7
frequently large amounts of pool water. In general its application is found
just before water passes through the filter units. Its sanitizing power is
not pH related.
Mainly because of its strong oxidizing power the return water may contain
only trace concentrations of ozone. It has to be mentioned that ozone is
very unstable and there is anyway the need for low-level chlorination to
ensure sanitizing throughout the whole pool.
THE WATER BALANCE AND LANGELIER INDEX (LI)
The pool water characteristics need to be maintained in a balanced
condition to avoid system failure. Measuring the water balance is
extremely important to predict if the water is corrosive, scaling or balanced.
A saturation index developed by Dr. Wilfred Langelier is widely used to
predict the balance of swimming pool waters. It is an estimation of the
solutions ability to dissolve or precipitate calcium carbonate deposits. A
certain level of this precipitation (filming) is desired to insulate pipes
and boilers from contact with water. When no protective filming is formed,
water is considered to be corrosive. On the other hand scaling does cause
failure because of incrustation problems.
In the treatment and monitoring of pool water, the pool manager must
ensure that related parameters as alkalinity, hardness and pH are duly
taken into consideration.
Calcium Hardness
The presents of calcium in the system is desired to ensure filming on
those places where the temperature is relatively high, like in boilers and
pipes transporting warm water. Scaling must be avoided because it
reduces heat transfer and pump capacity. Beside the calcium carbonate
deposits in the pipes, high scaling values do cause cloudy water.
It is recommended to maintain the calcium hardness value within the
range from 200 to 400 ppm as calcium carbonate (CaCO
3
).
Alkalinity
Alkalinity is the measure of the total concentration of alkaline substances,
mostly bicarbonates, dissolved in the water. The higher the alkalinity the
more resistant the water is to pH change, the alkalinity buffers the water.
At the same time, high alkaline water is a major contributor to scaling
problems like incrustation in filtration equipment, pumps, and piping.
It is recommended to maintain the alkalinity value within the range
from 80 to 125 ppm as calcium carbonate (CaCO
3
).
pH
The pH of the water is an important factor since at lower pH the corrosion
