Water Chemistry

Water Chemistry and Balanced Water

Correctly balanced water is essential for proper pool maintenance as water has the ability to corrode, dissolve and calcify a wide variety of substances.

Water is a molecule consisting of two hydrogen atoms bound to one oxygen atom : H20.

In nature, occasionally one hydrogen atom can break away from the rest of the molecule forming a positively charged hydrogen ion H+, and a negatively charged hydroxide ion OH-.

It is the proportion of these charged ions to the rest of the water molecules that determines whether the water is acidic H+ or alkaline OH-.

The pH Scale

The level of acidity or alkalinity is measured on the PH scale, which runs from 1.0 (acidic) to 14.0 (alkaline), with 7.0 representing neutral water.

As you will see, pH is critical, as the cause of most swimming pool water problems is incorrect pH levels.

Look at these potential problems caused by incorrect pH :

Low pH (below 7.0)

Ideal pH (7.2-7.6)

High pH (above 7.6)

Eye and skin irritation, and swimming discomfort

Ideal swimming environment

Eye irritation

Excessive sanitizer use

Most effective chlorine sanitation effect

Poor sanitizer efficiency

Water can eat away at plaster, tile grout, cement, metal pipes and equipment

Water is close to neutral - neither wanting calcium nor wanting to give up excess calcium. The ideal pH to achieve balanced water.

Scale can form on pool walls, inside pumps, filters and other equipment causing numerous problems, such as restricted water flow, poor filtration

Etching of plaster


Cloudy Water



Water is a natural breeding ground for bacteria, algae and other contaminants. In addition, swimmers introduce undesirable pollutants into the water in the form of bacteria, dirt, germs, skin particles, body oils, and other body excretions. Pool water must be sterilized to control these potential health hazards.

Sterilizing chemicals when added to pool water kill bacteria, algae and germs. The most common and universally recognized sterilizer for pools is chlorine.

A sterilizer should also perform an oxidizing action. That is, it chemically burns up the dead organic matter so that it does not accumulate in the pool.

Correctly balanced water will protect your pool and equipment, provide a more pleasant swimming environment and enhance the killing power of pool sterilizing chemicals.

Water Treatment

Incorrect or inadequate water treatment can lead to serious problems and needless expense. A regular maintenance routine is the best way to keep your pool looking good.

To start, you need to know the size of your pool in Litres so that you can add the correct quantity of pool chemicals. You’ll need to decide on a sanitation program that suits you. We can help you select an appropriate program that meets your needs.


Chlorine is the proven method of sanitation and is the only sanitation approved by the Australian Health Authorities. There are various forms of chlorine, each with their own unique characteristics…such as effect on pH, solubility, stability etc…

There are also a variety of alternative sanitizers…many of them are either unproven or have variable results. The one that we can recommend, is ozone water treatment. It is a naturally occurring oxidizer and has few side effects. Once expended, it reverts back to oxygen.

In general, you will need a sanitation program which includes a daily sanitizer to keep bacteria and algae under control…then you will also need to shock treat your pool at least once a week or every 10 days over summer.
This is often referred to as super-chlorination – simply an extra dose of chlorine to burn out pool contaminants to keep your pool looking clear and improve your sanitizer efficiency.


Balanced water is a composite of 3 measures :

Total alkalinity
Calcium Hardness

Total Alkalinity refers to the total amount of all alkali compounds (dissolved salts) in the water. These include bicarbonates, carbonates and hydroxides. The water’s total alkalinity determines it’s resistance to large fluctuations in pH levels.
When total alkalinity is high, pH tends to be high. When total alkalinity is low, pH tends to be low. The desirable range of total alkalinity is in the range 80-150 ppm.

The correct total alkalinity level has a stabilizing effect on pH, reducing its tendency to rise or fall.

Increase total alkalinity with poolgard Alkalinity Increase.
Decrease total alkalinity with poolgard Hydrochloric Acid.

As noted above, pH measures the level of acidity or alkalinity of the water. There are several reasons why correct pH is critical to good pool care :

Maintaining an essentially neutral pH is desirable to avoid corrosion to pool equipment and pool surfaces.

Chlorine, when added to water forms hypochlorous acid or hypochlorite ions, the proportion of each indicated by the pH level. Hypochlorous acid (also known as free chlorine) is the active sanitizer, while hypochlorite ions have little effect as a sanitizer.

The adjustment of pH can be achieved by using either poolgard pH Increase or poolgard pH Decrease.

Water always desires to balance itself chemically whereby it is neither wanting any more chemicals, nor wanting to give up excess chemicals. Chemical balance means maintaining the essential ingredient of calcium carbonate at or above the demand of the water for this ingredient. Water’s “hunger” for calcium carbonate can damage or impede the pool system.

The ideal hardness level is dependent on the pool surface, but the general desired range is between 100-250 ppm.

So, to successfully balance your pool water, you need to bring the variables of pH, total alkalinity and calcium hardness into alignment.

Your pool professional can recommend the most suitable balance parameters for your pool and also recommend the necessary steps required to get your pool into perfect balance.