How much pool shock do I need for my pool?

The amount depends on your pool size, current chlorine level, and water conditions. Use the Pool Shock Calculator on Standard Chemicals to determine the exact dose based on your pool.

Does calcium hypochlorite add cyanuric acid (CYA)?

No. Calcium hypochlorite does not add cyanuric acid, making it ideal for pools with high stabilizer levels where additional CYA would reduce chlorine effectiveness.

Why is my pool still green even when chlorine levels are high?

A pool can remain green due to algae growth, poor circulation, or high cyanuric acid levels reducing chlorine effectiveness. In these cases, a stronger shock treatment is typically required.

When should I use pool shock instead of chlorine tablets?

Pool shock is used for rapid chlorine increases to treat algae, cloudy water, and contamination, while chlorine tablets are used for slow, ongoing sanitation and maintenance.

What Is Calcium Hypochlorite Pool Shock?

Q: What is calcium hypochlorite pool shock?

Calcium hypochlorite (cal hypo) is a fast-acting, unstabilized chlorine used to quickly raise chlorine levels, kill algae, and restore water clarity without adding cyanuric acid (CYA).

March 9, 2026

Calcium hypochlorite, commonly called cal hypo, is one of the most widely used chlorine sanitizers for swimming pools. It is a powerful oxidizing agent that kills bacteria, destroys algae, and removes organic contaminants from pool water.

Calcium hypochlorite typically contains a high level of available chlorine, which makes it one of the strongest pool sanitizers available. Because it is unstabilized chlorine, cal hypo works quickly and is often used as a pool shock treatment.

Why Pool Owners Use Calcium Hypochlorite

Pool owners and pool service professionals choose calcium hypochlorite for several important reasons.

High Chlorine Strength

Cal hypo delivers strong sanitizing power, which allows it to raise chlorine levels quickly and effectively.

Rapid Algae Control

Calcium hypochlorite is extremely effective at eliminating algae blooms and restoring green or cloudy pools.

No Cyanuric Acid

Unlike stabilized chlorine tablets, calcium hypochlorite does not add cyanuric acid to the water. This makes it ideal for pools that already have enough stabilizer.

When to Shock a Pool

Pool shock should be used in several common situations:

- After heavy pool use
- After rainstorms
- When algae appears
- When water becomes cloudy
- As part of weekly maintenance

Many pool owners shock their pool once per week during the swimming season to maintain water clarity.

How Much Pool Shock Do You Need?

The amount of shock required depends on:

- Pool size
- Chlorine strength
- Water condition

To determine the correct amount for your pool, use our Pool Shock Calculator.

How Calcium Hypochlorite Works

Calcium hypochlorite releases active chlorine into the water when dissolved. This active sanitizer kills bacteria, destroys algae, oxidizes contaminants, and helps eliminate chloramines.

This process keeps pool water safe, clear, and properly sanitized.

Is Calcium Hypochlorite Safe for Pools?

Yes. When used according to recommended dosing guidelines, calcium hypochlorite is safe for vinyl liner pools, fiberglass pools, and plaster pools.

However, it should always be added properly and never mixed directly with other chemicals.

Best Calcium Hypochlorite Products

Standard Chemicals offers professional-grade calcium hypochlorite pool shock designed for reliable sanitation and water clarity.

Explore our 68% Calcium Hypochlorite Pool Shock for weekly maintenance, algae treatment, and cloudy water recovery.

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