Public Pool Regulation

traitement de l'eau des piscines olympiques

Water quality and public pool regulation

The public pool regulation is governed by different standards. Here are some key reminders for good pool water quality management. Water quality in public pools must meet the required standards. Therefore, the following water testing points must be followed:

Regulation and Recommandation:

  • For a swimming pool WITHOUT stabilizer, an active chlorine between 0.4 and 1.4 ppm
  • For a swimming pool WITH stabilizer, a free chlorine of at least 2 ppm
  • Chlorine combined or also called chloramines less than 0.6 ppm
  • The pH between 6.9 and 7.7
  • A minimum of 30 litres of new water per swimmer per day
  • Trichloramine levels in the air below 0.5 mg/m3 (for indoor pools)
  • And the stabilizer level (isocyanuric acid) below 75 ppm

During daily sanitary readings, the following table is used to determine the level of active chlorine in the water.

tableau de correspondance pH et chlore actif

In addition, SYCLOPE also recommends monitoring the TAC and TH to verify the Taylor Balance

  • The TAC (Full Alkalimetric Title) is between 10 and 30°F
  • And the TH (Hydrotimetric Title) is between 10 and 20°F

Water recycling time

The water recycling time must be as follows (ARS standard) :

  • Spa: minimum 2 times the volume per hour
  • Wading pool: 30 minutes
  • Basin with a depth less than or equal to 1.50 m : 1h30
  • Basin with a depth of more than 1.50 m: 4 hours
  • Diving pool or diving pit : 8h

For all basins larger than 200 m², it is mandatory to provide gutters. For those less than 200 m², it is necessary to provide at least one skimmer for every 25 m² of water surface.

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What is the right pH in a public pool?

What is pH?

The pH is defined as the hydrogen potential of the water and measures the acidity of the water from 0 to 14.
In other words, water is considered to be:

  • Acid if the pH is less than 7
  • Neutral if the pH is 7
  • Basic if the pH is higher than 7

pH and Public Swimming Pools

In public and collective swimming pools, regulations indicate that the pH should ideally be close to: 7,2 and 7,4 de pH.
Indeed, it conditions the effectiveness of the disinfectant and the calco-carbonic balance essential for water treatment.

How to measure the water ph?

The ph of the water is measured with a photometer for self-monitoring and a continuous analyzer for online measurement and control.

What is the definition of chorine stabilizer o isocyanuric acid?

Definition

Isocyanuric acid is the stabilizer of chlorine. It is used for outdoor pools to limit the impact of UV rays on the destruction of chlorine. Only isocyanuric acid is not a disinfectant, which is why it is added to the chlorinated product either in the form of pebbles or manually in operation.

The use of stabilizer implies a change of regulation: without stabilizer the regulation is based on active chlorine, with stabilizer it is based on free chlorine with a minimum of 2 ppm to be maintained.

It is recommended that the isocyanuric acid threshold be between 30 and 50 ppm, knowing that above 75 ppm chlorine becomes ineffective.

What is the TAC (full alkalimentary title?

Definition

The TAC is not indicated in the regulations for public pools, but it is recommended to check it at least once a year. Indeed, it corresponds to the quantity of carbonates and bicarbonates in the water. It is expressed in °F or ppm (1°F = 10 ppm) and characterizes the water’s buffering capacity.

  • A water with a low TAC, i.e. less than 10°F, leads to strong variations in pH,
  • Water with a high TAC above 30°F will cause whitish deposits on the water line and difficulties in correcting the pH. In this case, the water is said to be buffered.

How to change the TAC?

To change the TAC:

  • It is necessary to inject baking soda among other things in order to increase it,
  • To reduce it, it is necessary to inject acid.

This is why it is recommended to keep it between 10°F and 30°F to have a sufficient buffering capacity, a guarantee of good water stability.

How to measure the TAC of the water?

To measure the TAC, you have to use a photometer.

photometre pour mesure de la qualité de l'eau

What is the TH (hydrotimetric title)?

TH definition

Like the TAC, it is recommended to follow the TH at least once a year.

The latter corresponds to the amount of calcium and magnesium (limestone) in the water. It is expressed in °F or ppm (1°F = 10 ppm) and characterizes the hardness of the water.

There are no regulations for public pools, but it is recommended to maintain the TH between 10°F and 20°F to avoid corrosion or scaling problems:

  • Water with a low TH below 10°F is very soft water with a tendency to corrode metals
  • A water with a high TH is higher than 20°F is hard water causing the formation of scale on the walls

How to measure the TH of water?

To measure the TH, you have to use a photometer.

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