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What is pH?

pH is an indicator of the H+ ions in water that determine acidity or alkalinity.  pH is expressed on a numeric scale ranging from 0 (high acidity) to 14 (high alkalinity or low acidity). The ideal pH value is always between 7.2 and 7.6

Potential problems stemming from a pH imbalance:

If the pH of the water is higher than 7.6:

– Formation of limescale

– Cloudy water

– Disinfectant far less effective

– Eye irritation

If the pH of the water is lower than 7.2:

– Corrosion

– Deterioration of pool shell

– Eye and skin irritation

– Excessive use of disinfectant



How to test and correct pH

To keep the water in your pool in perfect condition, you need to check the pH daily and there several ways to do this:

1. AquaCheck.

This is the simplest method that uses strips of paper that change colour when submerged in water to indicate the pH level.

2. Chlorine-pH test kit.

This is a much more accurate method that consists in filling the compartments of the kit with pool water.  Add a Phenol Red tablet to the water, close the lid tightly and shake until the tablet has dissolved.

When the water changes colour, match the colour of the water with the colour chart on the kit to determine the pH value.

Once you have tested the pH, correct the level if necessary:

1. If the pH is lower than 7.0, add CTX-20 or CTX-25 (sodium hydroxide) to raise the level.

2. If the pH is higher than 7.6, add CTX-10 or CTX-15 (sulphuric acid) to lower the level.

What is alkalinity?

The alkalinity of water is linked to the pH and measures the water’s ability to resist an alteration in the pH level.  The recommended alkalinity is 125–150 ppm.

Measuring and correcting alkalinity

Test strips are a quick way to analyse the most common parameters and they measure by contrast. There are test strips that measure various parameters:

1. 4-in-1 test strips. In addition to total alkalinity, they measure bromine, pH and the hardness of the water.

2. 7- in-1 test strips. They test for water hardness, total and free chlorine, bromine, pH, cyanuric acid and total alkalinity.

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