Best Pool Shock Reviews UK 2021 – Top 7 Comparison

It is important to maintain your pool’s chlorine levels to keep your water sanitary and crystal clear. Pool shocking adjusts your pool’s chlorine levels to best fight off contaminants and control unpleasant odors. It is a good idea to shock your pool after periods of heavy rain, long periods of sunlight exposure, and after extended periods of non-use. Additionally, it is wise to shock your pool after heavy partying or entertaining, as these activities cause heavy levels of contamination from sweat or alcohol.

If your pool begins to emit a chlorine scent, it is time to shock your pool. Do your eyes become irritated or itchy after a swim? If the answer is yes, then this is another sign that it is time to shock your pool. Knowing the best pool shocking product can be frustrating, particularly if you are new to pool maintenance. We have put together a few tips to help you get started.

Best Pool Shocks – Top 7 Picks

1. HTH Super Pool Shock (Editor’s Choice)

This HTH shock treatment restores a crystal clear pool in about 24 hours and suits average-size pools. It has a powdered, quick-dissolving formula and does not require complicated prep work. It is gentle on vinyl pool linings and will not cause fading on concrete or tile work. It gently dissolves spots and stains for easier brushing and works well in afternoon or evening sunlight. For best results, add the powder to a bucket of water and then pour the mixture directly into your pool.





2. Clorox Pool&Spa 33512CLX Pool Shock (Runner Up)

This pool shock is effective against green and mustard pool algae and comes with multiple algae-fighting ingredients. It is an ideal pool shock for commercial spas as it treats water in 15 minutes, enabling a quick turn-around when dealing with a large client load. This pool shock helps maintain your filtration system’s health and improve performance. One pack is enough to treat large residential pools, and it’s is suitable as part of a weekly pool cleaning routine.




3. DryTec Calcium Hypochlorite Chlorine Shock Treatment for Swimming Pools (Honorable Mention)

The DryTec brand is a highly respected, trusted brand where pool and spa maintenance is concerned. This pool shock comes with clear, precise instructions and a colorful mixing guide that is easy to follow. It is essential to test your pool’s pH balance and chlorine levels with a test kit before using this pool shock, as accurate mixing yields quick, astonishing results. Best of all, this DryTec pool shock has a long shelf life -convenient for people who use their pools seasonally.




4. Pool Essentials Shock Treatment (Also Consider)

This shock treatment safely removes contaminants like body oils, sweat, and sunblock and comes in individually wrapped water-tight packaging. It is ideal for use at any time of year and has an anti-clumping agent for easy use and storage. This Pool Essentials pool shock performs just as well as pricy, well-known brands and is highly effective against brown algae, a common pool contaminant.




5.In The Swim Chlorine-Free Oxidizing Pool Shock

This non-chlorine pool shock is a must-have for hot tub owners as it gently removes unwanted particles and matter in your hot tub’s water without the harshness of chlorine. It frees up existing chlorine molecules which keep algae and other unwanted organisms at bay. Additionally, it prevents the production of foam, which can discolor or erode your hot tub’s walls, pipes and filtration system. If your pool or hot tub’s water is low on free chlorine, you’ll need to use chlorine along with this pool shock. 









6. Aqua Clear ACL Products Pool Shock

This Aqua Clear pool shock is safe and effective for all pool types, including standard saltwater pools. It has a slow and steady working action and suits pools of any size or design, including above-ground pools. It comes in a convenient liquid form, making it easier to use than standard powdered shocks. Liquid eliminates the need to check wind conditions and does not need pre-mixing before shocking. It has a non-offensive odor and leaves behind no messy residue or build-up.





7. BioGuard Smart Shock

This pool shock features fast-acting algae-killing crystals and has a special formula that suits heavy-use pools, so it is an ideal addition to any household that entertains regularly. It contains multiple germ-fighting ingredients and makes light work of very heavily soiled pools. This product is also gentle enough as a regular pool shock treatment but is a lifesaver for pools that have not been cleaned or shocked for extended periods. For a great season of pool-side fun, this BioGuard pool shock kit is a perfect choice.


