Treatment of a pool with chlorine : principle and process

Chlorine is well known to owners since it is the product most frequently used to treat swimming pool water. Let’s find out what its exact role is, its main advantages, in what forms it is marketed, how to use it and what is the ideal chlorine level in a swimming pool.

Chlorine, a popular pool disinfectant

The use of this Chemical product is almost unavoidable in order to benefit from flawless bathing water. It eliminates:

  • The mushrooms,
  • Bacteria,
  • The seaweeds.

So chlorine is very useful so that young and old can enjoy a safe water and clear. If it is the most commonly used pool treatment, it is because it has the following advantages:

  • Efficient because of its high algaecidal (against algae) and antibacterial (against bacteria) power,
  • Easy to findit is marketed by swimming pool specialists, specialized brands and supermarkets,
  • Affordable priceit is indeed much cheaper than bromine,
  • Simple d’utilisation,
  • Offered in different formsnamely in powder, in pebbles and in liquid form.

For information, chlorine in powder or in pebbles costs on average €35 for a 5 kg jar, and between €55 and €60 for a 20-litre container (liquid chlorine).

Is chlorine harmful for swimmers?

Some people are reluctant to use chlorine because they suspect it gives their pool water a very unpleasant odor. Yet this chemical is odorless.

On the other hand, this very inconvenient specific odor for which it is criticized is due to the transformation of chlorine into chloramines as soon as it comes into contact with ammonia or organic materials such as cosmetic products, dander, sweat, saliva, but also swimmers’ urine… (yes, some people are insensitive…) .

The pH and temperature of the water also affect the appearance of chloramines in a swimming pool. For example, the chlorine becomes totally ineffective with too high pH.

Chloramines, in addition to giving off a strong smell of chlorine, irritate the eyes and skin of pool users since they are toxic. They can also irritate the throat and nasal passages, even in occasional bathers in a pool treated with chlorine.

No risk irritation or allergy is however not to be feared when the level of chloramines does not exceed 0.3 mg/m3 of water.

Regarding his manipulationit implies some precautions to avoid inhaling, ingesting or getting it in the eyes because it is especially in its solid form that chlorine is irritating to mucous membranes, eyes and skin. It is therefore recommended to wear goggles and a protective mask as well as gloves whenever you have to handle chlorine. And since two precautions are better than one, we do the same if we have to use chlorine in its liquid form.

It makes good sense to store it in a lockable roomvery good ventilated, secet to which children should never have access. It should always be kept in its original packaging, and empty chlorine containers or bottles should be discarded immediately as indicated on the labels. Finally, never transfer chlorine into a container other than the one strictly intended for this chemical product.

How to use chlorine to treat your swimming pool?

The mode of use depends on the form of the chlorine, namely:

  • In poudre (shock chlorine), to be poured directly into the pool water. Its dissolution is very fast. This is the form recommended for shock treatment in a swimming pool that has become impassable where the water is very dirty or very green, or quite simply when restarting after wintering.
  • In pebbles, perfect format to maintain an ideal chlorine level, to be placed in a floating diffuser or in skimmers, once or twice a week depending on the duration of use of the pool and the number of bathers. It is by far the most marketed form because of its ease of use and dosage. Its dissolution is slow.
  • Form liquid (rather reserved for public swimming pools, liquid chlorine is difficult to dose and its handling requires certain precautions.

It should also be noted that there is two types of chlorine.

  • stabilized chlorine UV resistant because it contains a stabilizer. It is odorless, does not modify the pH of the water. It is necessary to be precise as for its dosage because if the chlorine dissolves quickly, it is not the case of the stabilizer which it contains. At too high a dose, the latter ends up accumulating in the pool water, making the chlorine ineffective. Care must therefore be taken to ensure that the level of stabilizer is always less than 60 mg/litre of swimming pool water.
  • Unstabilized chlorine which must be completed with a stabilizer because it loses its effectiveness fairly quickly due to its propensity to degrade under the effect of ultraviolet rays. It is finally little used by the owners of a swimming pool.

Chlorine pool treatment: the right dosage

To measure the chlorine level of the swimming pool, we use chlore-tests. It is strips which also analyze the pH level. The box of 50 units costs about ten euros at most. Some chlorine-tests are marketed in the form of lozengesthem DPD1 being the most effective pellets. The box of 250 costs on average €15.

Finally, there is a more sophisticated way but also more expensive to measure the chlorine level, namely the device electronic tester whose price varies according to the models from 50 to more than 300 €. But it is also the most reliable way which gives a result of high precision since we can thus measure the pH, the total chlorine level but also that of all its components, such as active chlorine, combined chlorine, stabilizer, etc.

Whatever process is used, this does not change the chlorine dosage, which must be respected. For optimal treatment, it is important that the dosage corresponds to the type of chlorine, namely:

  • Stabilized chlorine:

    • From 0.4 and 1.4mg/l: active chlorine,
    • 0.6mg per liter maximum: combined chlorine,
    • Between 7.2 and 7.4 for the pH.

  • Unstabilized chlorine:

    • 2 mg/l at least: active chlorine,
    • 0.6mg per liter maximum: combined chlorine,
    • Between 7.2 and 7.5 for the pH,
    • 25 mg/l: stabilizer (should never exceed 60 mg/l).

Each assay requires vigilance so that everyone can enjoy the swimming in peace. Some people like to make it easy for themselves. They opt for a chlorine regulator. It’s about a metering pump which only works with liquid chlorine. There is no need to intervene manually, the device regulates the rate in real time. A dosing pump costs at least 200 €.

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