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6 Best Chlorine Tablets for Swimming Pools | Reviews & Buyer’s Guide

Every avid swimmer knows that to keep their swimming pool safe, they need to chlorinate it on a regular basis. Chlorine is that crucial element in a pool that gives the pool water its unique taste and smell.

Best Chlorine Tablets

Why do you need to add chlorine to your swimming pool? Chlorinating your pool is necessary to keep the pool water clean and your family healthy. It is one of the best possible ways to kill all the bacteria, viruses, and protozoa in stagnant water. When it comes to adding this chemical to the water in your swimming pool, the most convenient way is through chlorine tablets.

Chlorine tablets essentially help prevent the formation of algae, keep the pool walls and the pool floor free from any stains, and remove the odor that could form otherwise in your pool.

Of course, not all chlorine tablets are made the same. It is necessary to add chlorine tablets to the pool water from time to time, but you cannot just pick out any random packet and throw it into your swimming pool. With so many products out there in the market, you need to choose the right one.

The overabundance of chlorine tablets can make it quite difficult for a person to decide which one they should get, especially if they do not have any experience in maintaining their swimming pool (which a lot of swimming pool owners don’t).

We have come up with this guide to help you select the right chlorine tablet that you can use for your pool. In the guide, we have listed down and reviewed some of the best chlorine tablets in the market and discussed all the important factors that will help you make the best possible buying decision.

Let us get started with the list of reviews for the best chlorine tablets that you can get for your pool.

Best Chlorine Tablets

Here's the list of the 6 best chlorine tablets for swimming pools, carefully reviewed and selected to help you make the best buying decision for your pool.

1. In The Swim 3 Inch Pool Chlorine Tablets 50 lbs - Best for Long-lasting Chlorination

Our top pick for the best chlorine tablets you can get for your swimming pool is this product by In The Swim. These 3-inch pool chlorine tablets are very powerful and stabilized. The dosage is perfectly proportioned in a way that two tablets can easily chlorinate every 10,000 gallons of water for a week.

In The Swim 3 Inch Stabilized Chlorine Tablets for...
  • Eliminate bacteria, algae, and other organic contaminants,...
  • 99% Trichloro-S-Triazinetrione and 90% available stabilized...

We like this because these three-inch tablets come in a package that contains 50 pounds worth of tablets. If you are going to need to use just a few every week, you will have plenty of chlorine tablets to last you through the summer and beyond. With 114 tablets in a bucket, their effectiveness does depend on the temperature of the pool and the sunlight.

The In The Swim 3 Inch chlorine tablets are advertised as the longest lasting tablets that take their time to dissolve. These tablets are all individually wrapped in the packaging to make sure that they are protected. The buckets they come in are waterproof, locked safely, and quite strong. You can rest assured that all the tablets will be safe in there during the time they are stored away. As a safety measure to ensure you do not get any chlorine dust on your hands, the individually wrapped chlorine tablets are also packed inside a plastic bag before they go into the bucket.


  • The tablets dissolve slowly and last long
  • They offer a good job and are affordable tablets
  • These tablets are well protected


  • Some customers found the tablets too fragile
  • A lot of customers found the individual wrapping on the tablets annoying

Form: Tablet | Dimensions: 20 x 13 x 13 inches | Weight: 55 pounds | Dosage: 2 tablets per 10,000 gallons | UV Protection: No

2. In The Swim Chlorine Pool Shock 24 x 1 lb. Bags - Best for Quick Pool Cleaning

For someone looking for a quick solution to cleaning their swimming pool and has a lot of algae to deal with, the best way to go is through pool shock. In The Swim does not just create chlorinating tablets, they cater to the needs of pool owners when it comes to shocking the pool as well.

In The Swim Pool Shock – 68% Cal-Hypo Granular Sanitizer...
  • Powerful chlorine shock treatment that is great for regular...
  • Quickly eliminates algae, bacteria, and other harmful...

