Automatic Water Balance

Importance of Water Balance

Water balance is critical from the moment a treatment system is filled — even before adding a sanitizer.
Water is naturally aggressive: it will either absorb essential minerals like calcium if they are lacking, or deposit excess minerals if concentrations are too high. This natural behaviour makes it essential to maintain proper water balance to:

• Prevent corrosion,
• Avoid scaling,
• Protect system components and surfaces.

Stabilising the levels of key metals and minerals ensures consistent water chemistry and extends the life of the equipment and infrastructure.

Automatic Water Balance Control with CHEMTROL® Programmable Controllers

The CHEMTROL® Programmable Controllers introduce automatic water balance management through two key methods:

• Saturation Control:
  By calculating the Langelier Saturation Index (LSI), the controller monitors water conditions to prevent the development of scaling or corrosion.

• Conductivity Monitoring and Control:
  By measuring Conductivity and managing Total Dissolved Solids (TDS) levels, the system automatically initiates water replacement to reduce high TDS concentrations and maintain water quality.

Water Balance Control with CHEMTROL® Programmable Controllers

The CHEMTROL® programmable controller range is designed to maintain precise water balance by accounting for key saturation factors such as pH, alkalinity, hardness, and temperature compensation for both conductivity and pH measurements — a crucial process for achieving accurate and reliable readings.

The built-in Langelier Saturation Index (LSI) module automatically monitors water conditions and provides real-time alerts for potential scaling or corrosion risks.

Key Benefits

The integrated temperature compensation and LSI calculation features ensure:

• Higher accuracy of water quality readings,
• Immediate alerts when water conditions move outside the desired safe range.

Understanding Water Balance

From a chemical standpoint:

• Water balance involves controlling inorganic compounds such as calcium and carbonates that dissolve in water.
• Sanitation addresses organic contaminants such as algae, germs, and bacteria.

Key Factors for Water Balance (in order of importance)

1. pH — Ideal range: 7.4 to 8.0,
2. Water Temperature,
3. Total Alkalinity — Ideal range: 80 to 120 ppm,
4. Calcium Hardness — Ideal range: 100 to 450 ppm,
5. Total Dissolved Solids (TDS) — Should not exceed 2,000 ppm.

Langelier Saturation Index (LSI) Monitoring

The Langelier Saturation Index (LSI) calculates the water’s saturation condition based on:

• pH and Temperature sensor inputs,
• Manual entries for Total Alkalinity and Calcium Hardness.

The current water saturation condition is continuously displayed on the Main Screen as:

• “OK” (balanced),
• “Scaling” (high risk of scale formation), or
• “Corrosive” (risk of material damage),

using standard Langelier Index thresholds.
If a scaling or corrosive condition is detected, the system immediately highlights it with a flashing warning on the Main Screen.

How the Langelier Index Works

The LSI is based on research originally developed for boiler and cooling tower water treatment and determines the degree of Calcium Carbonate (CaCO₃) saturation:

$$\text{LSI}=\text{pH}+\text{TF}+\text{AF}+\text{CF}-12.1$$

Where:

• TF = Temperature Factor,
• AF = Alkalinity Factor,
• CF = Calcium Hardness Factor.

Total Dissolved Solids (TDS) also have a minor effect on the calculation.

Simplified, Accurate Monitoring

Manually calculating the Langelier Saturation Index can be tedious and prone to error, requiring reference to multiple data tables.
The CHEMTROL® Programmable Controllers automate this process, ensuring fast, accurate, and reliable monitoring at all times.

Water Saturation and Its Importance

Water saturation is critical because of the aggressive behaviour of dissolved minerals — particularly Calcium Carbonate — which can cause scaling on surfaces or etching of plaster and metallic equipment.

Although the concept of water saturation is relatively new in water treatment, it is essential for professionals to fully understand it.
In the past, water balance was often left to chance, resulting in some systems lasting for years without issue while others required frequent and costly repairs.

Why Proper Control Matters

Maintaining proper water balance and saturation is crucial to:

• Protect water quality,
• Prevent scale formation,
• Avoid corrosive damage to surfaces and equipment.

How We Monitor Saturation

The Conductivity/TDS sensor continuously monitors the concentration of dissolved solids by measuring the water’s conductivity.
Results can be displayed either as:

• Conductivity units (micro-siemens/cm), or
• Total Dissolved Solids (TDS) in parts per million (PPM),

using an operator-selectable conversion factor.