox value too low, below 650mV, indicates that the water is not sufficiently disinfectant. Bacteria, algae, and viruses can proliferate in the water. They will be eliminated more slowly or improperly.
To increase the Redox value, simply increase the amount of disinfectant in the pool, add chlorine or bromine, or increase the filtration time for salt electrolysis.
A Redox value too high, above 850 mV, makes chlorine aggressive to the skin, eyes, but also to pool accessories, the liner...

Redox control is a tool that allows automatic control of the concentration of disinfectant in pool water and therefore its quality. It "measures" the level and power of water disinfectant. It regulates for you, the concentration of disinfectant regardless of usage conditions and weather conditions. Once calibrated, water treatment is optimized.

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