Pool shocking (also called super-chlorination) is the process of adding a large dose of chlorine to your pool to eliminate bacteria, algae, and organic contaminants that regular chlorination can't handle.

What is Pool Shock?

Pool shock is a concentrated chlorine product designed to rapidly raise your pool's chlorine level to 10+ ppm. This high concentration:

• Kills bacteria and algae
• Breaks down chloramines (combined chlorine)
• Oxidizes organic contaminants
• Restores chlorine effectiveness
• Clears cloudy water

When to Shock Your Pool

Regular Shocking Schedule

• Weekly: During swimming season
• After heavy use: Pool parties, many swimmers
• After rain: Dilutes chemicals and adds contaminants
• Monthly: During off-season

Problem-Solving Shock

Shock immediately if you notice:

• Cloudy or hazy water
• Strong chlorine smell (chloramines)
• Algae growth (green, yellow, or black spots)
• Free chlorine reading below 3 ppm
• Combined chlorine above 0.5 ppm

Types of Pool Shock

✅ Calcium Hypochlorite (Cal-Hypo)

Strength: 65-70% available chlorine

Best for: Regular shocking, algae treatment

Pros: Strong, long shelf life, cost-effective

Cons: Raises calcium hardness slightly

Price: $3-5 per pound

💧 Sodium Hypochlorite (Liquid)

Strength: 10-12% available chlorine

Best for: Regular maintenance, saltwater pools

Pros: No residue, easy to use

Cons: More expensive, shorter shelf life

Price: $3-4 per gallon

⚡ Sodium Dichlor

Strength: 56% available chlorine

Best for: Spas, indoor pools

Pros: pH neutral, dissolves quickly

Cons: Expensive, adds cyanuric acid

Price: $6-8 per pound

❌ Potassium Monopersulfate

Strength: Non-chlorine oxidizer

Best for: Spas, weekly oxidation

Pros: Swim immediately, no chlorine

Cons: Doesn't sanitize, more expensive

Price: $8-12 per pound

💡 Pro Recommendation:

For most pools, calcium hypochlorite (cal-hypo) is the best choice. It's effective, affordable, and has a long shelf life. Use liquid chlorine for regular maintenance and cal-hypo for weekly shocking.

How Much Shock to Use

Shock Dosing Chart (Cal-Hypo 70%)

Weekly Maintenance:1 lb per 10,000 gallons

After Heavy Use:1.5 lbs per 10,000 gallons

Cloudy Water:2 lbs per 10,000 gallons

Light Green Algae:2-3 lbs per 10,000 gallons

Dark Green Algae:3-5 lbs per 10,000 gallons

Need to calculate your pool volume? Use our pool volume calculator for accurate measurements.

Step-by-Step Shocking Process

Before You Start

⚠️ Safety First:

• Wear safety goggles and gloves
• Never mix different chemicals
• Add chemicals to water, never water to chemicals
• Keep pets and children away
• Have water ready to rinse skin if needed

Step 1: Test Your Water

Before shocking, test and record:

• Free chlorine level
• pH level (should be 7.2-7.6 for best results)
• Total alkalinity

Step 2: Adjust pH if Needed

Shock works best at lower pH. If your pH is above 7.6, add muriatic acid to bring it down to 7.2-7.4. Wait 30 minutes before proceeding.

Step 3: Calculate Shock Amount

Use the dosing chart above or this simple formula:

Pool Volume ÷ 10,000 × Shock Rate = Pounds Needed

Example: 25,000 gal ÷ 10,000 × 1 lb = 2.5 lbs shock

Step 4: Pre-dissolve the Shock

For granular shock:

1. Fill a 5-gallon bucket with pool water
2. Slowly add shock while stirring with a wooden stick
3. Stir until completely dissolved (2-3 minutes)
4. Let settle for 1 minute

Step 5: Add to Pool

With the pump running:

1. Walk around the pool perimeter
2. Pour shock solution slowly into the water
3. Focus on the deep end for better circulation
4. Never pour into skimmer or return jets

Step 6: Run the Pump

Run your pump for at least 8 hours (preferably 24 hours) to circulate the shock throughout the pool and filter out dead contaminants.

Step 7: Test and Wait

After 8 hours, test your chlorine level:

• 3-7 ppm: Safe to swim
• 8-15 ppm: Wait a few more hours
• 15+ ppm: Wait 24 hours or until under 10 ppm

Best Time to Shock

✅ Best Times

• Dusk/Evening: UV won't break down chlorine
• Cloudy days: Less UV degradation
• After pool use: When no one will swim
• Before storms: Prevent contamination

❌ Avoid These Times

• Midday sun: UV destroys chlorine quickly
• Before swimming: Need 8+ hour wait time
• Windy days: Chemicals can blow around
• When raining: Dilutes the shock

Troubleshooting Common Issues

Problem: Chlorine Level Won't Stay Up

Causes: High chlorine demand, algae, high cyanuric acid

Solution: Shock at 2x normal rate, test cyanuric acid (should be under 50 ppm)

Problem: Water Still Cloudy After Shocking

Causes: Poor filtration, high pH, insufficient shock

Solution: Clean filter, adjust pH to 7.2, shock again if needed

Problem: Strong Chlorine Smell After Shocking

Causes: Combined chlorine (chloramines) still present

Solution: Shock again at higher dose, ensure proper pH

Shocking Mistakes to Avoid

Adding shock directly to skimmer

This can damage your equipment and create dangerous gas

Shocking in direct sunlight

UV rays break down chlorine, making shock less effective

Not pre-dissolving granular shock

Undissolved granules can bleach pool surfaces

Swimming too soon after shocking

High chlorine levels can cause skin and eye irritation

✅ Shocking Success Checklist

You've successfully shocked your pool when:

✓ Water is crystal clear
✓ Free chlorine is 3-7 ppm
✓ No chlorine smell (chloramines eliminated)
✓ pH is balanced (7.4-7.6)
✓ No visible algae or contaminants
✓ Filter pressure is normal

⚡ Quick Shocking Guide