Best Pool Shock of 2022

As much as we would like to just dive right into a pool, that’s not the right way to approach backyard swimming. Instead, there’s a specific routine a pool owner needs to perform to maintain clean, safe water. Clearing out floating debris isn’t sufficient. Regular pool chemical cleaning, also known as shocking, is necessary to balance the pH levels and avoid breeding dangerous bacteria. Choosing the right treatment may be tricky unless you’re a chemist or a pool maintenance technician. For this reason, we’ve reviewed five of the best pool shocks on the market in one guide. Additionally, we’ll explain the difference between various shock treatment types and provide detailed instruction on conducting the process.


In the Swim Chlorine Pool Shock

Calcium hypochlorite is the perfect option for pool shocking. It’s generally more powerful than sodium treatments; therefore, less product is necessary to sanitize the water.

In The Swim pool shock contains 68% cal-hypo. It’s strong enough to fight any contaminants while not making the water pH overly acidic. One pound of product is sufficient to treat 10,000 gallons.

This pool shock needs to be pre-dissolved in water. Because this treatment features high chloride content and is more complicated to use than liquid alternatives, it’s best suited for shocking rather than daily sanitation. In The Swim shock can be used for all types of pools, in-ground or above-ground, vinyl, fiberglass, or concrete.


  • Powerful
  • Suitable for any pool
  • Optimal content of available chloride


  • Needs to be pre-dissolved


Nava Chemicals Star Plus Chlorinating Shock Treatment

Nava shock treatment is sodium hypochlorite-based and suitable for vinyl and saltwater pools. Therefore, it won’t cause calcium buildup on your pool equipment.

As the treatment is stabilized, it’s equally effective on sunny days and during the night. An available chlorine level of 55.5% ensures that pH is affected minimally. One pound of shock treats up to 10,000 gallons depending on water contamination level.

Granulated pool shocks don’t have to be pre-dissolved. Instead, pour the granules directly into the water and dispense them on the surface evenly using a brush. Wait a day or two, then test the pool’s chlorine level – if the content of the chemical is below 4ppm, you can safely enter the water.


  • Stabilized
  • No pre-dissolving required
  • Insignificantly affects the pH
  • Suitable for saltwater pools


  • Sodium hypochlorite should be stored according to instructions to avoid hazards


Clorox Pool&Spa Shock Plus

Granulated chloride is one of the most common, traditional types of pool shock. Clorox Pool&Spa Shock Plus contains 58% sodium hypochlorite. It’s acidic enough to easily fight algae and bacteria while not causing significant pH or calcium level increases.

One bottle is enough for 12,000 gallons. The treatment is suitable for saltwater pools and vinyl liners. No pre-dissolving is required.

Clorox is an industry-leading cleaning product brand, and pool treatments are the company’s strong suit. Shock Plus is perfect both for daily pool maintenance and major shocking.

When small amounts of chlorine are used, the water is ready for swimming in 15 minutes. In addition, a native mobile app was developed to provide pool owners with solutions and recommendations on pool care.


  • Suitable for daily sanitation and shocking
  • Optimal level of hypochlorite
  • Doesn’t contain calcium
  • Suitable for saltwater pools


  • Two packs are needed for pools exceeding 12,000 gallons


Ultima Total Control Blended Shock

Sodium hypochlorite is generally used for industrial purposes, for instance, in public pools and hotels. For this reason, it’s rarely available for regular consumers as compared to calcium-based alternatives.

Ultima Total Control is a sodium hypochlorite granulated shock treatment with an algaecide effect. It’s powerful enough to clear the most overgrown water and prevents algae from appearing again.

Most importantly, unlike many competitors, this pool shock works against both green and black algae. Ultima Total Control also improves the overall water clarity and fights dangerous bacteria.

Three pounds of product can treat up to 20,000 gallons. In other words, a pack will be enough for several treatments for an average-sized pool and be enough for one treatment of a large pool. This treatment is compatible with saltwater pools and can be used on any lining surface, including vinyl. It doesn’t require dissolving before use.

