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5 Best Chlorines of 2025

Last Updated - 28/08/2025

1
Best Choice

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Our rankings are cleverly generated from the algorithmic analysis of thousands of customer reviews about products, brands, merchant’s customer service level, popularity, trends and more. The rankings reflect our opinion and should be a good starting point for shopping.

Blue Horizons

Granular Shock Chlorine Tub of 5 Kg- Blue Horizons

Blue Horizons

£37.50

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Main highlights
- How to Apply Chlorine Shock Granules:
- Granular Shock Chlorine is highly effective at ridding sparkling water of algal infestation. Granular Shock Chlorine can be applied using the skimmer. Also use this product if the pool or hot tub has been neglected, if algae has grown on the pool or hot tub's floors and walls, or if there has been an unusually high bather load.
- Granular Shock Chlorine is a highly concentrated chlorine that is used to shock your swimming pool or hot tub water on a regular basis. This should be done every two weeks or more frequently during hot weather or if the water in your pool or hot tub turns green.
- Equivalent to Shock Xtra and Rapid Shock. Helps to prevent and remove algae. Destroys swimmer waste. It can be used for routine disinfecting. pH 11.5. Part of the BOAST system.
- Blue Horizons Granular Shock Chlorine, a calcium hypochlorite granular shock chlorine, can be used to winterise your outdoor pool or hot tub.
- 6- After shock treatment, wait at least 30 minutes for the chlorine level to decrease below 5mg/l before bathing again. Always test your water after dosage and before bathing.
- 5- After using this product, the pool or hot tub water may become briefly hazy; keep the filtration pump running until it clears.
- 4- Repeat the dose/application as needed to obtain the target level.
- 3- Pre-dissolve this product in a clean plastic container at a maximum of 100g per 2.2 gallons (10 litres) water. Stir well to ensure that the substance is completely dissolved. Add the resulting solution to the pool or hot tub while the pump is turned on, preferably near the water inlets for better dispersion.
- 1- Keep pH levels within the optimal range of 7.2-7.6. If the level does not fall within this range, make adjustments. 2- Keep free chlorine residuals in the 1–3mg/l (ppm) range. Shock or oxidising operations should be performed weekly or fortnightly, with a maximum of 10mg/l (ppm) for a complete shock treatment.
£37.50
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Our rankings are cleverly generated from the algorithmic analysis of thousands of customer reviews about products, brands, merchant’s customer service level, popularity, trends and more. The rankings reflect our opinion and should be a good starting point for shopping.

Blu Line

Blu-Line Chlorine Granules 5kg with free test strips

Blu Line

£32.99

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Main highlights
- Top Grade Chlorine Granules for Swimming pools and spas by Blu-Line
- Blu line pool products
- 5kg Easy open and store container
- 10 free test strips
£32.99
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Our rankings are cleverly generated from the algorithmic analysis of thousands of customer reviews about products, brands, merchant’s customer service level, popularity, trends and more. The rankings reflect our opinion and should be a good starting point for shopping.

JOVS INDUSTRIAL CHEMICAL SUPPLIER

JOVS Chlorine Granules 5kg : Stabilized Chemicals for Hot Tubs, Pools, and Spa's - Swimming Cleverness for Rapid Disinfecting and Cleaning, Spa Water Treatment.

