10 Best Chlorine Tablets of 2021 – Tested & Reviewed

Best Chlorine Tablet
Photo: gettyimages.com

One of the best ways of keeping your pool water clean is by treating it using chlorine. Most people associate this chemical with its unpleasant smell and taste (if you let in some chlorinated water into your mouth).

Despite this, chlorine does a very good job of killing bacteria and other harmful organisms that thrive in the stagnant pool water.

The best way to apply it is in the form of chlorine tablets. However, not all these tablets are the same. For this reason, the review below covers ten of the best chlorine tablets that you can buy online.

Things To Know Before Buying Chlorine Tablets

How to Buy the Best Chlorine Tablet

1. Calculate Chlorine Demand

As the name suggests, chlorine demand refers to the amount of chlorine that your swimming pool needs.

It is important to consider this factor because if you add too much chlorine into your water, it will become cloudy and slightly acidic.

On the other hand, if you treat your pool using a very little amount of chlorine, the bacteria and algae will not be eliminated.

To calculate this demand, you must first get the volume of water in your pool using its length, width, and average depth, then incorporate other variables into the equation such as the water temperature, pH etc.

The best way to determine this demand is by using digital means such as by using a digital meter, which gives you very accurate results. With the value that you will get, buy the appropriate quantity of chlorine tablets that are required.

2. Stabilized or Unstabilized Chlorine Tablets

What is difference between stabilized and unstabilized chlorine tablets?

– Stabilized

Stabilized chlorine is designed to have an in-built resistance towards the sun’s UV rays. Therefore, such tablets will last longer and protect your water for longer in daylight.

For this reason, stabilized chlorine such as Swim Best’s U009050050 is used for most outdoor pools.

– Unstabilized

As the name suggests, unstabilized chlorine is unstable under sunlight and it does so by losing its effectiveness. Therefore, it is only used to treat indoor pools.

3. Dosage and Size

This is a no brainer. The size and dosage of the chlorine tablets bought should be enough for your pool size.

For the dosage, the bigger the pool, the more the quantity of chlorine that it will need and this is usually indicated as a ratio on each product.

This ratio shows the number of tablets required per volume of water, for instance, 3 tablets per 10,000 gallons of water per week.

The higher the dosage, the more the tablets that you will require and therefore, your maintenance costs might be very high.

For this reason, it is important to consider the product with a low dosage such as Clorox Pool&Spa’s 22005CLXW, which has a 1 tablet/10,000 gallons of water dosage, but is still very effective at sanitizing your pool.

When it comes to size, there are two main sizes of chlorine tabs and these are 1 and 3 inches. The size that you buy should depend mostly on the type of dispenser that you use or the volume of your pool.

Small pools, especially the above ground variety, are better to treat using 1-inch tablets like Kem-Tek’s 177 while larger pools ​require large 3-inch tablets like those in In The Swim’s BLZ-5626 so as to cater ​for the big volume of water.

4. Formulation

A chlorine tablet’s formulation is important to consider because it shows you how the specific product is designed to help you.

For instance, some tablets are 4-in-1 (such as HTH’s 41244), which gives you benefits such as algae control, sanitization, prevention of corrosion and removing organic contaminants. 

​Others like Clorox Pool&Spa’s 23025CLX are 6-in-1 formulations, which give you more benefits. Generally, the more the benefits, the better the product.

How to Add Chlorine to Your Pool (Guide)

How to Add Chlorine to Your Pool
Photo: Clorox

Some people think that you simply have to drop in chlorine tablets in your pool for the water treatment to commence. However, it is not that obvious.

Having the chlorine tablets at the bottom of your pool is not very effective, and it also causes staining or bleach liners.

The best way to add these tablets is by using:

1. Floating dispensers

The best thing about floating dispensers is their ease of use. You just have to place a few tablets inside and let it dispense the sanitizer slowly as the tablets dissolve while it floats around the pool.

However, this method also has a few problems because the dispenser is passive. Basically, this means that chlorine is dispensed unevenly as water does not pass through them.

They can also get stuck in one part of the pool and dispense a lot of chemical in that area. This can cause discoloration (bleaching) and even destroy your pool liner if you have one.

