FAQ chlorine
Table of contents
What is the difference between fast-acting and slow-release chlorine?Is inorganic chlorine the same as unstabilised chlorine? And is organic chlorine the same as stabilised chlorine?
What is the difference between stabilised (organic) and unstabilised (inorganic) chlorine?
What are the advantages and disadvantages of stabilised and unstabilised chlorine?
In what forms does chlorine exist?
How much chlorine should be in my swimming pool?
Help, the chlorine level in my swimming pool is far too high! What can I do?
What if I am sensitive or allergic to chlorine? Are there alternatives for keeping my swimming pool clean?
What is the difference between fast-acting and slow-release chlorine?
Fast-acting chlorine
Fast-acting chlorine raises the chlorine level in the pool water quickly. It dissolves quickly and starts working almost immediately. That is why it is ideal for:
• when starting up the swimming pool
• for a chlorine shock treatment when the water is dirty or cloudy
• after heavy use by many swimmers
• during hot and sunny periods, when UV rays break down the chlorine more quickly and bacteria and algae are more likely to develop
Slow-release chlorine
Slow-release chlorine dissolves gradually and releases chlorine evenly. This keeps the chlorine level stable and ensures the water remains disinfected for several days.
Conclusion
Fast-acting chlorine is best used to quickly raise the chlorine level or adjust the water parameters. Slow-release chlorine is the ideal choice for daily maintenance and long-term protection of your pool water. Together, they ensure a clear and hygienic pool.
Tip from pool boy Marcel: adjust the pH level first before adding chlorine
A correct pH level ensures that the chlorine can work effectively. The ideal level is between 7.0 and 7.6. Test the pool water using a test strip and adjust the pH if necessary using pH Up or pH Down in liquid or powder form. Only then should you add chlorine to ensure maximum disinfection.
Is inorganic chlorine the same as unstabilised chlorine? And is organic chlorine the same as stabilised chlorine?
Yes, they are synonyms for the same type of chlorine.
What is the difference between stabilised (organic) and unstabilised (inorganic) chlorine?
Stabilised chlorine contains a stabiliser in addition to active chlorine. This is usually cyanic acid.
What are the advantages and disadvantages of stabilised and unstabilised chlorine?
Stabilised (organic) chlorine
The advantages
• Better protection against UV radiation
Stabilised chlorine contains cyanuric acid, a stabiliser that protects the active chlorine from breaking down in sunlight. This makes it the ideal choice for outdoor swimming pools that get a lot of sun.
• Economical to use
As the chlorine breaks down more slowly, you need less of it. That’s user-friendly and cost-effective too!
• More stable water quality
The chlorine level fluctuates less, which helps keep bacteria and algae under better control and keeps the water clear for longer.
The disadvantages
• Accumulation of the stabiliser (cyanic acid)
With every dose, extra stabiliser ends up in the pool water. Over time, the concentration can become too high, making the chlorine less effective at disinfecting. If the concentration of cyanic acid becomes too high, it may be necessary to replace some of the pool water. So keep a close eye on the levels!
• Less suitable for shock treatments
Is the water green, cloudy or heavily contaminated? If so, stabilised chlorine is less suitable for giving the chlorine level a quick boost. For a powerful shock treatment, it is better to opt for unstabilised chlorine.
Unstabilised (inorganic) chlorine
The advantages
• Fast & powerful action
Unstabilised/inorganic chlorine dissolves quickly in the water and takes effect almost immediately. This means that bacteria, algae and other contaminants are tackled swiftly.
• Ideal for shock treatment
Unstabilised chlorine rapidly increases the chlorine level and helps to quickly restore cloudy, green or contaminated pool water to a clear and hygienic state.
• No build-up of stabiliser
As this type of chlorine does not contain cyanuric acid, no stabiliser builds up in the pool water. This means the chlorine continues to work efficiently and you need to change the water less frequently.
The disadvantages
• Faster breakdown due to sunlight
Inorganic chlorine breaks down more quickly when exposed to UV rays. In warm, sunny weather, you will therefore need to add a new dose sooner.
• Add more frequently
This type of chlorine works quickly, but as a result, its effects wear off more quickly too. To maintain the chlorine level, you therefore need to check the water more often and top it up.
Conclusion:
Both stabilised (organic) and unstabilised (inorganic) chlorine ensure effective disinfection of swimming pool water. However, each type has its own specific application.
For the daily maintenance of an outdoor swimming pool, stabilised chlorine is often the best choice, as it is more resistant to degradation by sunlight. Unstabilised chlorine, on the other hand, is ideal for shock treatments and for indoor swimming pools, where UV radiation is not a factor.
What forms does chlorine come in?
Chlorine for swimming pools is available in granules, tablets and sticks. Each form has its own advantages and uses.
• Chlorine granules:
Chlorine granules consist of small granules that dissolve quickly in water. You can add them directly to the pool or dissolve them first in a bucket of water and then distribute them evenly. You therefore do not need a skimmer or chlorine dispenser for this type of chlorine. Because it works quickly, granules are ideal for starting up the pool or for a shock treatment. Thanks to the granule form, you can measure out the quantity accurately. That is why it is the best choice for small to medium-sized swimming pools.
