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I am sure that, even as a new pool owner, you already understand the importance of chlorine in pool sanitation.
But what about pool shock? Do you know what it is, why you need it, and the different types of pool shock? Moreover, which is the best pool shock for you?
In case, you are unclear about all these questions do not worry. Many new pool owners don’t have a good understanding of pool shock, so you are not alone.
More importantly, in this article, I will explain the three types of pool shock, with the pros and cons of each and a comparison table.
Choosing the best pool shock depends on your pool type, current water chemistry, type of algae infestation, and even how often your pool is used.
By the end of this article, you’ll know exactly how to pick the right pool shock for your pool and keep your water sparkling clean and sanitized.
Key Takeaways
- Pool shock sanitizes and restores water clarity by eliminating bacteria and algae.
- Three types: Cal-Hypo, Dichlor, and Non-Chlorine Shock serve different needs.
- Use Cal-Hypo Shock for algae blooms and heavy contamination.
- Choose Dichlor Shock for stabilized chlorine and routine maintenance.
- Opt for Non-Chlorine Shock for fast results and gentle pool care.
- Factors like pool type, water pH, and bather load affect shock choice.
- Follow safety precautions to ensure effective and safe pool shocking.
Table of Contents
What is Pool Shock? How Does it Work?
Pool shock is a concentrated dose of chlorine (or non-chlorine oxidizers), that is added to a swimming pool to rapidly increase the free chlorine from 2-4 ppm to 10-20 ppm.
This level of superchlorination overwhelms pathogens like algae, bacteria, and other contaminants.
Shocking the pool destroys harmful contaminants, breaks down organic waste, and eliminates unpleasant odors caused by chloramines (byproducts of chlorine reacting with organic matter).
How Pool Shock Works
When you add pool shock, it serves multiple functions:
Pool shock sanitizes the water by killing harmful bacteria and viruses that can accumulate in spite of regular chlorination. The action is rapid (typically overnight!)
The pool shock also oxidizes and breaks down organic matter such as body oils, sunscreen, and leaves. These contaminants contribute to cloudy water and reduce the efficiency of your pool’s sanitizer.
Pool shock has the strength to eliminate all algae growth, whether full-blown or in the initial stage.
Shocking helps keep your pool free from green or slimy water by destroying algae growth and preventing regrowth, which can quickly ruin its aesthetic and safety.
Moreover, shocking reinvigorates your pool’s sanitizer. Over time, normal sanitizers like chlorine can lose their effectiveness due to the accumulation of chloramines (compounds formed when chlorine reacts with organic material).
Pool shock breaks apart these chloramines through a process known as breakpoint chlorination, leaving the water fresh, clean, and balanced.
Shocking your pool weekly during the season is a prudent and recommended pool maintenance guideline. You may also shock your pool after storms and heavy rains, pool parties, or any time the water looks or smells off.
Types of Pool Shock
There are three main types of chemicals used for pool shock:
- Calcium Hypochlorite: A common granular form of chlorine that quickly dissolves and raises free chlorine levels.
- Sodium Dichlor: A stabilized form of chlorine that can be used in both indoor and outdoor pools.
- Potassium Monopersulfate: A non-chlorine shock that oxidizes contaminants without adding chlorine, often used for regular maintenance.
As we dive into the types of pool shock, you’ll learn which one is best suited for your specific needs.
Calcium Hypochlorite (Cal-Hypo) Shock
Calcium Hypochlorite, commonly known as Cal-Hypo Shock, is one of the most widely used types of pool shock. It’s a powerful chlorine-based treatment that works quickly to sanitize and oxidize pool water.
Cal-Hypo is especially effective at killing bacteria and eradicating algae, making it a go-to choice for many pool owners.
Pros and Cons of Cal-Hypo Shock
Pros
- Highly effective: Cal-Hypo is excellent at eliminating algae, bacteria, and other contaminants.
- Fast action: Works quickly to restore water clarity and balance.
- Versatile: Suitable for most pool types, including traditional chlorine pools.
- Affordable: It’s often more budget-friendly than other types of shock.
Cons
- Increases calcium hardness: Over time, it can raise the calcium hardness levels in your pool, which may lead to scaling.
- Requires pre-dissolving: Granules need to be dissolved in water before adding to the pool to avoid bleaching the liner.
- Unstable in sunlight: The chlorine in Cal-Hypo breaks down quickly without proper stabilization.
Best Cal-Hypo Shock Products
When choosing a Cal-Hypo product, look for options that offer high purity and fast-dissolving properties. Here are some top picks:
- HTH Super Shock: Known for its high chlorine content (up to 70%), this product works rapidly to clear cloudy water and eliminate contaminants.
- Dry-Tec Pool Shock: A budget-friendly option that effectively sanitizes and oxidizes.
- In The Swim Pool Shock: A budget-friendly option that effectively sanitizes and oxidizes.
HTH Super Shock Treatment
Dry-Tec Cal Hypo Pool Shock
In The Swim Pool Shock
Cal-Hypo pool shock is ideal for regular maintenance and tackling sudden water quality issues.
