---
title: "What Is Langelier Saturation Index? Pool Glossary"
description: "The Langelier Saturation Index is a number that predicts whether pool water will scale or etch surfaces."
url: https://marinapool.multisites.ai/glossary/langelier-saturation-index
publisher: Marina Pool Services
phone: +1-817-896-1120
quote: https://marinapool.multisites.ai/contact
---

Water chemistry

# Langelier Saturation Index

The Langelier Saturation Index is a number that predicts whether pool water will scale or etch surfaces.

The Langelier Saturation Index, or LSI, combines pH, alkalinity, calcium, temperature, and dissolved solids into one score. A score near zero means balanced water. A negative score means the water is hungry for minerals and can etch plaster. A positive score means it tends to drop [scale](https://marinapool.multisites.ai/glossary/scale).

Heat pushes the score up, so summer pools in North Texas lean toward scale. You do not need to do the math by hand. Most pool apps and service tests report it. If it is off, adjust [pH](https://marinapool.multisites.ai/glossary/ph), [alkalinity](https://marinapool.multisites.ai/glossary/total-alkalinity), or [calcium](https://marinapool.multisites.ai/glossary/calcium-hardness) in that order.

[Marina can helpPool Maintenance Services](https://marinapool.multisites.ai/our-services/pool-maintenance-services)

## Related terms

-   [Water balance](https://marinapool.multisites.ai/glossary/water-balance)
-   [Scale](https://marinapool.multisites.ai/glossary/scale)
-   [Calcium hardness](https://marinapool.multisites.ai/glossary/calcium-hardness)
-   [Total dissolved solids](https://marinapool.multisites.ai/glossary/total-dissolved-solids)

## Need a hand with your pool?

Call or text and tell us what your pool needs. Estimates are free for qualifying services, and same-day estimates are possible when the schedule allows.

[Call (817) 896-1120](tel:+1-817-896-1120)[Get a quote](https://marinapool.multisites.ai/contact)

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