The best thing about sodium hypochlorite is that it doesn’t cause calcium levels to increase. However, high levels of calcium may damage pool equipment and make water hard. This often leads to high repair costs or even makes the pool impossible to use.


  • Doesn’t contain calcium
  • Easy to dose
  • Doesn’t require dissolving before use
  • Algaecide effect that fights even black algae


  • Sodium hypochlorite is more hazardous than calcium hypochlorite


HTH Super Green to Blue Shock

HTH Super Green to Blue is a calcium hypochlorite-based pool shock treatment. As indicated by the name, this shock is perfect for removing significant algae buildups. Furthermore, it also prevents algae from growing back after the treatment.

The pack consists of four pouches of 1.15 pounds and is sufficient to sanitize up to 20,000 gallons, depending on the contamination level. The treatment dissolves fast and doesn’t fade vinyl pool liners.

HTH shock is suitable for all types of pools, including saltwater. However, it can’t be used in pools without a waste setting. The heavy-duty flocculant contained in treatment settles dead algae and debris to the bottom of your pool. The waste should then be vacuumed.

HTH Super Green to Blue is straightforward to use. Follow the instructions on the pack to dose the treatment, then pour it directly into the water – no need to dissolve the granules in advance.

If some of the granules settle along the pool’s bottom, use a brush to disperse them. Wait for 6-12 hours and test the water pH level. In just 24 hours, you can enjoy clear pool water.


  • Simple dosing
  • Fights algae and prevents it from growing back
  • Is suitable for vinyl liners
  • Is suitable for saltwater pools


  • May cause calcium level increase if overused

Buyer’s Guide

Finding a suitable chlorine type and correctly shocking is crucial for maintaining your pool’s cleanliness and avoiding hazards. However, chemical terminology on shock packs may be overwhelming even for experienced pool owners. For this reason, we’ve created a brief buyer’s guide to help you get the subject straight.

Calcium Hypochlorite

Calcium hypochlorite is often referred to simply as “cal hypo.” It’s a white, chlorine-smelling powder or granules.

Sometimes, it’s sold in tablets. Calcium hypochlorite is usually poured directly into the water or into the pool skimmer. This type of shock has a highly alkaline pH level, usually about 11-12. The content of free available chlorine ranges from 55% to 75%.

When calcium hypochlorite is added to the pool, chlorine reacts with water forming hydrochloric acid. This acid then eliminates bacteria by combining with them and breaking down cell walls. It’s a powerful and quick way to sanitize a pool. Furthermore, a very small amount of product is needed compared to other pool shock types to reach the required free chlorine level.

This type of shock doesn’t damage pool equipment over time if used correctly. However, proper pre-dissolving is necessary to avoid bleaching.

Calcium hypochlorite doesn’t contain cyanuric acid, a pool stabilizer required for UV protection and correct pH balance. For this reason, chlorine may burn off very quickly if the pool is exposed to the sun. This characteristic may be useful for those wanting a temporary chlorine boost, though it’s generally a drawback. Muriatic acid can be used to stabilize the pH.

Another disadvantage is that calcium hypochlorite contains calcium (pretty apparent) that raises the water hardness level over time. It may also cause water cloudiness, though that’s a solely visual drawback that clears up by itself in a while.

Calcium hypochlorite is one of the cheapest pool shock options on the market. You should be aware of additional expenses, though, such as muriatic acid or calcium remover. It’s also compact, thus easy to transport and store.

While calcium hypochlorite isn’t the best choice for daily chlorination due to the complicated dissolving process, it’s perfect for shocking a pool. By adding about 10 times as much chlorine to the pool as the level of chloramine, you can successfully get rid of algae, bacteria, and other water contaminants.

The best way to test the chloramine level is to use dedicated test strips or liquid reagent test kits. However, if you don’t own any of these, follow your nose – a strong smell of chlorine indicates that a shock is already needed. As calcium hypochlorite is unstable, it’s recommended to use it overnight.

Pool Shock With Algaecide

Both pool shock and algaecide help fight the unappealing greenish color caused by algae growth. However, these two chemical mixes shouldn’t be used at the same time. Chlorine eliminates not only bacteria but also the active ingredients of algaecides, rendering them useless.