Therefore, even though it’s a cheap way to chlorinate your pool, it might not be the best option.

2. The Pool’s Skimmer

With a pool skimmer, you do not have to buy anything else apart from the tablets themselves.

It is a much better way to spread out the chlorine because water is passed through the skimmer basket, dissolving chlorine faster, then the return jets ensure that the chemical is evenly distributed in your pool.

However, when you switch off your pool pump, the tablets will continue dissolving in your skimmer, creating a very high concentration of chlorine that might be corrosive to your equipment.

To deal with this, you can remove the partially dissolved tablets from the skimmer once you switch off the pump or install a variable speed pool pump that will run continuously without consuming large amounts of electricity.

3. An Automatic Chlorinator

This is the best option for sanitizing your pool. You simply have to install the chlorinator just before the return lines from your filtration system, adjust its feed rate, then test the water after some time to ensure that the water contains the right amount of chlorine.

4. Chlorine Granules

This is not a very effective way to treat your water, but it is fast. Basically, you have to crush the tablets into an ash-like substance, then spread it out on your pool.

It can be a perfect method for last-minute water sanitization, but it is not recommended.

10 Best Chlorine Tablets Reviewed




Swim Best U009050050

1. Swim Best U009050050 (Best 3-inch Tablet)

  • 99% Trichloro-S-Triazinetrione with 90% stabilized chlorine
  • 50-pound bucket of 8-ounce, 3-inch tablets
  • Individually wrapped pieces
  • Applicable via skimmers, feeders or floaters
Pool Mate 1-1407

2. Pool Mate 1-1407 (Best 2-in-1)

  • Chlorinates and stabilizes/conditions the water
  • Individually wrapped 3-inch tablets
  • Available in 4, 7, 15- and 50-pound buckets
Robelle 1410M

3. Robelle 1410M (Best 5-in-1)

  • 5-in-1 multi-purpose cleaning function
  • 3-inch, 8-ounce individually wrapped tablets
  • UV stabilized
  • 5, 10, 20- and 40-pound packaging options
Clorox Pool&Spa 23025CLX

4. Clorox Pool&Spa 23025CLX (Best for Swimming Pool)

  • 6-in-1 formulation
  • 3-inch tablets
  • UV stabilized
  • 5, 12, 25 and 35-pound packaging options
Kem-Tek 2815-6

5. Kem-Tek 2815-6 (Affordable)

  • Affordable
  • 95% of Trichloro-S-Triazinetrione
  • Saltwater compatible
  • 1-inch tablets in a 1.5-pound container
In The Swim BLZ-5626

6. In The Swim BLZ-5626 (Individually Wrapped)

  • Individually wrapped tablets
  • 99% Trichloro-S-Triazinetrione with 90% stabilized chlorine
  • 50-pound bucket packaging
  • Thick and UV stabilized
Kem-Tek 177

7. Kem-Tek 177 (Suitable for Salt Pools)

  • Suitable for salt or freshwater pools
  • 95% Trichloro-S-Triazinetrione
  • UV stabilized
  • Slow dissolving with reduced crumbling
NAVA 12000295

8. NAVA 12000295 (Slow Dissolving)

  • Slow dissolving and UV stabilized 3-inch tablets
  • Individually wrapped
  • 25, 50- and 100-pound bucket options
  • 90% chlorine and 99% Trichloro-S-Triazinetrione
Clorox Pool&Spa 22005CLXW

9. Clorox Pool&Spa 22005CLXW (Easy-to-Apply)

  • Applicable via skimmers, feeders or floaters
  • Individually wrapped 3-inch tablets
  • 99% Trichloro-S-Triazinetrione
  • Available in 5, 12, 25- and 35-pound containers
HTH 41244

10. HTH 41244 (4-in-1 Formulation)

  • 4-in-1 formulation
  • 3-inch UV stabilized 8-ounce tablets
  • Dispensable via skimmer, floater or feeder
  • 3.5-pound packaging

1. Swim Best U009050050 (Best 3-inch Chlorine Tablets)

Swim Best Swimming Pool Chlorine Tablet

Photo: Swim Best

If you are looking for the best 3-inch chlorine tablets for your pool, then you should consider Swim Best’s tablets.

