Alkalinity Control is the control of alkalinity (or basicity) levels in a system, especially in water - such as swimming pool water, boilers, cooling systems, or industrial water treatment processes.

A detailed explanation follows:

Definition of Alkalinity

Alkalinity is the ability of water to neutralize acids, which mainly come from bicarbonate (HCO₃-), carbonate (CO₃²-), and hydroxide (OH-) ions. This value is usually expressed in units of mg/L CaCO₃.

Objectives of Alkalinity Control

The main objectives of alkalinity control are:

• Maintain the pH stability of water so that it is not too acidic or alkaline.

• Prevent corrosion of metal pipes or equipment due to low pH.

• Avoiding the formation of scale (scaling) due to too high a pH.

• Maintain the effectiveness of other chemicals in the system (e.g. chlorine in swimming pools).

Control Methods

1. Chemical addition:

   • To increase alkalinity: sodium bicarbonate (NaHCO₃) or soda ash (Na₂CO₃).

   • To lower alkalinity: strong acids such as muriatic acid (HCl) or sulfuric acid (H₂SO₄).

2. Routine monitoring:

   • Alkalinity and pH measurements are taken periodically with a test kit or digital device.

Ideal Range

• Swimming pool: 80-120 mg/L CaCO₃

• Boiler feed water: depending on pressure, usually 100-300 mg/L

• Cooling tower: around 100-150 mg/L