Algaecides work best as a prevention method, while chlorine is powerful enough to eliminate large algae buildups. Thus, the best time to use algaecide is after shocking your pool when the chlorine level falls below 5 ppm.

Entirely replacing regular use of algaecide with occasional pool shocking is a bad idea, though. If a large amount of free chlorine combines with algae, less of it is left to fight bacteria, and the shock is much less effective.

You should clean your pool thoroughly before shocking it. If any debris or leaves are left in the water, the chlorine will fight the organic matter rather than algae.

Once the pool is clean, lower the pH level to a minimum, about 7.2. Then, you can start pouring the shock, preferably with at least 70% chlorine content.

While most pool shock manufacturers recommend adding 1 pound of product per 10,000 gallons of water, you may have to increase the dose by two to five times to fight severe algae. The general rule is to repeat shocking until the water turns blueish. Then, give the chlorine 12-48 hours to work and check the chlorine level to make sure it has fallen.

After removing all algae using pool shock, you can use algaecide regularly to prevent it from appearing again. Many pool owners prefer to add algaecide to water once a week or on the sunniest days.

Liquid vs. Granular

Both liquid and granular pool shock treatments contain higher doses of available chlorine than treatments used for daily chlorination. Both kill nearly all living microorganisms and contaminants and help control algae growth. However, there are more differences than similarities between these shock types.

Liquid chlorine is noticeably more affordable than the granular version; the price difference may exceed 60%. Since it’s already liquid, this chlorine form doesn’t need to be dissolved in water and often comes in refillable containers.

Most often, liquid chlorine refers to sodium hypochlorite. It doesn’t have to be scaled and leaves no residue on the pool as it doesn’t contain calcium or cyanuric acid. However, be aware that sodium chlorine may bleach clothes.

The main drawback of sodium hypochlorite is its low availability and strict storage requirements. As it’s a dangerous chemical, it must be kept in a cool, dry, and well-ventilated area. It’s generally used for industrial purposes and therefore is hard to find in regular stores.

Granulated chlorine shock usually comes in one-time-use packets. It’s easier to find and carry than liquid shock and can be stored for longer periods.

Usually, powdered and granulated shock contains calcium hypochlorite, though options with sodium are also available. Calcium hypochlorite is a more powerful sanitizer than sodium, containing 55-75% available chlorine.

Granulated or powdered shock needs to be dissolved before use. This pool shock type successfully fights major algae growth. The main drawback of granulated chlorine, which is usually calcium-based, is the potential increase in water hardness.

The calcium buildup may also affect pool equipment; therefore, this shock type is better suited for occasional shocking than daily treatment.


This section will explain how to perform pool shocking and what to be aware of during the process.

How Much Pool Shock Do I Need for My Pool?

The answer to this question depends on a scope of factors, such as:

  • Pool’s size
  • The last time you shocked your pool
  • Whether any algae have built up
  • Which type of chlorine is used
  • The chlorine content in the shock treatment
  • Pool’s pH level

The general recommendation for powdered or granulated chlorine dosage is 1 pound per every 10,000 gallons of water. However, if you need to get rid of a significant algae buildup, you may have to increase the shock amount by 2-5 times. If your pool appears clean and no algae growth is visible, 6 parts of chlorine per million are sufficient.

When traces of algae are visible on skimmers, the advice is to increase shock dosage to 10ppm. Cloudy or pale green water with a shallow end floor that isn’t clearly visible requires 30-40ppm.

Finally, the maximum recommended amount of shock is 60ppm, used for pools distinctly overgrown with algae. Below, you’ll find a table of the required shock amounts for different pool sizes in case of mildly contaminated water.

Pool size Sodium Hypochlorite Calcium Hypochlorite

Gallons 6 ppm 10 ppm 6 ppm 10 ppm

5000 1 2 300 450

10000 3 5 600 900

15000 4 7 900 1350

20000 6 9 1200 1800

How to Shock Your Pool?