This is because each one of them contains concentrated 99% Trichloro-S-Triazinetrione plus 90% stabilized chlorine, which means that it dissolves slowly in your pool water, even under the sun’s UV rays.

In terms of size, this product comes as a 50-pound bucket of chlorine tablets, with each tab weighing 8 ounces. Doing the math, this means you get around 100 tablets, which are quite many and will last for long if you have a small pool.

For safety, each of these tablets is individually wrapped, and this ensures that your garage remains clear of any chlorine fumes, even if you leave the bucket lid open.  

On application, these tablets can be administered to your pool using floaters or stationary feeders such as automatic chlorinators. They can also be applied using a pool’s skimmer, provided that it and the piping to the pump are plastic-made.

On the downside, this product is very expensive, but you get quite a substantial quantity. An important thing to note is that for the best results, always use a test kit to ensure that the chlorine levels are at 1.0-3.0 ppm.


  • Highly concentrated 99% Trichloro-S-Triazinetrione
  • Large quantity (50-pound bucket)
  • Stabilized chlorine makes the tablets last longer under the sun’s UV rays
  • Tablets are individually wrapped for safety purposes and easy handling
  • Can be applied using floaters, feeders or skimmers


  • Expensive
  • Not ideal for saltwater pools

2. Pool Mate 1-1407 (Best 2-in-1 Chlorine Tablets)

Pool Mate Jumbo 3-inch Chlorine Tablet

Photo: Pool Mate

If you want to treat your pool in up to 2 ways, then you should get Jumbo tabs from Pool Mate. This is because the units have chlorine that is used to sanitize water from contaminants such as bacteria and algae.

The tablets also act as stabilizers/conditioners, protecting the chlorine from degradation after being exposed to the sun’s UV rays so that it disinfects for longer, reducing the chlorine demand.

However, you should use a pool test kit to ensure that the stabilizer is kept at 40-100 ppm, chlorine at 2-4 ppm, pH at 7.2-7.6 ppm and total alkalinity at 70-140 ppm so that the tablets give you the best results.

On the packaging, this product is available in 4 different types of container sizes, which include 4, 7, 15- and 50-pound buckets.

Inside each of these containers are 8-ounce tablets that are individually wrapped for safe and easy handling, and should be applied in the ratio of 1-3 tablets per 10,000 gallons of water via a floater or in-line feeder only.


  • Treats pool water in 2 ways (chlorinating and stabilizing)
  • Available in 4 different container sizes
  • Comes as large 3-inch slow-dissolving tablets
  • Each tablet is individually wrapped for safe and easy handling


  • Not ideal for saltwater pools

3. Robelle 1410M (Best 5-in-1 Chlorine Tablet)

Robelle 5-in-1 Multi-Purpose Chlorine Tablet

Photo: Robelle

This is the top-rated chlorine tablet in this review because it gives a 5-in-1 multi-purpose cleaning function, which reduces the number of chemicals you need to maintain your pool.

These functions include water clarification to produce crystal clear water, stain inhibition to prevent and remove stains caused by metals and minerals, algae control, built-in descaler to prevent scale build-up that leads to corrosion and water sanitation.

In terms of size, this specific product comes in a 10-pound bucket containing twenty, 3-inch, 8-ounce, stabilized tablets that are slow dissolving and wrapped individually for easy and safe handling.

However, there is a smaller and cheaper 5-pound bucket that is ideal for smaller pools as well as larger 20- and 40-pound options for larger pools. This is because the treatment ratio is 1-3 tablets per 10,000 gallons of water and therefore, the bigger the pool, the more the tablets you will need.


  • Contains a proprietary blend that gives you a 5-in-1 multi-purpose cleaning function
  • Large 3-inch, 8-ounce tablets
  • Stabilized and slow dissolving tablets for prolonged treatment
  • Tablets are wrapped individually for easy and safe handling


  • Comes in a relatively small 10-pound bucket, but there are larger, more expensive options
  • Not ideal for saltwater pools

4. Clorox Pool&Spa 23025CLX (Best Chlorine Tablet for Swimming Pool)

Clorox Pool&Spa Xtra Blue Chlorine Tablet

Photo: Clorox

Clorox’s pool & spa chlorine tablets are the best pool cleaning tablets in this review because they have a 6-in-1 formulation that gives you a huge advantage in the maintenance of your pool.

