What is the pH of water ?

The pH or hydrogen potential represents the concentration of hydrogen ions in the water. It allows to define if the water of the pool is basic or acid. The pH is between 0 and 14. The water of a swimming pool must have a neutral pH.

A badly balanced pool pH : the risks

Many factors can cause the pH of your pool water to vary : the outside temperature, the dosage of pool products, the frequency of swimming, etc. An unbalanced pH can cause some inconveniences ;

• Change in the color of the water, which is no longer completely pure,

• Less effective disinfectant products,

• Irritation of the eyes and skin,

• Development of limestone or algae in the pool

• Deterioration of the equipment: fixings, lining, water filtration system, etc.

To prevent these inconveniences, remember to regularly check the pH of your pool.

Check and adjust the pH in your pool

The pH of the water should be checked at least weekly.

There are several techniques, including the use of pool test paper or phenol red.

The tests must be done carefully and accurately. It is advisable to wait the recommended time and not to do anything that would distort the results:

• Perform pH tests in dry place

• Do not shake the test strips

• Do not touch them with your fingers

• Do not leave your products in the sun

• Do not use expired tests: check the expiration date of the products

 If the pH in your pool is not correct, readjust it with a specific product.

To lower or raise the pH of the water;

• pH + products are useful when the water is too acidic, i.e. its pH is below 7

• If, on the contrary, your water is too basic, regulate its pH with a pH (-) product

Read the instructions carefully before using this type of product. Add a small amount and leave it for a few hours to check if the pH has been readjusted before adding more if necessary.

Sometimes the pH can adjust itself, or after a shock treatment. Adjust the pH level only if necessary.

What is water alkalinity ?

TAC, or Total Alkalinity Content, refers to the alkalinity of the water in a pool.

It measures the concentration of minerals, namely bicarbonates and hydroxides in the water, such as sodium and potassium. The more of these minerals, the more alkaline the water is. The lower the concentration, the more acidic the water. After the lack of chlorine, this is the main cause of water problems.

The reason these minerals are so important and must be measured and adjusted is because they neutralize both the acids and bases in the pool water. This is called the "buffering effect" and it is this phenomenon that limits the variations of the pH of the water. Therefore, pH and alkalinity should always be measured and rebalanced simultaneously, because when one of these parameters varies, the other also varies.

How to correct alkalinity ?

When the alkalinity is too high, the skin becomes irritated, the chlorine no longer works, the pH level is disturbed and the water becomes cloudy. To lower the pH, simply use a pH reducer or anti-limescale product. 

When the alkalinity is too low, chlorine odors are detected, the eyes become hot, algae form, the pH is disturbed and the chlorine disappears quickly. To increase the pH, simply add baking soda or a product that increases the pH.

What is water hardness ?

Water hardness depends on the calcium and magnesium content of the water.

Before doing anything else, be sure to test the alkalinity and the water hardness, as these affect the pH test result.

The TH, for Titre Hydrométrique, measures the hardness of the water. If the TH is too low, it can cause eye irritation and can also degrade the liners. On the other hand, if the TH is too high, the limestone in the pool will build up and form solid deposits on all the pool's equipment and pipes. The ideal level of TH is between 8 and 20 degrees (1 degree = 10 ppm or 10 mg / liter).

How to correct water hardness ?

You can use a colorimetric test to measure the T.H. or water hardness. Collect pool water in a test tube and add the reagents. The colors will tell you the T.H.

If you have too much lime in your pool, use an anti-lime product. Manual cleaning of the walls is also essential if lime stains have deposited. Use a pool brush suitable for your coating.

There are products that reduce water hardness or increase water hardness. Ask for more information at the Club Piscine near you.

If in doubt or if you have any questions, always ask a specialist for advice.