The Langelier Saturation index or LSI measures the potential for water to be either scale-forming or corrosive. Essentially, it indicates whether the water will deposit calcium carbonate (leading to scaling) or dissolve it (leading to corrosion).
The LSI is calculated using the following parameters: pH, total alkalinity, calcium hardness, total dissolved solids, & temperature.
Interpreting the LSI
- LSI < -0.3: The water is under-saturated with calcium carbonate and is considered corrosive. This can lead to the water dissolving calcium from the pool surfaces and equipment, causing damage.
- LSI between -0.3 and +0.3: The water is considered balanced. It is neither too corrosive nor too scale-forming, which is ideal for pool maintenance.
- LSI > +0.3: The water is over-saturated with calcium carbonate and is considered scale-forming. This can lead to calcium deposits forming on pool surfaces and equipment, which can be difficult to remove.
Maintaining a balanced LSI is crucial for several reasons:
Preventing Damage: Corrosive water can cause significant damage to pool surfaces, plumbing, and equipment. By keeping the LSI within the balanced range, pool owners can prevent costly repairs and extend the life of their pool components.
Ensuring Comfort: Water that is too hard or too soft can be uncomfortable for swimmers. Properly balanced water is gentler on the skin and eyes.
Efficiency of Chemicals: The effectiveness of pool chemicals, such as chlorine, can be impacted by water chemistry. Balanced water ensures that these chemicals work as intended, providing safe and sanitary swimming conditions.
Aesthetic Appeal: Scaling can make pool surfaces look unsightly and can be difficult to clean. Maintaining the correct LSI helps keep the pool looking clean and inviting.