What Is Pool Shock?

Pool shock is a process of adding a large dose of chlorine (or another oxidizer) to your pool water - typically 5 to 10 times the normal amount. This "shock" of chemicals rapidly kills bacteria, algae, and other contaminants that regular chlorine levels can't handle.

Think of it like this: your regular chlorine maintains clean water day-to-day, but shock treatment is like a deep cleaning that eliminates built-up problems all at once.

What Does Shocking a Pool Actually Do?

Shocking your pool serves several critical functions:

1. Kills Bacteria and Pathogens

Swimming pools can harbor harmful bacteria, even when they look clean. Sweat, body oils, urine (yes, it happens), and environmental debris all introduce bacteria. Pool shock delivers a powerful dose of sanitizer that kills these pathogens quickly and thoroughly.

2. Destroys Algae

Tennessee's hot summers create perfect conditions for algae growth. Once algae takes hold, regular chlorine levels can't eliminate it. Shock treatment kills existing algae and prevents new growth. If your pool has turned green, shocking is essential to getting it back to crystal clear.

3. Breaks Down Chloramines

This is the most important reason to shock regularly. When chlorine combines with nitrogen compounds (from sweat, urine, and other contaminants), it creates chloramines - also known as "combined chlorine." Chloramines cause:

• That strong "chlorine smell" people associate with pools (ironically, it means you need MORE chlorine, not less)
• Eye and skin irritation
• Reduced sanitizing effectiveness
• Cloudy water

Shocking breaks apart chloramines and restores your chlorine's effectiveness.

4. Oxidizes Organic Contaminants

Leaves, bugs, pollen, sunscreen, lotions, and other organic materials constantly enter your pool. These contaminants consume your chlorine and cloud your water. Shock treatment oxidizes (breaks down) these materials so your filter can remove them.

5. Restores Water Clarity

A properly shocked pool sparkles. The high chlorine levels eliminate the tiny particles that make water look dull or cloudy, giving you that crystal-clear water everyone wants.

When Should You Shock Your Pool?

In Knoxville's climate, you should shock your pool:

Regular Schedule

• Weekly during summer - June through August, when usage is high and temperatures are hot
• Every 2 weeks in spring/fall - When the pool is used less frequently
• At pool opening - Always shock when you open your pool for the season
• Before pool closing - Shock treatment helps prevent algae during winter months

Special Circumstances

Shock your pool immediately when:

• After heavy pool usage (parties, lots of swimmers)
• After a major rainstorm (rain dilutes chemicals and adds contaminants)
• If water looks cloudy or dull
• If you detect a strong chlorine smell
• If algae appears (you may need to shock multiple times)
• After opening the pool for the season
• If you notice eye or skin irritation

Types of Pool Shock

There are several types of pool shock, each with different uses:

Calcium Hypochlorite (Cal-Hypo)

The most common and affordable option. Contains 65-75% available chlorine. Requires dissolving before adding to the pool. Must wait 8 hours before swimming.

Lithium Hypochlorite

Dissolves quickly and can be added directly to the pool. Doesn't raise calcium levels. More expensive. Wait 4-8 hours before swimming.

Dichlor (Sodium Dichlor)

Stabilized chlorine that dissolves quickly. Good for routine shocking but adds cyanuric acid over time. Wait 15-30 minutes before swimming.

Non-Chlorine Shock (Potassium Monopersulfate)

Oxidizes contaminants without adding chlorine. Good for routine maintenance. Can swim almost immediately after treatment. However, doesn't kill algae or bacteria as effectively as chlorine shock.

How to Shock Your Pool: Step-by-Step

Step 1: Test Your Water

Before shocking, test your pH level. It should be between 7.2 and 7.6. If pH is too high, shock won't work effectively. Adjust pH first if needed.

Step 2: Calculate the Amount Needed

Read the shock product instructions. Typically, you'll need 1-2 pounds of shock per 10,000 gallons of water for routine shocking. For severe algae or cloudy water, you may need 3-4 times that amount.

Step 3: Choose the Right Time

Always shock at dusk or night. Sunlight breaks down chlorine quickly, wasting your shock treatment. Evening shocking gives the chemicals all night to work.

Step 4: Prepare the Shock

Most shock products should be dissolved in a bucket of water first. Never mix different types of shock, and never add water to shock - always add shock to water.

Step 5: Add Shock to the Pool

With your pump running, slowly pour the dissolved shock around the perimeter of the pool. For liquid shock, pour directly into the pool while walking around the edges.

Step 6: Run the Pump

Keep your pump and filter running for at least 8 hours after shocking - overnight is best. This circulates the shock throughout your entire pool and filters out dead algae and contaminants.

Step 7: Test Before Swimming

Before anyone swims, test your chlorine levels. They should be back down to 3 ppm or lower. This typically takes 8-24 hours depending on the shock type and amount used.

Common Shocking Mistakes to Avoid

• Shocking during the day - Sunlight destroys chlorine. You'll waste money and get poor results.
• Not running the pump - Shock must circulate through your entire pool to be effective.
• Using old shock - Shock loses potency over time. Check expiration dates and store in a cool, dry place.
• Not adjusting pH first - High pH makes shock ineffective. Test and adjust pH before shocking.
• Swimming too soon - High chlorine levels can irritate eyes and skin. Wait until levels drop.
• Adding shock through the skimmer - This can damage your equipment. Always add shock directly to the pool.
• Not shocking enough - If your pool has algae or is very cloudy, regular shock doses won't fix it. You may need double or triple doses.

When to Call the Professionals

While shocking is something many pool owners do themselves, there are times when professional service makes sense:

Severe Algae Problems

If your pool has turned completely green or black, you're dealing with a severe algae bloom. This requires professional treatment including multiple shock treatments, specialized algaecides, extensive brushing, and possibly draining. Trying to fix severe algae yourself often just wastes time and money.

Persistent Cloudiness

If shocking doesn't clear up cloudy water, there's an underlying problem - maybe a filtration issue, chemical imbalance, or calcium buildup. Professionals can diagnose and fix the root cause.

Chemical Confusion

Pool chemistry can be complicated. If your levels are consistently off despite your best efforts, a professional pool service can test your water comprehensively and get everything balanced correctly.

Time and Convenience

Many Knoxville pool owners simply don't want to deal with weekly shocking, chemical storage, and maintenance. Professional pool service means you just swim and enjoy - we handle all the chemistry.

The Bottom Line on Pool Shocking

Shocking your pool is essential for maintaining safe, clean, crystal-clear water. It kills bacteria and algae, breaks down contaminants, and keeps your chlorine working effectively. In Knoxville's hot climate, plan on shocking weekly during summer and every two weeks in cooler months.

While shocking is a DIY-friendly task for routine maintenance, severe problems or persistent issues often require professional expertise. If you're struggling with green water, constant cloudiness, or just don't want the hassle of weekly pool chemistry, Prestige Pool and Spa is here to help.

We serve pool owners throughout Knoxville and East Tennessee with honest, affordable pool service. Give us a call - your pool will thank you!