---
title: "What Is Calcium hardness? Pool Glossary | Marina Pool Services"
description: "Calcium hardness is the amount of dissolved calcium in pool water, and it affects scale and surface wear."
url: https://marinapool.multisites.ai/glossary/calcium-hardness
publisher: Marina Pool Services
phone: +1-817-896-1120
quote: https://marinapool.multisites.ai/contact
---

Water chemistry

# Calcium hardness

Calcium hardness is the amount of dissolved calcium in pool water, and it affects scale and surface wear.

Calcium hardness protects pool surfaces. Water with too little calcium pulls it from plaster and grout, which causes etching and rough spots. Water with too much leaves white or gray [scale](https://marinapool.multisites.ai/glossary/scale) on tile, in the heater, and inside the salt cell.

Heat makes scale worse, and North Texas summers are hot. Test at least monthly. To raise calcium, a pro adds calcium chloride. To lower it, the usual fix is a [partial drain and refill](https://marinapool.multisites.ai/glossary/partial-drain-and-refill) with softer water. Your fill water matters here, so test it too. A [Langelier index](https://marinapool.multisites.ai/glossary/langelier-saturation-index) ties this number to the rest of the balance.

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

## Related terms

-   [Scale](https://marinapool.multisites.ai/glossary/scale)
-   [Langelier Saturation Index](https://marinapool.multisites.ai/glossary/langelier-saturation-index)
-   [Hard water](https://marinapool.multisites.ai/glossary/hard-water)
-   [Partial drain and refill](https://marinapool.multisites.ai/glossary/partial-drain-and-refill)

## 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)

![A pool technician working on an equipment pad](https://marinapool.multisites.ai/_astro/technician-equipment-pad.BW5xZMNY_Zum1K5.webp)