Features:
• Ideal for small to medium-sized swimming pools
• Perfect for starting up the pool and for a chlorine shock treatment when the water is green or cloudy
• Fast-acting with quick results, but also wears off more quickly
• Can be dosed accurately
• No skimmer or chlorine dispenser/chlorine floater required
• Chlorine tablets:
Chlorine tablets are available in various sizes, usually 20 g and 200 g. Small tablets are suitable for children’s pools and above-ground pools, whilst large tablets are ideal for medium to large pools. Place these tablets in a chlorine dispenser or skimmer, which releases the chlorine evenly. Always check that your chlorine dispenser is suitable for large or small tablets.
Features:
• Ideal for small, medium and large swimming pools – depending on the size of the tablets
• Long-lasting and steady release of chlorine
• Requires less maintenance
• Easy to use
• Less precise to dose than granules
• Chlorine sticks:
Granules and tablets are the most popular options, so you may never have heard of chlorine sticks. These sticks are elongated chlorine blocks that dissolve even more slowly than traditional tablets. This makes them ideal for larger swimming pools.
Features:
• Ideal for larger swimming pools
• Very long-lasting
• Low maintenance
• Even release of chlorine
• Less accurate
• Less suitable for rapid adjustments to chlorine levels
Conclusion: which option will you choose?
The best choice depends on the size of your pool and the treatment required. For daily maintenance, tablets or sticks are preferable, whilst granules are often used for starting up the pool or for a shock treatment.
You can also combine the different forms. For example, you can use tablets for regular maintenance and granules when the water needs an extra boost of chlorine.
Tip from pool boy Marcel:
Check the water parameters regularly and always dose according to the recommended guidelines. Too much chlorine is no better than too little. To measure is to know!
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How much chlorine should I put in my swimming pool?
The correct chlorine level is essential for clear, hygienic pool water. Too little chlorine can lead to algae growth, bacteria and cloudy water. Too much chlorine, on the other hand, can cause skin irritation, itchy eyes and an unpleasant swimming experience.
The correct dosage depends on the type of chlorine you are using and the amount of water in your pool. You should therefore always follow the dosage instructions on the packaging. In addition, there are various factors that affect chlorine consumption:
- Hot weather and heatwaves: higher temperatures encourage the growth of bacteria and algae, whilst UV radiation breaks down chlorine more quickly. This is certainly the case with unstabilised/inorganic chlorine.
- Heavy rainfall: rainwater can disrupt the water balance.
- Intensive use: the more swimmers there are, the more chlorine is needed to keep the water clean and safe.
Don’t forget the pH level
What’s more, an incorrect pH level can prevent your chlorine from working properly. Always check the water parameters first before adding any products to the pool, and especially when using chlorine. The ideal chlorine level is between 1 and 2.5 mg/l of water.
Help, the chlorine level in my pool is far too high! What should I do?
Is the chlorine level higher than 3 mg/l? If so, the pool water contains more chlorine than recommended. It is advisable to temporarily stop swimming until the level returns to the ideal range. If you don’t do this, you may experience skin or eye irritation. Your pool itself and its accessories/parts will also wear out more quickly. Furthermore, your swimwear may fade due to the chlorine present.
Step-by-step guide to reducing chlorine levels:
1. Stop adding chlorine temporarily
It may seem obvious, but we’d still like to mention it. Do not add any new chlorine for the time being, and remove any tablets still in the skimmer or chlorine dispenser.
2. Keep your filter pump running
Good water circulation helps to distribute the pool water evenly and keep the water quality stable.
3. Let the sun do its work
Do you usually cover the pool with a tarpaulin? If so, leave the pool uncovered for a while. UV rays naturally break down free chlorine, causing the level to drop gradually.
These simple steps often go a long way. Is the chlorine level still too high? Then it is advisable to replace some of the water. This dilutes the chlorine concentration.
What if I’m sensitive to or allergic to chlorine? Are there any alternatives to keep my pool clean and clear?
Don’t worry, even if you’re sensitive to chlorine or have a chlorine allergy, you can still enjoy a refreshing dip.
• Liquid chlorine alternatives
With Famiflora Always Blue or BSI Poolsan, you can keep your pool water clean without using traditional chlorine. So you won’t suffer from itchy eyes or the strong smell of chlorine.
An additional benefit is their flocculating effect. Organic contaminants, such as sun cream, skin oils and other fine particles of dirt, are aggregated into larger flocs. This makes it easier to filter out the dirt or remove it using a pool vacuum cleaner.
• Saltwater system
You can also choose to maintain your pool using a saltwater system. This is not a replacement for a filter pump, but an additional step. Through electrolysis, this system converts pool salt into natural chlorine, thereby killing algae, fungi and bacteria. This allows you to enjoy a clean pool without the use of chemical chlorine.
Make no mistake: a salt water system is not entirely chlorine-free. This is because it naturally produces chlorine from salt. Would you like to know more about this?
Then be sure to read our FAQ on salt water systems!
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