Keeping your pool sanitised is vital if you want to make your pool a safe space for swimming for yourself and your family. Chlorine is the sanitiser of choice for most pool owners. However, the majority of pool owners prefer using chlorine in granular form. Typically, the chlorine is dissolved in a bucket of water before being introduced to the pool. After it enters the pool, it eliminates microorganisms and sanitises the pool.
Key Takeaways
- Pool chlorine tablets dissolve slowly, helping maintain a steadier chlorine level than “fast-hit” granular doses.
- “Stabilised” tablets (with cyanuric acid) are usually better for outdoor pools because sunlight burns off unstabilised chlorine faster.
- The “best” way to dose is controlled and consistent: an automatic chlorinator is the most precise, while floating dispensers can over-concentrate chlorine in one area.
- Don’t throw tablets directly into the pool — they can sit on the surface/floor and cause damage.
- Tablet dosing depends on pool volume; use the chart as a starting point and confirm with regular testing (chlorine + pH).
- If you rely heavily on stabilised tablets long-term, keep an eye on stabiliser (cyanuric acid) because it can build up and reduce chlorine effectiveness.
How chlorine works to sanitise a swimming pool
Before we get to the details of chlorine tablets, we feel it’s important to tell you how chlorine works in a pool. Well, this is how – when you introduce chlorine to your pool water, a chemical reaction takes place over time. During this chemical reaction, two compounds – hypochlorite ions and hypochlorous acid, are formed.
After the formation of these compounds, they proceed to oxidise all the contaminants present in the pool water. However, their speed of action differs. On one hand, there’s hypochlorous acid, which begins to sanitise the water as soon as it’s formed. On the other, there are hypochlorite ions, which are released much more slowly compared to hypochlorous acid.
In simple terms: chlorine doesn’t just “sit” in the water — it actively reacts with contaminants (like sweat, sunscreen, and organic debris) and helps kill germs. The more contamination and the hotter/ sunnier the conditions, the harder chlorine has to work. That’s why steady dosing (which tablets are good at) plus regular testing is the real secret to consistently clear, safe water.
For home pools, common guidance is to keep free chlorine at least 1 ppm (often 1–4 ppm depending on conditions/product guidance) and pH around 7.0–7.8.
Why consider chlorine tablets
Now that you’re aware of how chlorine works in a swimming pool, let’s move on to chlorine tablets. You’re probably wondering at this point why you should consider chlorine tablets when chlorine is so readily available in granular form. Well, we recommend using chlorine tablets for pool sanitisation if convenience is your priority.
For starters, chlorine tablets don’t have to be measured in the way you’d have to measure chlorine in its granular form. As you might know already, too little or too much chlorine can disrupt your pool water chemistry. So, when using chlorine in its granular form, you’ve got to be incredibly careful, and measuring it properly can take some time.
Chlorine tablets are also known for their gradual dissolution in pool water. So, they can be more effective in terms of sanitising the pool than granular chlorine, which is much more fast-acting. However, this doesn’t mean you can throw caution to the wind when using chlorine tablets. You’ve still got to take care as too much chlorine in a swimming pool is never a good thing.
Pool chlorine tablets vs granular chlorine (what’s different?)
Granular chlorine is often used when you need a quicker correction (for example, if your chlorine has dropped and you need to bring it up promptly). Tablets/pucks are more of a maintenance-style option: they dissolve over time and help keep your chlorine level steadier between tests. Many pool owners use a combination approach: tablets for “baseline” sanitation and another chlorine format when they need faster adjustments (always following product instructions).
One important note: many common tablet products are “stabilised,” meaning they contain cyanuric acid (stabiliser). This can be helpful outdoors, but it’s something to monitor over time.
Chlorine tablets: The different types
The differences between the various chlorine tablet products in the market are on the basis of their:
Ingredients: When shopping for chlorine tablets, you’ll see some products labelled as ‘stabilised’ and others as ‘unstabilised’. The difference between stabilised and unstabilised chlorine is simple – stabilised chlorine contains a chemical called cyanuric acid, while unstabilised chlorine doesn’t contain this chemical. Cyanuric acid prevents the sun’s UV rays from damaging the chlorine, which is why stabilised chlorine products are recommended for outdoor pools. If you want to use unstabilised chlorine tablets for your outdoor pool, you’d have to do it in the evening. However, you can feel free to use unstabilised chlorine tablets for your indoor pool at any time of the day.
Size: You can either buy 1-inch chlorine tablets or 3-inch variants. The difference between the sizes lies essentially in their chlorine content. The chlorine content in 1-inch chlorine tablets is less than half of the chlorine content in 3-inch variants. This makes them ideal for small spas and pools. However, if you have a big swimming pool, investing in the 3-inch variants would make more sense as a single 3-inch chlorine tablet can be used for treating up to a whopping 5,000 gallons of water.