JOVS INDUSTRIAL CHEMICAL SUPPLIER

£25.24

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Main highlights
- pH Balance Optimization: Before application, adjust pH levels to the recommended range of 7.2 - 7.6 to enhance bather comfort, protect plants, and ensure efficient chemical usage.
- Versatile Dosing Options: Customize chlorine levels based on water volume with precise dosage recommendations provided. From 1mg/l (ppm) to 3mg/l (ppm), adjust chlorine levels effortlessly for pools of various sizes.
- Startup Dose Recommendation: For freshly filled or drained pools/spas, administer an initial dose of 50mg/l (ppm) of free chlorine, circulated for a minimum of 1 hour, to establish the desired chlorine residual.
- Stabilized Chemical Formula: Formulated with 56% Sodium Dichloroisocyanurate, our chlorine granules provide effective stabilization for maintaining optimal chlorine levels in your water.
- Note: This product is supplied as either a single 5kg container or 5 x 1kg containers, providing you with the same great value.
- Effectively Disinfection: JOVS Chlorine Granule offer rapid disinfecting and cleaning for hot tubs, pools, and paddling pools, ensuring a hygienic environment for your water activities.
- Easy Application: Apply directly to spas with temperatures above 20 degrees Celsius. For lower temperatures or uncertainty, pre-dissolve the granules in water and add the solution while the pump(s) are running.
£25.24
4
Best Value
27% Off

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Our rankings are cleverly generated from the algorithmic analysis of thousands of customer reviews about products, brands, merchant’s customer service level, popularity, trends and more. The rankings reflect our opinion and should be a good starting point for shopping.

Clearwater
27% Off

Clearwater Chlorine Granules for Hot Tub Spa and Swimming Pool Water Treatment for Rapid Disinfecting and Cleaning, Pail, 5 kg, White

Clearwater

£28.99

£39.99
(27% Off)

More Details
Main highlights
- STABILISE CHLORINE LEVELS: to help ensure your water chlorine level stays between 1-3 mg/litre (ppm) for pools and 3-5 mg/Litre (ppm) for hot tubs
- KILL BACTERIA AND ELIMINATE HARMFUL ORGANISMS: so your spa or pool water stays hygienic and healthy
- FAST DISSOLVING GRANULES: get to work instantly - no more waiting around for hours for tablets to dissolve
- EASY TO FOLLOW INSTRUCTIONS: included with the granules help you select the correct amount to apply for the desired increase in chlorine level
- DISINFECT POOL AND HOT TUB WATER: with these stabilised chlorine granules - free active chlorine (FAC) to maintain a healthy swimming environment
£28.99
£39.99 (27% Off)
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Our rankings are cleverly generated from the algorithmic analysis of thousands of customer reviews about products, brands, merchant’s customer service level, popularity, trends and more. The rankings reflect our opinion and should be a good starting point for shopping.

SUDS-ONLINE

SUDS-ONLINE 5KG Stabalised Chlorine Granules - Swimming Pool Chemicals & Spa

SUDS-ONLINE

£24.49

More Details
Main highlights
- Swimming Pools: Routinely use between 2-3ppm residual chlorine in small or domestic pools and 3-5ppm in public or heavily used pools. For each ppm of chlorine increase required use 40g per 25,000 Litres of water.
- Spas and Hot Tubs: To increase the free chlorine level by 2.5ppm, add 5 grams (a teaspoon). On average you should need approx. 1 teaspoon per person using the spa. Maintain a chlorine level of between 2-4ppm and a pH level of 7.2-7.6 in your spa. Re-adjust the pH balance to between 7.2-7.6 for optimum bathing comfort.
- Our chlorine granules are manufactured with a stabilising agent to help prevent the destabilisation and destruction of the chlorine by sunlight and UV rays. This prolongs their usefulness as a sanitiser over other types of non-stabilised chlorine and makes them ideal for use in swimming pools, spas and hot tubs whether located indoor or outdoor. These chlorine granules should be routinely used to help maintain a safe bathing environment.
£24.49

5 Best Chlorines of 2025

Granular Shock Chlorine Tub of 5 Kg- Blue Horizons

Blu-Line Chlorine Granules 5kg with free test strips

JOVS Chlorine Granules 5kg : Stabilized Chemicals for Hot Tubs, Pools, and Spa's - Swimming Cleverness for Rapid Disinfecting and Cleaning, Spa Water Treatment.

Clearwater Chlorine Granules for Hot Tub Spa and Swimming Pool Water Treatment for Rapid Disinfecting and Cleaning, Pail, 5 kg, White

SUDS-ONLINE 5KG Stabalised Chlorine Granules - Swimming Pool Chemicals & Spa

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