Why Is a Clean Pool Important?

A visible side effect of a poorly maintained pool is the presence of algae. Algae is both unsightly and dangerous, as it can cause unwanted accidents. Algae causes pool walls and flooring to become slippery, resulting in falls, bruising, and other injuries. Slips and falls pose a drowning risk for non-swimmers, even in shallow, small swimming pools.

Lack of maintenance causes pool water to become a breeding ground for harmful bacterial growth, which causes illnesses like ear infections, rashes, respiratory troubles, or itchy eyes. Luckily, regular shocking and maintenance minimize these risks considerably. Of course, an added benefit of regular shocks is a sparkling, inviting swimming pool.

Shocking Your Pool: The Basics

Pool water uses three measurements of chlorine levels: total chlorine, combined chlorine, and free chlorine.

Free chlorine

“Free” chlorine kills algae and other unwanted substances and minimizes particles that cause a cloudy or murky appearance. Free chlorine comprises stable, uninhibited chlorine molecules that are free to interact with the unwanted organisms and substances in your pool’s water. In this context, “interaction” means oxidizing cloudy water, destroying algae, and killing harmful bacteria. Excess levels of free chlorine cause severe skin and eye irritation-make sure you follow all shocking instructions correctly.

Combined chlorine

Combined chlorine refers to chlorine particles combined with other chemical particles like ammonia or nitrogen. These chlorine particles are ineffective at tackling unwanted contaminants and cause a heightened scent of chlorine. In addition, high levels of combined chlorine cause skin and eye discomfort. As a general rule, keep your swimming pool’s combined chlorine levels to 0.2 ppm by regularly testing and shocking your pool’s water.

Total chlorine

As the name implies, total chlorine is the sum of free and combined chlorine. Bear in mind that total chlorine does not reflect the ratio of combined chlorine and free chlorine.

Pool shocking separates combined chlorine particles, which “frees” them to kill algae and other organisms. Pool shock products come in chlorinated and non-chlorinated formulas to best deal with multiple pool sanitation issues. As a general rule, you should always read all instructions to get the most out of your pool shock.


Before shocking your pool, it is necessary to test your pool’s water using a testing kit. These testing kits measure chlorine, microbial and other chemical contents. The results of testing will determine the best type of shock for your pool.

Chlorinated versus non-chlorinated pool shocks

Chlorinated pool shocks generally do not need additional chlorine to maintain sanitary pool water. Non-chlorinated shocks require additional chlorine products if free chlorine levels are too low. Both of these types of pool shocks tackle murkiness and separate combined chlorine molecules.

Your pool’s size

Pool shock products come with specific mixing and usage instructions. Large pools need a large volume of product for best results, while smaller pools will need less product. Using incorrect amounts can cause excess amounts of chlorine or provide insufficient sanitizing power. Before using a pool shock, you should calculate your pool’s volume.

What is the volume of my pool?

Figuring out your pool’s volume is a simple process. First, carefully measure your pool’s length, width, and depth in feet. Write down these measurements, as you will need to do a little mathematics with these numbers. Multiply the length, width, and depth, and then multiply the total by 7.5. The final number will be your pool’s volume in gallons, as one cubic foot contains 7.5 gallons of water.

Pool usage

Swimming pools used less than three times a week will need fewer shock treatments than a regularly-used pool. Regular use exposes your pool’s water to high levels of human by-products. These by-products eventually turn free chlorine into combined chlorine. Pools used daily should be shocked once a week, while pools used a few times a month can benefit from one to two shocks per month.

It’s Time To Shock!

We’ve put together our favorite pool shock products and outlined the ins and outs of pool shocking. As a recap, we’ve discussed types of chlorine, how pool shocks work, and the consequences of an unsanitary swimming pool. Clean, clear pool water minimizes accidents, reduces common pool-related illnesses, and makes for a more enjoyable time. Happy swimming!

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