Dichlor Shock
Dichlor Shock is a stabilized chlorine-based shock. Dichlor is short for “Dichloro-S-Triazinetrione”. Dichlor is manufactured by the chlorination of Cyanuric Acid (CYA). This is the reason Dichlor is stabilized chlorine.
Dichlor Shock, being stabilized, lasts longer in the pool water, even when exposed to the UV rays from the sun. This unique feature can be helpful in some cases.
Pros and Cons of Dichlor Shock
Pros
- Stabilized chlorine: The built-in cyanuric acid protects the chlorine, ensuring it lasts longer in sunny conditions.
- Fast dissolving: Dichlor shock dissolves quickly in water, leaving no residue.
- Gentle on pool surfaces: Ideal for pools with vinyl liners or delicate finishes.
- Doesn’t increase calcium hardness: Unlike Cal-Hypo shock, it won’t contribute to scaling.
Cons
- Adds cyanuric acid: While stabilizers are beneficial, too much cyanuric acid can reduce chlorine effectiveness over time.
- Not as strong as Cal-Hypo: It may take more product to handle heavy contamination or severe algae problems.
Best Dichlor Shock Products
Here are some highly recommended Dichlor shocks:
- Leslie’s Chlor Brite Pool Shock: Maintains clean, sanitized water and kills bacteria, while providing multi-use shocking and chlorination options.
- Clorox Pool&Spa Shock Xtra Blue: Offers stabilized chlorine with fast-dissolving granules, ideal for maintaining clarity.
- In The Swim Sodium Dichlor Shock: Powerful sanitizing powder that destroys bacteria, breaks down contaminants and kills algae.
Leslie’s Chlor Brite Pool Shock
Clorox Pool&Spa Shock Xtra Blue
In The Swim Dichlor Pool Shock
Dichlor shock is particularly useful for regular maintenance, especially in outdoor pools where sunlight tends to deplete chlorine quickly.
However, you need to closely monitor the pool’s cyanuric acid levels to ensure they stay within the ideal range (30–50 ppm).
Non-Chlorine Shock
Non-chlorine shock, often made from potassium monopersulfate (MPS), is a chlorine-free oxidizer designed to break down organic contaminants in pool water.
Unlike chlorine-based shocks, it doesn’t sanitize or kill bacteria, but it’s an excellent choice for reducing chloramines (the compounds that cause unpleasant odors) and improving water clarity.
Pros and Cons of Non-Chlorine Shock
Pros
- Gentle and safe: Doesn’t add chlorine to the pool, making it ideal for sensitive swimmers and frequent use.
- No waiting time: You can swim almost immediately after application.
- Effective at oxidizing organic matter: Removes oils, sweat, and other waste that cloud water and reduce sanitizer effectiveness.
- Works with all pool types: Suitable for saltwater, vinyl, fiberglass, and traditional pools.
Cons
- Doesn’t sanitize: It doesn’t kill algae or bacteria, so it’s often used alongside chlorine-based treatments.
- Less effective for heavy contamination: Not suitable for severe algae blooms or heavy bacteria contamination.
Best Non-Chlorine Shock Products
If you’re looking for reliable non-chlorine options, consider these products:
- Oxy-Brite Non-Chlorine Shock: Powerful non-chlorine shock with unique blue water-brightening crystals. Rids pool water of contaminants.
- Leslie’s Fresh ‘N Clear Shock: Non-chlorine shock provides all the oxidizing strength that you get with a chlorine shock, only without actually using chlorine.
- In The Swim Chlorine-Free Pool Shock: Eliminates organic contaminants and algae for clean, safe pool water.
Oxy-Brite Non-Chlorine Shock
Leslie’s Fresh ‘N Clear Pool Shock
In The Swim Chlorine-Free Shock
Non-chlorine shock can be used as a supplement to chlorine shock but is not really an alternative.
Comparison Table of the 3 Types of Pool Shock
To help you choose the right pool shock for your needs, here’s a side-by-side comparison of Cal-Hypo Shock, Dichlor Shock, and Non-Chlorine Shock based on key features:
| Feature | Cal-Hypo Shock | Dichlor Shock | Non-Chlorine Shock |
| Main Ingredient | Calcium Hypochlorite | Sodium Dichlor | Potassium Monopersulfate (MPS) |
| Chlorine Content | High | Moderate | None |
| Effectiveness on Algae | Excellent | Good | Not effective |
| Effectiveness on Bacteria | Excellent | Good | Not effective |
| UV Stability | None | High (contains stabilizer) | Not applicable |
| Impact on Calcium Hardness | Increases levels | No impact | No impact |
| Ideal for Cloudy Water | Excellent | Excellent | Good |
| Dissolving Time | Requires pre-dissolving | Dissolves quickly | Dissolves quickly |
| Waiting Time to Swim | 8–24 hours | 8–12 hours | 15 minutes |
| Cost | Budget-friendly | Moderate | High |
| Best For | Killing algae and bacteria in chlorine pools | Routine maintenance in outdoor pools | Frequent maintenance with minimal downtime |
Key Takeaways
- Use Cal-Hypo Shock for heavy contamination, such as algae blooms or green water.
- Choose Dichlor Shock for routine maintenance in outdoor pools where sunlight is a