Treatment of a swimming pool by salt electrolysis : principle and process

Everyone wants to be able to swim in swimming pool water of impeccable clarity. This obviously requires that it be treated regularly so that it remains clean. Apart from cleaning with a swimming pool robot, it is imperative to use treatment products including the very frequently used chlorine. But if you do not want to be bothered by its smell or be exposed to a risk of skin irritation due to an inappropriate dosage, for example, it is possible to use another process, thesalt electrolysis. Let’s take stock of its principle, the dosages to be observed, its advantages and disadvantages as well as the precautions to be taken.

Salt electrolysis to treat your swimming pool: principle

To benefit from the treatment of swimming pool water thanks to this process, this involves using a electrolyser. It is neither more nor less than a device with electrodes that transforms electrical energy into chemical energy.

The principle of salt electrolysis is simple: the sodium chloride or magnesium chloride that is deposited in the swimming pool if you opt for this process brings chloride ions which, thanks to electrical energy, turn into chlorine. When this chlorine comes into contact with the organic matter of the water, this leads to another chemical reaction, the transformation of part of this chlorine into chloride ions. It is simply a repeating cycle.

Salt electrolysis of a swimming pool: operation

For the cycle to take place, it must begin with increase pond water salinity by directly adding magnesium chloride or sodium chloride (salt). It is of course necessary to respect the dosages, as we will see in more detail later.

The filtration device must be activated so that the now salty water passes through the electrolyser. This must absolutely have been placed downstream (ie after) the heating system and the filter. When the water passes through the cell of the electrolyser equipped with titanium electrodes, the chloride ions are oxidized by the polarized electrodes (obviously at low voltage).

The cycle of transformations then unfolds, as we explained previously. Chloride ions become Cl2 (dichlore) and chlorine immediately becomes free chlorine. Note that depending on the potential hydrogen bathing environment, this chlorine can be either reserve or active.

By this process, the renewal of chloride ions being partial, very little salt is consumed. Some of the sodium or magnesium chlorine becomes combined chlorine during processing when it binds to organic molecules.

Brief anatomy of a swimming pool chlorinator

There are different models, more or less elaborate. But an electrolyser is at least composed of the following elements:

  • A cell,
  • 3, 5 or 7 electrodes depending on the model,
  • Temperature, pH, flow sensors (or flow detector also called Flow switch),
  • A salinity sensor with alert system and automatic stop device if the salt level is insufficient,
  • A pH dosing pump that measures its rate and regulates it independently.
  • Corrosion of stainless steel elements (pool ladder),
  • The degradation of submerged equipment of the automatic cover type,
  • The discoloration of certain elements ensuring the watertightness of the pool…

It is thanks to an electrical box that the electrodes are supplied with electricity.

Some models of ultra-sophisticated chlorinators are even equipped with a Redox sensor which determines the level of chlorine concentration in real time and regulates its production as needed.

Treating your pool with salt electrolysis: dosage to follow and precautions to take

To treat the water in your swimming pool by salt electrolysis, it must contain between 3 and 7 g of salt per liter. This is much less than in seawater, which has around 35 g of salt per litre! It’s necessary always follow the recommended dosage by the chlorinator supplier or obtain prior information from a swimming pool specialist.

Concerning the precautions to takeit must be remembered that it is very important to maintain the temperature of the water above 16°C so that the electrodes are not damaged. Below this temperature (and therefore necessarily during the winter) it is absolutely necessary to stop the operation of the electrolyser.

The electrode cleaning should not be overlooked, especially if you have not opted for a chlorinator model with self-cleaning electrodes. It is recommended to check them and clean at least twice a year to remove any scale deposits.

Remember that pool water evaporates, unlike salt, so it can be more concentrated in salt when its level drops. On the other hand, a small quantity of salt water can be lost when cleaning the filtration system or following a torrential rain which inevitably leads to its dilution. This is why it is necessary to ensure a moderate intake of salt in the pool water when necessary.

It is also prudent to invest in a high-end chlorinator, equipped with an ORP sensor. It is very useful because it makes it possible to avoid setbacks linked to a excess chlorination. Let’s not forget that this can have serious consequences such as:

When choosing a chlorinator to treat your pool, it is best to seek advice from an experienced professional. It is also strongly recommended to have your chlorinator installed by a specialist because expertise is absolutely necessary. A faulty installation or connection can have serious consequences, both on the quality of the water and on the pool itself and all its equipment.

Swimming pool water treatment by salt electrolysis: advantages and disadvantages

This process presents serious assets, to know :

  • Economical over time compared to other treatment systems,
  • natural solution,
  • Ecological,
  • Effective since the active chlorine obtained by electrolysis destroys all organic debris (particles of plant origin, dander, hair, sweat, urine, etc.) but also algae, bacteria, viruses and other micro-organisms,
  • Compatible with all types of swimming pools,
  • Does not give off any unpleasant odor,
  • In compliance with the dosages, presents no risk:
    • irritation of the skin or mucous membranes,
    • allergy,
    • to damage the hair,
    • discoloration and/or deterioration of swimwear.

However, this swimming pool water treatment technique can be criticized for a few disadvantagessuch as :

  • Some difficulty in setting it up,
  • Requires the purchase of an electrolyser,
  • High installation cost,
  • Requires replacement of the electrodes after a few years of use (approximately every 4 years) as they become ineffective over time,
  • Slightly increases the salinity of the pool water but in reasonable proportions, so that there is nothing comparable with sea water,
  • Tends to lead to an increase in the Hydrogen potential (pH) of the bathing water, which makes it necessary to intervene very regularly to revise the pH upwards or downwards.

Note that to overcome the problem of Hydrogen potential fluctuation due to the treatment of swimming pool water by salt electrolysis, it is quite possible to add to the device a pH regulator. Thus, the control of the water just like the injection of a stabilizer product (more or less) is carried out automatically.

Leave a Comment