4. DETAILS ABOUT THE ORP CHECK
The amount of chlorine required can vary depending on several conditions :
- Covered pool (by sheeting, cover or panels)
Low chlorine requirement (because there is no UV).
- Sudden rise in the number of people using the pool
Very large amounts of chlorine needed, but on a temporary basis.
- Indoor pool or sheltered pool
Reduced need for chlorine (because of low exposure to external pollution), but which tends to increase
depending on the frequency of use of the swimming pool.
Given this range of possible configurations, chlorine production must be managed according to requirements. The
ORP check enables you to react to each of these situations.
The ORP measurement (in mV), reflecting the oxidation (or reduction) potential of the water, is a major indicator of
According to the WHO, an ORP measurement of 650 mV guarantees disinfected water that is itself capable of
disinfecting. Despite the use of this value as a reference, this can only be on a theoretical level, because ORP
measurements can easily vary depending on the following parameters :
- The pH.
- The type of chlorine (stabilised or non-stabilised).
- The presence of dissolved elements that can affect the water (metals, phosphates, surfactants).
- The cleanliness of the filter.
- The presence of stray currents.
- The presence of flocculant (deposit on the ORP probe).
The ORP measurement : - is not a measurement of free chlorine levels.
The ORP measurement :
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ESSENTIAL PREREQUISITES FOR AN OPTIMAL ORP CHECK :
- Stable pH (with a pH regulator).
- Stabilizer level between 20 and 30 ppm.
- Earthing of the pipe where the ORP probe is installed (with a Pool Terre kit).
- Installation of the ORP probe at least 30 cm before the chlorinator cell.
- Balanced water profile (free chlorine levels at 1 ppm, and pH at 7.2).
- ORP setpoint adjusted according to the ORP measurement displayed (a value between 500 and 700 mV can be
considered as correct).
The use of sulphates is permitted, provided they remain at levels below 360 ppm.
The use of copper sulphates is strictly forbidden.
The use of borehole water is strictly prohibited.
When using a chemical (flocculant, waterline cleaning, sequestrant), check the ORP measurement before and
after use of this product. If the ORP measurement drops sharply, stop the electronics unit for a few days, until the
effects of the product on the ORP measurement disappear.
Influence of chloramines on the ORP measurement : as chloramine levels tend to increase, the ORP measurement
tends to decrease.
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The ORP check in no case eliminates the need to regularly check free chlorine levels.
- varies according to free chlorine levels and all elements in the water.
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