The In The Swim Chlorine Pool shock is one incredibly effective way of clearing up the pool of bacteria and algae in very little time. This is a reliable and easy to use product, which also happens to be one of the more affordable ones that we have reviewed in the guide. This product features an active ingredient called Potassium Mono Persulfate. Comprising about half the quantity of each 1 pound packet, the Potassium Mono Persulfate helps the pool shock quickly kill the harmful bacteria and algae in the pool water.

The shock performs even better in a pool that has been treated with bromine. It also removes dead chlorine cells to provide a chlorine-free reading. The product shocks your pool and improves the condition of the water to make it safer for you and your family to swim in.


  • Prevents the growth of algae and bacteria in the pool
  • Does a very quick job of cleaning the pool
  • Performs even better when used in a sanitized pool


  • Does not make any improvement on the chlorine levels in swimming pool
  • Some customers have complained that it clouds up their pool sometimes

Form: Granular | Dimensions: 11.3 x 11.3 x 10.4 inches | Weight: 27 pounds | Dosage: 1 lb. per 10,000 gallons | UV Protection: No

3. Clorox Pool and Spa Active99 - Best for Continuous Pool Use

If you are looking for a product that will clean your pool and allow you to use it 24/7 without any problems, the Clorox Pool and Spa might be the one for you. This product consists of 3-inch chlorine tablets that are stabilized for a longer lasting performance in the pool.

Clorox Pool&Spa Active99 3” Chlorinating Tablets 5 lb.
  • 99% Trichloro pool chlorine tablet that maintains a healthy...
  • Kills harmful bacteria

The stabilized tablets are able to resist disintegration due to harmful UV rays. Each of the tablets comes wrapped individually to make sure that you are as safe as possible from the risk of chlorine dust when the time comes to open them up and put them into the pool. Designed for use every week, you can add them to your swimming pool through a floater, feeder, or skimmer to make sure your pool water remains fresh and safe.

One of the features we really like about the Active99 Chlorinating Tablets by Clorox is the Trichloro-S-Triazinetrione. You need to be very careful when adding them to the pool because contact with your skin or eyes can cause a lot of irritation. They are very powerful chlorinating tablets.


  • Resistant to the effects of UV rays from the sun
  • They effectively kill algae and bacteria in the water
  • They improve the condition of the swimming pool


  • You need to be very careful when adding them to the pool
  • They are not very effective against black algae

Form: Tablet | Dimensions: 7.68 x 9.8 x 6.43 inches | Weight: 5 pounds | Dosage: N/A | UV Protection: Yes

4. RX Clear 99%

RX Clear is one of our favorites in terms of getting the best value for your money when it comes to chlorinating tablets. While chlorinating tablets are never prohibitively expensive, there are some that give you more for your money than others, and the RX Clear 99% is one of them.

Rx Clear Stabilized Granular Chlorine | One 50-Pound Bucket...
  • CLEAR WATER FOR SAFE SWIMMING - Swimming in crystal clear...
  • LONG LASTING - Dichlor resists UV light, lasting longer than...

This product contains sodium-stabilized chlorine in a granular form. The 50-pound bucket will last you a whole season so you will not have to bother with visiting the market again and again to get chlorine for your swimming pool. The chlorine is 90% and the Trichloro-s-triazinetrione is 99% to make sure that this is some of the best concentrations in the products of this category in the market.

Each of the tablets is wrapped individually to offer safer use and better protection for your hands as you add them to the pool.


  • Packing is well done
  • Very easy-to-use chlorinating tablets
  • This product is safe to use for your swimming pool


  • The tablets do not feature UV protection
  • The chlorinating tablets do not last very long

Form: Granular, Tablet | Dimensions: 18 x 13 x 13 inches | Weight: 50 pounds | Dosage: 1 ounce per 5,000 gallons | UV Protection: No

5. Clorox Pool & Spa 3-Inch Tablets

Clorox is a brand that is renowned for making products for household cleaning. That well-earned reputation for the manufacturer extends to the products this company makes for keeping the swimming pool clean. The Clorox Pool and Spa 3-inch tablets in 25-pound packaging are very good for above ground and in-ground pools.

