Slow Chlorine Tablets 20 g – 1 kg
EUR-O-TABS 20 g slow chlorine tablets, supplied in a 1 kg pack, are designed for the regular disinfection of water in smaller private swimming pools. Their slow-dissolving formula helps maintain an appropriate chlorine concentration while preventing algae growth.
The 20 g tablet format is distinct from larger 200 g chlorine tablets intended for different pool volumes. Choosing the correct tablet size and following its specific dosing instructions makes routine water treatment easier to manage.
What are 20 g slow chlorine tablets used for?
Slow chlorine is a routine water disinfection treatment with bactericidal and algicidal action. Unlike shock chlorine, which is intended for specific corrective treatments, slow chlorine provides gradual chlorine release for ongoing pool maintenance.
EUR-O-TABS tablets contain symclosene, also known as trichloroisocyanuric acid. This active substance releases chlorine progressively when in contact with pool water.
According to the product label, the tablets are compatible with all pool filtration systems, including cartridge filters.
How many 20 g chlorine tablets should I use?
What is the recommended dosage for a small swimming pool?
The EUR-O-TABS label specifies 1 tablet of 20 g for a swimming pool holding less than 10 m³ of water, placed in the skimmer or a floating dispenser.
Check and maintain the following water parameters:
| Parameter | Label instruction |
|---|---|
| Water pH | 7.0–7.4 |
| Free chlorine | 1.5–3 mg/L |
| Reference dosage | 1 × 20 g tablet for a pool below 10 m³ |
Do not automatically scale this dosage for larger pools, very small water volumes or hot tubs. Those applications require appropriate, specifically validated instructions.
When to add another tablet depends on your pool's treatment needs. Follow the relevant recommendations in the iopool app and check your water regularly, always within the manufacturer's instructions.
How do I use slow chlorine tablets?
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Check the water pH and adjust it to between 7.0 and 7.4 if necessary.
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Confirm the correct dosage. The label specifies one 20 g tablet for a swimming pool below 10 m³.
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Place the tablet in the skimmer or a floating dispenser. Never allow it to rest directly against the pool liner.
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Adjust the daily filtration time. The label recommends a number of filtration hours equal to half the water temperature in °C. For example, water at 26 °C requires 13 hours of filtration under this instruction.
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Check the free chlorine level and continue treatment based on the measured water condition and relevant app recommendations.
Remove the floating dispenser during swimming. For additional guidance, read where to place chlorine tablets in your pool.
Why choose 20 g tablets instead of 200 g tablets?
The difference is the weight of each individual tablet, not simply the pack size. Each EUR-O-TABS tablet in this product weighs 20 g, whereas larger chlorine tablets weigh 200 g.
The 20 g format has a label dosage intended for smaller swimming pools. If you maintain a larger pool, explore our 200 g slow chlorine tablets in a 1 kg pack.
Always check the specific label when changing tablet sizes. Different formats must not be treated as interchangeable doses.
Product specifications
| Specification | Details |
|---|---|
| Commercial name | EUR-O-TABS |
| Treatment type | Slow-release chlorine |
| Form | Slow-dissolving tablets |
| Individual tablet weight | 20 g |
| Total pack weight | 1 kg |
| Active substance | Symclosene (trichloroisocyanuric acid) |
| Active substance content | 98% according to Belgian registration |
| Belgian registration number | BE-REG-01647 |
| Registration holder | B-Care Chemicals |
| Intended action | Bactericidal and algicidal |
Safety and storage instructions
Danger — Handle this biocidal product with care.
The product may intensify fire, is harmful if swallowed, causes serious eye irritation and may irritate the respiratory tract. It is also very toxic to aquatic life with long-lasting effects.
Keep the tablets in their closed original packaging, away from children, moisture, sunlight and heat. The label indicates a storage temperature of 5–25 °C. Wear suitable protective gloves and eye protection when handling the product.
Never mix these tablets with other chemicals, particularly acids. Do not combine them with bromine-based or PHMB treatments, and do not place different treatment products in the skimmer at the same time. Never pour water onto the concentrated product.
Keep tablets away from direct contact with the pool liner. Dispose of unused chemicals and their packaging in accordance with local requirements. Do not release the product into drains or natural waterways.
Always read the full product label and safety information before use.
Manage your pool treatment with iopool
The iopool app helps you follow your pool's water condition and provides treatment recommendations, including guidance on when another dose may be required for a supported setup.
With EcO Start, the iopool smart water analyser, you can follow pH, oxidation-reduction potential (ORP) and water temperature. ORP is not a direct reading of free chlorine, which should be checked separately using a suitable water test.
As symclosene is a stabilised organic chlorine compound, monitoring cyanuric acid is also relevant. Learn more in our guide to pool stabiliser and cyanuric acid.
App guidance supports regular maintenance but does not replace the manufacturer's safety instructions or labelled dosage.
Frequently asked questions
Can I use these chlorine tablets in a hot tub or spa?
The 20 g format is also marketed for spas by some suppliers. However, the supplied label provides a dosage for swimming pools below 10 m³, not a spa-specific treatment protocol. Confirm the applicable authorisation and appropriate spa dosage before use.
Can I put these tablets directly into the pool?
No. The label instructs users to place the tablets in the skimmer or a floating dispenser. Do not allow direct contact with the pool liner.
How often should I replace a chlorine tablet?
Replacement depends on water conditions, testing results and the recommendations available in the iopool app. Always observe the product label rather than applying a fixed schedule to every pool.
Are these tablets suitable for cartridge filters?
Yes. The product label states that the tablets are compatible with pool filtration systems, including cartridge filters, provided the application instructions are followed.
Is slow chlorine the same as shock chlorine?
No. Slow chlorine is intended for ongoing disinfection, while shock chlorine is used for specific corrective treatments. They have different purposes and dosing instructions.