---
title: "What Is Calcium hypochlorite? Pool Glossary | Marina Pool Services"
description: "Calcium hypochlorite, or cal-hypo, is a granular chlorine that adds calcium to the water. Plain-English pool glossary from Marina Pool Services in Grapevine, TX."
url: https://marinapool.multisites.ai/glossary/calcium-hypochlorite
publisher: Marina Pool Services
phone: +1-817-896-1120
quote: https://marinapool.multisites.ai/contact
---

Water chemistry

# Calcium hypochlorite

Calcium hypochlorite, or cal-hypo, is a granular chlorine that adds calcium to the water.

Cal-hypo is a strong, fast shock. It does not add stabilizer, which is a plus. It does add [calcium](https://marinapool.multisites.ai/glossary/calcium-hardness), which can build up over time and cause [scale](https://marinapool.multisites.ai/glossary/scale), especially in hot North Texas summers.

It is also a strong oxidizer. Keep it dry, stored away from acids, other chlorines, and anything that can burn. Never mix it with other products. Pre-dissolve it in a bucket of pool water only if the label says to, and add it at dusk with the pump on. If your hardness is already high, pick [liquid chlorine](https://marinapool.multisites.ai/glossary/liquid-chlorine) instead.

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

## Related terms

-   [Shock](https://marinapool.multisites.ai/glossary/shock)
-   [Calcium hardness](https://marinapool.multisites.ai/glossary/calcium-hardness)
-   [Scale](https://marinapool.multisites.ai/glossary/scale)
-   [Liquid chlorine](https://marinapool.multisites.ai/glossary/liquid-chlorine)

## 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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