The first step to correctly shocking your pool is making sure it’s really required. Calcium buildup and extremely acidic pH may become more of a problem than algae or bacteria. We’ll discuss the main signs that shocking is needed and the consequences of over-shocking in another section.

The most reliable way is to test the water pH balance and chlorine content using dedicated test strips. After making sure shocking is necessary, you should find the right type of chlorine.

Sodium hypochlorite and calcium hypochlorite work equally well but have varying instructions and dosages. Liquid shock doesn’t need to be dissolved in water, while granulated or powered does.

Chloride in tablets requires a special feeder as it dissolves extremely fast. To find out how much chlorine to use, refer to instructions on the shock pack.

Shocking is best done at dusk, as sunlight burns off unstabilized chlorine. We highly recommend wearing gloves and glasses during the process to protect yourself from chemical evaporation.

Ensure the pool pump is operating and pour the treatment into the water around the edges of the pool. Then, let the pump run for at least six hours. Test the chlorine levels no sooner than 12 hours after shocking to avoid a false reading. Wait for the chlorine level to drop to 1-5ppm before using the pool to prevent skin irritation.

Depending on the pool shock type used, you may have to balance the pH or use a calcium-eliminating treatment afterward.

How Often Should I Shock the Pool?

Shock dosing should be an essential part of any pool owner’s cleaning routine. The general recommendation is to shock the pool when:

  • First filling it up
  • Noticing any traces of algae or slime
  • After periods of frequent use
  • After heavy rainfalls
  • At the start and end of the swimming season

Certain signs indicate your pool requires shocking. Water turning from clear to green is the most apparent one. If pool sanitizing isn’t regular enough or the amount of chlorine used isn’t sufficient, algae start building up. Algae is especially active on sunny days and in high alkaline pH. This may also be a result of an ineffective filtration system.

Another sign your pool needs sanitation is cloudy water. Murky water may be caused by extensive breeding of dangerous bacteria that may be harmful to people or damage the pool’s circulation system.

The best practice is to regularly test the chlorine and bromine levels in pool water. Outdoor pools always require a reading of 1-5ppm chlorine. Higher levels render algaecides ineffective and may cause skin irritation, while lower levels may indicate insufficient sanitation. When the chlorine level falls below 3ppm, your pool requires shocking.

Finally, if you don’t have any testing strips and don’t notice apparent contamination signs, you can determine whether shocking is required by smell. A strong chlorine odor doesn’t indicate the pool is clean. In fact, the opposite – a clean pool should be almost odor-free. The smell is produced by chloramines rather than chlorine.

Will Pool Shock Damage My Pool?

Neither sodium hypochlorite nor calcium hypochlorite will damage your pool if used according to instructions. However, over-shocking the water isn’t that rare of an issue.

At times, it may be caused by the will to get rid of significant algae buildup faster. But most often, this happens when pool owners measure chlorine levels too soon after shocking.

Most test strip manufacturers don’t design their products to withstand extreme levels of chlorine. High chlorine concentration may bleach the test strip, leading to a false reading of nearly zero chlorine level. Consequently, pool owners add even more treatment.

If the required chlorine dose was exceeded insignificantly, leaving the chemical to oxidize under the sunlight may be sufficient to solve the issue.

The worst thing that may happen due to over-shocking your pool is an increase in the calcium level. This can only happen if you’re using calcium hypochlorite or powdered shock, as it contains high amounts of this element.

Calcium hardens the water and leaves a buildup on tiles and pool equipment, such as filtration systems and pipes. This often leads to high repair costs. Furthermore, the problem won’t go away by itself if not treated and may make your pool unusable.

To conclude, use pool shock wisely. No matter how much you hate algae or how cheap was the shock treatment, don’t overuse it. We recommend purchasing professional chemical testing strips to maintain the optimal water chlorine level.

Keep the Water Clean and Stay Safe

Regular shocking is a crucial part of any pool cleaning routine. Hopefully, our guide has helped you understand what to look for in the best pool shock. Remember that while bacteria-contaminated water may be dangerous, so is chlorine. We advise you to always follow safety instructions when working with harsh chemicals.

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