This formulation basically controls algae growth, kills bacteria, prevents corrosion from scale build up, removes organic contaminants for clearer water, makes water silky smooth and protects chlorine in the water against sunlight so that it is sanitized for longer.

However, for the best results, it is important to test and balance the water before application, which means that you have to use a test kit to measure the pH levels, alkalinity, and other water quality tests.

On matter size, each of the tablets is 3 inches wide and long-lasting, meaning that your pool will be sanitized for longer, even with exposure to sunlight.

Other features include 5, 12, 25 and 35-pound packaging options but the tablets are not wrapped individually, which makes it a bit difficult and unsafe to handle them.


  • UV stabilized tablets with a 6-in-1 formulation
  • Controls algae growth
  • Prevents corrosion from scale build up
  • Makes water silky smooth
  • ​available in 4 packaging options


  • Tablets are not individually wrapped

5. Kem-Tek 2815-6 (Most Affordable)

Kem-Tek 2815-6 Chlorine Tablet

Photo: Kem-Tek

For affordability, Kem-Tek’s 2815-6 takes the lead. This though does not mean that it is a low-quality product. In fact, its low price is mostly due to its size, in which it comes in a small 1.5-pound container.

Because of this economical size, these are the best chlorine tablets for above ground pools as well as pop up pools that are small in size.   

Each tablet in the container is 1 inch in size and this means that you may have to use more of them as compared to the larger 3-inch tablets in other products.

In terms of application, these 1-inch units can be administered to your pool using the skimmer, floater or feeder, and since each contains stabilized chlorine, it works for up to a week while dissolving slowly and being very effective under the sun’s UV light.

Other features include being salt water system compatible and containing 95% of Trichloro-S-Triazinetrione.


  • Very affordable
  • Can be applied using a skimmer, floater or feeder
  • Stabilized and thus, it lasts longer (for up to a week) even under the sun’s UV light
  • Saltwater-system compatible
  • Contains 95% Trichloro-S-Triazinetrione, which is still very concentrated


  • Comes in a very small quantity (1.5 pounds)
  • Tablets are not wrapped individually

6. In The Swim BLZ-5626 (Individually Wrapped)

In The Swim 3-inch Pool Chlorine Tablet

Photo: In The Swim

In The Swim’s 3-inch chlorine tablets are quite similar to Swim Best’s product above, coming as individually wrapped pieces that are safer to handle because they won’t leave any chlorine fumes when stored.

These tablets are packaged in a 50-pound bucket and with each weighing 8 ounces. This gives you about 114 tabs per bucket, which are quite a lot, especially considering that the required dosage is approximately 1-2 tabs per 10,000 gallons of water per week.

On chemical composition, the tablets contain a powerful and concentrated 99% Trichloro-S-Triazinetrione and 90% stabilized chlorine, making them very effective.

They are also thicker than other pool chlorine tablets and combined with their stabilized chlorine composition, they dissolve very slowly, even in outdoor pools under the sun’s UV rays. This means that your pool is protected from bacteria for longer periods of time.

On application, these units are just the ideal size to use in floaters, skimmers or automatic feeders (such as chlorinators) and should be applied in the ratio given above per week.

On the downside, this product is also quite expensive, but you also get a sizeable quantity to use for a long time.


  • Individually wrapped tablets for safety and convenience
  • Comes in a large 50-pound bucket
  • Gives you about 114 tabs per bucket
  • Concentrated 99% Trichloro-S-Triazinetrione
  • Thicker than other chlorine tablets and contains 90% stabilized chlorine, making it dissolve slowly and last longer


  • Relatively expensive
  • Not ideal for saltwater pools

7. Kem-Tek 177 (Salt System Compatible)

Kem-Tek 177 1-inch Chlorine Tablet

Photo: Kem-Tek

Kem-Tek is known to produce salt water compatible chlorine tablets and this 177 is no different. The product can also be used in freshwater pools, making it very versatile in terms of use.

On size, this product comes in a small but affordable 4-pound container, although there are larger but costlier 15- and 24-pound options. The tablets themselves in these containers are also small in size, measuring only 1-inch.