Clorox Pool&Spa Active99 3” Chlorinating Tablets 25 lb.
  • 99% Trichloro pool chlorine tablet that maintains a healthy...
  • Kills harmful bacteria

The Clorox tablets all come individually wrapped inside the bucket which preserves their condition and makes them safe to use when the time comes to add them to the pool. They are very effective at killing algae and bacteria in the pool water. They also prevent the growth of bacteria in the long run by stunting their growth right from the start.

While they come individually wrapped, the tablets can become slightly damaged and you need to be careful about the chlorine dust when you are adding them to the water. Make sure you wear the right protection before you add these to the swimming pool.


  • They are very effective at cleaning the pool
  • Each tablet lasts a very long time
  • Has an excellent absorption rate


  • Some customers found them too easy to crumble
  • You need to take extra safety measures because of chlorine dust

Form: Tablet | Dimensions: 9.38 x 13.5 x 10.5 inches | Weight: 25 pounds | Dosage: N/A | UV Protection: No

6. Dry Tec Calcium Hypochlorite Shock

Whether you are looking for a pool shock solution for your in-ground pool or for your above-ground pool, this pool shock might just be something you need for your swimming pool. A lot of people opt for non-chlorinating pool shock and use them with chlorinating tablets separately, but Dry Tec Calcium Hypochlorite Shock allows you to get the effects of both in one product.

DryTec 1-1901-24 Calcium Hypochlorite Chlorine Shock...
  • 24 bags (1-pound each)
  • Fast-Acting Quick-Dissolving Swimming Pool Sanitizer

The Dry Tech pool shock is a fast and active chlorinating shock, which is able to kill off bacteria in your pool. It is also very effective against algae and it eliminates organic contaminants from the pool water. The 68% calcium hypochlorite works very fast to improve the conditions of your swimming pool’s water and raises the chlorine levels very fast.

The only problem you might face with this is the fact that you would need to get a whole bag of the product for every 10,000 gallons. If you have a large pool, you might be using quite a few of these, but you will get a clean pool immediately. For people who do not have the patience for slow-dissolving tablets, this is the perfect product.


  • Fast-acting pool shock
  • Chlorinates as well as shocks the pool
  • Suitable for pools of all sizes


  • You need to use several packets at the same time
  • Does not dissolve particularly well

Form: Granular | Dimensions: 24 x 12 x 6 inches | Weight: 24 pounds | Dosage: 1 pound per 10,000 gallons | UV Protection: No

Best Chlorine Tablets Comparison Table

ProductFormDimensionsWeightDosageUV Protection
In The Swim 3 Inch Pool Chlorine TabletsTablet20 x 13 x 13 inches55 pounds2 tablets per 10,000 gallonsNo
In The Swim Chlorine Pool ShockGranular11.3 x 11.3 x 10.4 inches27 pounds1 lb. per 10,000 gallonsNo
Clorox Pool and Spa Active99Tablet7.68 x 9.8 x 6.43 inches5 poundsN/AYes
RX Clear 99%Granular, Tablet18 x 13 x 13 inches50 pounds1 ounce per 5,000 gallonsNo
Clorox Pool & Spa 3 Inch TabletsTablet9.38 x 13.5 x 10.5 inches25 poundsN/ANo
Dry Tec Calcium Hypochlorite ShockGranular24 x 12 x 6 inches24 pounds1 pound per 10,000 gallonsNo

Buying Guide For The Best Chlorine Tablet

As you can see from the above list of the best products, there are a lot of differences in chlorine tablets. This is why we are going to take a look at a few factors that you need to consider when you are searching for the best chlorine tablets to use in your pool.

What are Chlorine Tablets?

Before you take a look at those factors, it will help to understand exactly what it is that you are using for your pool’s maintenance. Just as the name suggests, chlorine tablets contain chlorine, but they also contain a host of other chemicals that help the chlorine do its job.

