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.


Once you have tested the alkalinity, correct the level accordingly, as follows:

1. If the alkalinity is less than 125 ppm, use an alkalinity enhancer such as CTX-21 (sodium bicarbonate).

2. If the alkalinity is higher than 150 ppm, it is somewhat more complicated to correct. Add the quantity of CTX-10 pH- necessary to convert the bicarbonate alkalinity into carbon dioxide, which is then eliminated as a gas.

What is calcium hardness?

Calcium hardness measures the total quantity of calcium and magnesium present in the water. The recommended hardness ranges between 175 and 300 ppm.

Measuring and correcting water hardness

As with alkalinity, there are various types of test strips that measure water hardness:

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.




Once tested, you can correct the water hardness as follows:

1. If hardness is low, use a calcium hardness enhancer like CTX-22 (calcium chloride)

2. If hardness is high, use a calcium hardness reducer like CTX-605 (disodium oxalate). If the water takes on a milky appearance after adding CTX-605, you will have to add a flocculant.

Lowering water hardness when it is very high is difficult. If the use of CTX-605 is not sufficient, try the following:

– Counteract high calcium hardness by lowering the pH and alkalinity.

– Use a chelating agent / sequestrant.

– Use a resin-based ionic exchange hardness reducer.

– Use a multi-directional magnetisation system (Faraday effect).

– Replace the water in your pool with new water containing little or no calcium hardness.

Cloudiness and flocculants

Pool water often becomes less clear and cloudier as a result of:

– Presence of algae, bacteria and organic matter.

– Precipitation of calcium salts and magnesium.

– Dust from the air or carried in by swimmers.

– Oxidation of iron and manganese salts.

– Mud from rain, etc.

In most of these cases the particles introduced into the water are so small (colloidal) that they cannot be trapped by the filtering equipment. The use of a flocculant causes an increase in the size of the colloidal particles in suspension, which then settle on the bottom of the pool, at which point they are easily eliminated.

For clear, transparent water, we recommend using a clarifier on a weekly basis along with a disinfectant, which will keep the water in perfect condition longer.

PoolGel. It’s never been so easy to enjoy sparkling clear water

Crystal clear water that is easy to achieve, without the need to handle chemicals or complicated dosing systems.Pool Gel

The single dose gel format makes adding the just right amount easier and more accurate. PoolGel collects the smallest particles and algae spores to facilitate their removal.

– Makes the filter more efficient.

– Helps keep the water in your pool sparkling and crystal clear.

– Boosts the efficiency of disinfectants.

CarePods. A revolution in water care

Multifunction maintenance product that addresses three common problems:

– Cloudiness

– Elimination of phosphates

– Generation of foam

There are many advantages to Care Pods: in addition to the fact that the effects are immediate, the pods wrapped in water-soluble film dissolve in just a few minutes and let you forget about maintenance for a little longer.


Each pack contains 4 CarePods wrapped in a water soluble film.

Forget about containers and complicated dosing systems. With CarePods, it’s never been easier to keep your pool crystal clear and algae-free.

Use 1 CarePod per week for a 50m3 pool. Just drop it in the skimmer basket and forget about it!

Natural Clarifier. Clean and transparent water, naturally.

When used once a week, the chitosan-based natural concentrated clarifier (made from crustacean shells) is an effective treatment for preventing foam and keeping water from becoming cloudy. It eliminates the remains of sunscreen and tanning oils as well as excess metals.CTX Natural Clarifier

– Keeps water clean and sparkling by helping the filter to collect the small particles.

– Eliminates remains of creams and oils as well as foam.

– Compatible with all kinds of disinfectants.

– Eliminates excess metals

– Easy to use

– Facilitates faster and easier cleaning by filters

– Improves salt electrolysis performance

Why do algae form?

Algae are single-cell plant organisms that can multiply and proliferate rapidly in water, particularly at moderate temperatures.  Algae spores are introduced into the pool water by wind and feed on photosynthesis.

Types of algae:

Blue (Cyanophyta)
Yellow or mustard (Chrysophyta) Green (Chlorophyta)
Brown (Phaeophyta) Gold (Crysophyta)
Yellow-green (Xanthophyta)
Red (Rhodophyta)

Algae can appear for a number of reasons:

– Deficient filtering system (contaminated sand or cracks)

– Poor disinfection (except black algae)

– Absence of algaecide pH imbalance

– Thick vegetation nearby

– High temperatures

– Other possible factors

Algae are autotrophic plant microorganisms that are introduced into the pool through the air.  Autotrophs are formed from salt minerals such as phosphates, carbon dioxide and light. They use photosynthesis to produce glucose (organic matter) and release oxygen into the atmosphere.

The enriched nutrients in untreated water can lead to algae-infested water. To prevent this, we recommend using a phosphate remover on a weekly basis. Phosphates serve as nutrients for algae, so if there is no food they are unable to reproduce. Using Phosfree weekly will keep your pool algae-free.

If they do appear, treat them as follows to eliminate them:

1. Make sure the pool is full.

2. Switch the filter off.

3. Adjust the pH to between 7.2 and 7.6.

4. Perform a chlorine shock treatment.

5. Add CTX-530 ANTIALGAS EXTRA concentrated algaecide.

6. The next day, scrub the bottom and sides of the pool.

7. Allow the algae to settle.

8. Run your pool cleaner, ensuring the water flows directly down the drain.

9. Filter

10. Start using a weekly phosphate remover (Phosfree)