Pool Water Chemistry

Pool water chemistry is the most misunderstood, yet vital component to overall pool care. Not only does proper water chemistry protect the swimmers using the pool, but it also protects the pool surface and the equipment. Gas heaters, electrical heat-pumps, filters, and even a vinyl-liner can all suffer severe damage from unbalanced pool water. In order to clear up some of the confusion surrounding this subject, we have listed some of the more important water chemistry terms below.

The Chemistry of your pool water is sometimes the most confusing, yet most important part of your pool care.  Any piece of pool equipment that is touched by pool water can be damaged if the water chemistry is not properly balanced. So let’s look at some of the issues regarding pool water chemistry.

Chlorine Sanitizers

Chlorine Sanitizers fulfill two functions. First, they sanitize your pool water, which is killing all the bacteria that can accumulate. Secondly, they oxidize your pool water breaking down ammonia, and other swimmer related byproducts. They also, at proper levels, kill algae spores before they have a chance to propagate. Levels of sanitizers must be kept at optimum levels so they can quickly kill or treat whatever contaminants that can come into your pool waters. The amount of active chlorine in your pool water should be in the range of 1.5 and 3.0 parts per million.

Calcium Hardness

Calcium Hardness speaks to how much Calcium (or other hardeners like magnesium) is in your pool. Calcium hardness that is too high can cause scale, which can make the water cloudy and discolor plaster.  The correct levels for calcium hardness should be between 200 and 300 parts per million.

Total Alkalinity (TA)

TA is the measure of your pool water’s ability to neutralize acids. Your pool water’s ability to neutralize acid determines how easy it is to balance your pool water chemistry.  TA is expressed as parts per million (ppm). The ideal range of TA for your pool is between 80 and 120 ppm. Carefully maintaining the alkalinity level of your pool will facilitate accurate measurements and control of chlorine, pH, and hardness properties of your water and simplify your swimming pool maintenance.

Acidity/Alkalinity (pH)

pH is a measure of how acidic or basic the water is.  pH is a logarithmic scale from 0-14, with 7 being neutral.  Below 7.0 and a substance is defined as being acidic, while levels above 7 are said to be basic or alkaline.  Everything that enters your pool has a pH value. To have pH in balance we adjust the water with additions of pH increasers (bases) or pH de-creasers (acids) to achieve the range of 7.2 – 7.8. 

If your testing (recommended daily) of the water shows a pH value below 7.0 the water is in a corrosive (acidic) condition and you will need to add a base to bring the pH into a more basic range to prevent corrosion. It doesn’t take too long for a low pH condition to weaken vinyl, strip heat exchangers, and pit plaster.  Conversely, if the pH is above 7.8, we are in a scaling (basic) condition and must add an acid to bring down the pH to prevent the formation of scale or calcium deposits on our tile, in the filter, or even precipitation out of solution into a cloudy water condition.

Stabilizer

Stabilizer, usually Cyanuric acid, is used to prolong the potency of Chlorine in the water of a swimming pool. Of the two types of chlorines that are available on the market there are stabilized and non-stabilized. Granular chlorine tends to be more potent than it’s stabilized cousin and more effective at treating algae or cloudy water.  If you use non-stabilized chlorine you should add stabilizer to your pool after balancing the pool water. Cyanuric Acid levels are optimum in the 40 to 80 parts per million range.