Despite this small size, these tablets are very effective at sanitization and algae control and are stabilized so as to reduce chlorine loss from the sun’s UV rays. They are also manufactured to reduce crumbling because of their small size.

Other features include being slow dissolving (enabling it to chlorinate for up to a week), containing 95% Trichloro-S-Triazinetrione and requiring a floater or feeder for the application.


  • Ideal for use in ​salt or freshwater pools
  • Sanitizes and controls algae growth
  • Tablets are manufactured to reduce crumbling
  • Slow dissolving and stabilized tablets


  • Small 1-inch tablets
  • Tablets are not wrapped individually

8. NAVA 12000295 (Slow Dissolving)

NAVA Chlorine Tablet for Swimming Pool/Spa

Photo: NAVA

Nava chlorine tablets are slow dissolving pool tablets that are designed to release their 90% chlorine and 99% Trichloro-S-Triazinetrione active chemical ingredients gradually to sanitize your water for a long time.

On top of this, the tablets are stabilized, reducing chlorine loss from the sun’s UV rays, which reduces chlorine demand.

Size wise, each of these tablets is 3 inches wide and is individually wrapped for easy and safe handling. On the container, this product comes in a 50-pound bucket, which is quite expensive, but you get a lot of tablets for long term treatment.

However, there is a smaller and cheaper 25-pound bucket option, as well as a larger 100-pound bucket that you can consider if you have the money or if you have an extremely large pool to maintain.


  • Slow dissolving 3-inch chlorine tablets that remain effective for a long time
  • Stabilized to ensure they reduce chlorine loss from the sun’s UV rays
  • Tablets are wrapped individually for easy and safe handling
  • Available in multiple container sizes with different tablet quantities


  • Relatively expensive

9. Clorox Pool&Spa 22005CLXW (Easy-to-Apply)

Clorox Pool&Spa Active99 Chlorine Tablet

Photo: Clorox

These Active99 chlorine tablets are easy to apply because you can use a floater, feeder or skimmer to dispense them.

The recommended dosage is 1 tablet per 10,000 gallons of water until you get it to 1-4 parts per million. This, of course, needs a pool test kit to confirm these quantities.

For easier handling when doing the application, each of the tablets is individually wrapped, and this also makes them safer to handle because chlorine is quite toxic, especially when concentrated.

Apart from the 5-pound bucket, the Active99 is available in various container sizes, including 12, 25- and 35-pound buckets, and 12- and 25-pound options with 6-pound shocks and a 35-pound bucket with a 12-pound shock.  

Regardless of the size of the pack, each one has 3-inch tablets containing a concentrated 99% Trichloro-S-Triazinetrione for effective bacteria and algae killing.


  • Easy to apply using floaters, feeders or skimmers
  • Individually wrapped tablets for easy and safe handling
  • Available in various container sizes for different pool sizes
  • Large 3-inch tablets with a concentrated 99% Trichloro-S-Triazinetrione


  • Comes in a small 5-pound container, though there are larger but more expensive options

10. HTH 41244 (4-in-1)

HTH 41244 Ultra Chlorine Tablet

Photo: HTH

If you would like to treat your pool in 4 different ways, then HTH’s 41244 is a good option to consider. This is because the product contains active chemical ingredients that fight algae, clarify the water, prevent staining and softens the water.

However, the tablets come in a small 3.5-pound bottle containing only a few 8-ounce chlorine tablets that are enough for small pools.

On the bright side, each tablet is 3 inches in size and is stabilized so that it has a built-in resistance towards sunlight. This makes the chlorine last longer for up to a week of sanitization.

In terms of application, this unit can be administered using your pool’s skimmer, as well as using a floater or feeder.   


  • 4-in-1 formulation
  • UV stabilized ​
  • Large 3-inch size
  • Can be dispensed via a skimmer, floater or feeder. ​


  • Comes in a small quantity (3.5 pounds)


In conclusion, chlorinating your pool is very vital to maintaining clean and healthy water, but you must use the best chlorine tablets.

With that in mind, Clorox Pool&Spa’s 23025CLX stands out as the overall best because of its 6-in-1 formulation, which is very effective at cleaning and sanitizing your pool.