What chlorine tablets are best for a pool?
“Best” depends on where your pool is and how you manage water balance:
- Outdoor pools: stabilised tablets are commonly preferred because sunlight can break down chlorine quickly.
- Indoor pools: unstabilised tablets can be perfectly suitable because UV loss is much less of a factor.
- If your stabiliser (CYA) is already high: you may want to reduce reliance on stabilised tablets and talk to your pool professional about options, because CDC notes that products with cyanuric acid (like common dichlor/trichlor products) change recommended minimum free chlorine needs.
Are all chlorine pucks the same?
Not always. Even if they look similar, tablets can differ by: stabilised vs unstabilised chemistry, percentage of available chlorine, additives, and intended dosing method (some products explicitly warn against skimmer use).
What's the best way to add chlorine tablets?
There are a few options to consider in terms of adding chlorine tablets to your swimming pool:
Via the pool skimmer: Putting the chlorine tablets in the pool skimmer and then running the pump is a great way to distribute the tablets evenly throughout your pool. The greatest advantage of using the pool skimmer to distribute the chlorine tablets is that you only need to purchase the tablets – no additional equipment is necessary!
Via a floating dispenser: You can also use a floating dispenser to distribute the chlorine tablets throughout your pool. However, we recommend against using a dispenser as it can get stuck, and if it does, it’ll end up distributing the chlorine in only a few areas of the pool. So, if you want even pool chlorination, steer clear of floating dispensers.
Via an automatic chlorinator: If you want maximum control over things like how fast the chlorine should dissolve and how much of it should enter your pool, invest in an automatic chlorinator. Sure, it’ll involve a high upfront expense, but it’ll be worth it in the long run. To make it work, simply fill it with the chlorine tablets and set it according to your preferences. If you don’t have the time to manually add chlorine to your swimming pool, this option is your best bet.
Does chlorine damage fibreglass pools? See the details here!
Alternatively, you can also crush the tablets and turn them into powder. However, if you plan on doing this, why not buy chlorine in its granular form? Also, be sure to steer clear of throwing the tablets into the water directly. This will lead to the tablets eventually settling at the bottom of your pool, where they’ll slowly dissolve and wreak havoc on the masonry.
How many tablets should you add?
The following dosage chart should help you add the right amount of chlorine tablets:
- 1 tablet every week for pools with capacities of 2,500 – 5,000 gallons
- 1 – 2 tablets each week for pools with a capacity of 7,000 gallons
- 2 tablets each week for pools with a capacity of 10,000 gallons
- 2 – 3 tablets each week for pools with a capacity of 13,500 gallons
- 3 tablets each week for pools with capacities of 15,000 – 17,000 gallons
- 3 – 4 tablets each week for pools with a capacity of 20,000 gallons
- 4 – 5 tablets each week for pools with a capacity of 25,000 gallons
- 5 – 6 tablets each week for pools with a capacity of 30,000 gallons
Conclusion
So, we hope this article proved to be informative in terms of letting you understand the ins and outs of chlorine tablets. Now, you should be able to add chlorine tablets to your swimming pool by yourself without any fuss or bother.
Frequently Asked Questions
What chlorine tablets are best for a pool?
For most outdoor pools, stabilised tablets are commonly preferred because UV can burn off unstabilised chlorine faster. If you’re managing high stabiliser (CYA) already, you may need to rethink heavy tablet reliance and adjust testing/targets accordingly.
How many chlorine tablets should I put in my pool?
Use the article’s dosage chart as a starting point based on pool volume, then fine-tune based on testing results (sun, swimmers, and storms change demand).
Are chlorine tablets good for your pool?
Yes—when used correctly. Tablets are convenient and dissolve gradually, which helps maintain a more consistent chlorine level. The key is dosing properly and avoiding direct contact with pool surfaces.
Are all chlorine pucks the same?
No. They can differ by stabilised vs unstabilised chemistry, strength, and usage warnings (some products specifically warn against skimmer placement).
Can I put pool chlorine tablets in the skimmer?
Some pools do, but many tablet products and pool pros warn against it because concentrated chlorinated water can pass through equipment/plumbing—especially if the pump is off. Follow the product label; a chlorinator is often the safer controlled option.
Can I throw chlorine tablets directly into the pool?
No—avoid it. Tablets can settle and dissolve slowly in one spot and cause surface damage. Use a feeder/chlorinator (preferred) or other method that prevents direct surface contact.
Do chlorine tablets increase cyanuric acid (stabiliser)?
Many common tablet products are stabilised and contain cyanuric acid; over time this can build up and affects chlorine effectiveness and recommended minimum chlorine levels.