SIMPLY
EFFICIENT
How ScaleWatcher Works
ScaleWatcher
Before discussing how ScaleWatcher treats water, it is good to discuss how scale is formed.
Forms
The capacity for water to hold calcium carbonate in a dissolved state varies tremendously as water travels from its natural sources into and through our homes. There are a number of factors that determine how much calcium carbonate may be contained in given volume of water. The most important of these factors are temperature, pH (acidity), and pressure. As long as water has the capacity to hold calcium carbonate in solution, scaling is not a problem. Scaling occurs when water loses it capacity for calcium carbonate, at which time the calcium crystallizes and attaches as scale to surrounding objects.
Let's look at several conditions that change the solubility of calcium carbonate in water.
Temperature is an important factor. Unlike sugar and
salt, the solubility of calcium carbonate decreases with increasing
temperature. This means that when water is heated, it has less capacity
for calcium carbonate. The effect of this is seen as scaling in tea pots
and water heaters. More hardness compounds than calcium have inverse
solubility. Others are calcium sulfate, magnesium hydroxide, and silicon
dioxide.
pH or Acidity changes will change the solubility. The lower the pH, the higher the acidity, the greater the solubility of calcium carbonate. Acid rain caused by air pollution flows into the ground water. This results in the ground water dissolving higher concentrations of calcium carbonate and other hardness compounds. The leading contributor to acid rain is carbon dioxide. CO2 gas dissolves into water forming carbonic acid. This increases the solubility of calcium carbonate. However carbonic acid is unstable. CO2 evaporates out of water, as is seen in soda pop when it loses it fizz. When the CO2 leaves the water, the presence of carbonic acid decreases with a resulting increase in pH, and decrease in acidity. The solubility of calcium carbonate decreases. As the CO2 leaves, so does the dissolved calcium, and it precipitates out as scale.
Pressure changes will also affect the solubility of calcium carbonate. When the pressure of water drops, scale can form. The reason is related to the effect of acidity. Water under pressure can dissolve more CO2. Soda pop keeps its fizz when it is under pressure. Take the cap off, releasing the pressure, and it goes flat. The acidity decreases. The same happens when pressure is released from water with dissolved CO2. Increases in water temperature also force out CO2 with the same effect as releasing pressure.
The important concept to understand is that conditions which are regularly encountered in a home water system, such as water heating, release of pressure, et cetera, change the solubility of calcium carbonate and other hardness compounds. This means they are going to precipitate out of hard water. If this process is left to its normal course, the hardness products will precipitate out as scale.
Unsaturated Water Dissolves Scale
With the calcium ions converted to crystals, the water has capacity to dissolve more calcium. The result is that over a period of time the lime scale in pipes and the water heater dissolve away. In a period of six weeks, a noticeable reduction of scale is seen in pipes and water heaters. In many cases the dissolving of the calcium scale causes some of the scale to flake away and clog nozzle screens. Nozzle clogging is a temporary condition which stops when the descaling has completed.
