The pH
pH is the key to successful water treatment. Water is characterized by a pH generally between 7.0 and 7.8 (on a scale of 0 to 14, pH expresses acidic or basic character).
- From 0 to 6.9 said that water is acidic
- 7 to 14 said the water is basic.
- In swimming pools, the optimal pH is between 7.2 and 7.4
Water is naturally charged with dissolved elements, calcium and magnesium salts, which affect both the balance and stability of the water’s pH. The pH is corrected by adding acidic or basic products, packaged in powder or liquid form.
- In powder form: pH minus and pH plus powder products are recommended as the powder form is safer to handle.
- In liquid: these pH correctors are designed for automatic dispensers.They are therefore, more powerful, but their use is more restrictive.
In practice, the ‘harder’ the water is (highly charged with dissolved elements), the more difficult it is to permanently change its pH with the help of acidic correctors.
A badly balanced pH can cause various problems:
- Cloudy water,
- Lower effectiveness of disinfectants,
- Eye and skin irritation,
- Development of limestone or algae in the pool,
- Damage to equipment: fasteners, coating, water filtration system, etc.
Total Alkalinity of the Water
The total alkalinity of water, or its TAC (Total Alkalinity Titer), characterizes the buffering capacity of water, i.e. the capacity of an acidic or basic product to influence the pH of water. The higher the TAC, the more difficult it is to vary the pH of the water. Generally speaking, the TAC must be between 8°F and 15°F, i.e. between 80 ppm and 150 ppm. Tip: 1°F = 10 ppm = 10 mg/l of CaCO3 (calcium carbonate).
The TAC value is increased with the addition of the product Acti Alkafix (sodium bicarbonate based) and decreased with the addition of Acti pH Minus powder (sodium bisulphate) or pH Minus liquid (sulphuric acid at 35°).
An unbalanced TAC can lead to :
- Cloudy pool water,
- The appearance of scale deposits,
- Significant and irreversible damage to coverings, whether liner, reinforced membrane, plaster and tile joints,
- Increased use of pH correction products, which will have difficulty stabilizing.
The Hydrotimetric Title of Water (water hardness)
The Hydrotimetric Titer of water (TH) is determined by the concentration of calcium (Ca++) and magnesium (Mg++).
Water is said to be soft if its TH is below 10°F (1°F = 10 mg/l of CaCO3). It is said to be hard, if it is above 35°F. It is important to keep the TH at a value close to 15°F.
The TH value is increased with the addition of a TH + product (based on calcium chloride).
Water that is too hard can cause :
- Limescale deposits in the pool, rough walls, scaling of your filter and heat exchangers,
- Skin and eye irritation for swimmers,
- Cloudy, whitish water...
Conversely, if the water is too soft, it can also promote corrosion of metal parts or walls for concrete pools, as well as eye irritation.
Taylor Table
The Taylor table shows whether the water is balanced and makes it possible to adjust the three parameters (TAC, pH, TH) in order to obtain this balance with a pH value balancing at 7.2.
This table is very easy to use. Simply measure the TAS, the pH and the TH.
- If the 3 points are aligned, then the water is balanced.
- Otherwise, the water will have to be balanced
Steps for balancing water with a pH of 7.2:
- Check the TH value. If it is less than 200 mg/l, increase the TH value to 200 mg/l. Otherwise, keep its value (it is very difficult to decrease the TH value).
- Mark a point on the pH scale at 7.2 and draw a straight line through the TH value and pH = 7.2.
- This straight line cuts through the TAC scale, giving its ideal value to guarantee a balanced water
- Adjust the TAC to the ideal value found (increase or decrease the TAC to obtain this value).
- Adjust pH to 7.2
It is therefore essential to ensure a good water balance (pH, TAC and TH) in order to maintain a healthy water (non-aggressive and not scaling) favouring the optimal action of the disinfectant used.
It is recommended to check the pH and disinfectant level at least once a week.
Finally, it should be noted that the high water temperature favours limescale deposits.
Any questions? Do not hesitate to contact us!
