Chemical Water Balance – Continued

Chemical water balance

Chemical water Balance

Previously discussed adding acid to lower pH and consequently the TA, this has also altered the chemical composition of the water. In doing this you have forced the Calcium Chloride (Calcium Hardness) to begin a chemical binding process that will search for it’s chemical partner (Bicarb) in order to try and stabilise itself. However since you have lowered the amount of Bicarb in the water when you decrease your pH you have taken away the level of partnership required to make a bond between these two chemicals. As a result the Calcium Chloride component will attach itself to any other chemical compound that will provide a balancing effect. Now you know why you see tiles falling of older pools, why surrounding metal develops rust, paint peels off and other distasteful results.

Because water supply varies around the world, we are all dealing with different water. So supply water needs to be checked for TA, Calcium Hardness and pH. Country, city and bore water all differ, so this will need to be taken into account when you need to fill or top up your pool. With a new pool, the pool builder should do this for the start up chemicals required for correct balance.

In the previous article

I mention that the chemicals give strength to the water. This is because we are the ones that interfere with the waters natural capability to balance it’s self. By adding the extra chemicals to it, we aim to manipulate our pool water to change its qualities to levels that are both good for us and our equipment.

In general, the most favorable levels for our body are to have the following water characteristics:

pH level of 7.5 to 7.8

Alkalinity (TA) 80 ppm – 120ppm

Calcium Hardness 200 – 350 ppm

These characteristics are also very favourable to our equipment and provide a chemistry balancing point with a saturation index of (0) or “Neutral” water. In overall perspective a proper balance refers to the means at which the chemicals dissolve and bond together within the water in such a way that the water is neither corrosive nor scaling. So the words corrosive, scaling and neutral are terms that are used to describe the state of the water.

Here I wish to make the point

That the water will attack the pool occupants, the pool equipment and its surroundings all the time even when it is “Neutral”. The aim of properly balanced water is to minimise this impact and make the best use out of your disinfection chemicals.

Some basic tips;

  • Never try to fight Mother Nature
  • Check the make up water supply for TA, CH and pH
  • Always add less chemicals than you need, you can always add more
  • Be patient, as everything needs time to work, this includes water
  • Always add chemical(s) to water, not the other way around.


What is pH anyway?

pH is an artificial measurement which determines to be acidic, 0 to 7 points, neutral 7 points or base 7 – 14 points

0                                                                    7                                                                    14

Very Acidic                                              Neutral                                                         Very Basic

From the water balance chemistry point of view, the pH scale representing the concentration of H+ (Hydrogen) ions in a solution. The more H+ in the water, the better the oxidation and the less HO- (Hydroxide ions). Pure water has the same number of both ions. Acidic solutions have more H+ ions than HO- ions and vice versa for base water. Pool water is made slightly negative (more HO-) because our body pH is higher than 7 points.

In simple terms,

This reflects the fact of whether you end up with corroded equipment. (where pH is 7.2 or lower) or clogs up your piping (where your pH is higher than 7.9 points or more). It also reflects whether you will spend more money on your maintenance or chlorine or both. Further more it may indicate whether you end up with eye, skin, ear or nose complaints. Oily or dry skin types react differently to chlorine as well. If you add chlorine to diesel you get an explosion. So oily skin may experience burning. Watch out for your pH.

Steve Johnson is the Managing Director of “WET” Water Engineered Technologies (Thailand) and offers a broad range of “Commercial & Domestic” water filtration solutions, potable water, Oil Separation & Product Recovery Technologies plus swimming pool design, construction, equipment and consultation.

Steve can be contacted on Tel: +66 ( 0) 848 428 317 or email us here