This mixture of chlorine disinfects your pool and kills off algae, bacteria, viruses, and any other contaminants in the water. Impurities and contaminants in the water do not just make your pool look dirty; they are an active threat to your health and safety. As chlorine tablets release chemicals into the water and prevent these contaminants from spreading, you can enjoy a safe swim all year long.

How Much Chlorine Should You Use?

The amount of chlorine you need depends on the size of the pool, how much debris you get in the pool, and the type of pool you have. Typically, the right amount of chlorine tablets depends on the gallons that your swimming pool can hold. The general rule is that a single tablet can cater to the chlorinating needs of 5,000 gallons.

One thing you should always do is round off the number of gallons you are adding to the next 5,000 when you add the chlorine tablets. For instance, if your pool has 16,000 gallons, add four tablets to it or the amount equivalent for 20,000 gallons. If it is 15,000 gallons, add three tablets. This way, you will not have less chlorine per gallon in the swimming pool.

What is the Best Time for Chlorination?

The best time to chlorinate the pool is in the evening or at night. The basic reason behind this is that chlorine will get plenty of time to do its job and eliminate bacteria and algae in the pool. If you add chlorine during the day, the sun may interact with it and cause the tablet to dissolve faster. This means it will not get the kind of time it needs to do an effective job.

If you happen to have an indoor pool and the pool water is safe from exposure to UV rays, you can add chlorine tablets at any time of the day.

Chlorine safety and precautions

One thing you need to make sure is that you take as many safety precautions as you can when you are using chlorine tablets. These tablets contain a mixture of different chemicals that need to be stored properly and used with caution.

Make sure that the tablets are stored in a cool and dry place with proper ventilation. If chlorine is exposed to the likes of chlorine or even liquid chlorine, it can result in the release of a lot of harmful gases. In some cases, it can even cause explosions. If the chlorine tablets come into contact with moisture or dirt, they can lose their effectiveness.

Making sure that the chlorine tablets are stored safely is one thing. You should also keep a few more things in mind so you can use them safely:

  • Do not mix the chlorine tablets with other types of chlorine
  • Avoid mixing them with any other types of chemicals
  • Chlorine can be deadly if ingested, so make sure you do not eat any of these tablets
  • Store them somewhere out of the reach of children and pets
  • If you ever see chlorine fumes coming out of the  tablets, take them outdoors and avoid inhaling the fumes
  • Use gloves whenever you are handling chlorine

Why You Should Not Add Chlorine Tablets to a Skimmer

While a lot of manufacturers advertise that you can use the chlorine tablets they make with your skimmer to add it to the pool, it is best to avoid doing that. While using the skimmer can make it a lot easier to add the chlorine, it can cause a major problem for pool water and you, as a result of that.

If you put the chlorine tablets in the skimmer, they will enter the pump and the filtration system. When you turn the pump and water filter off, the tablets will start to dissolve within the skimmer. This can result in highly acidic water which can go into the filter when you turn the pool’s pump back on.

The acidic water can damage the filter drastically. This can cause the filter to malfunction or stop working entirely.

What is the best way to chlorinate your swimming pool?

Instead of trying to use your skimmer to chlorinate your pool, it is always a better idea to use a chlorinator. You can preset the chlorinator to release the chlorine gradually into your pool as time passes. A chlorinator can work with the existing pump and filter in most pools and you can install it without a hassle.

The best thing about an automatic chlorinator is the fact that it can ensure an even distribution of chlorine throughout the water in your swimming pool. The only thing which swimming pool owners might not like about chlorinators is that they have quite a price tag on them.

For someone who does not want to invest a lot of money in a chlorinator, a more affordable alternative is a floating chlorinator or a floater. It is a simple plastic vessel that floats on the pool and releases chlorine into the water. While it is not as effective as evenly distributing the chlorine, it costs a lot less and it is easier to use.

If you do not want to spend any money at all on something to help you chlorinate the pool water, you can just drop the tablets into the pool. Just make sure that you drop the tablets to the point where the water returns into the pool, so you can avoid any damage to the filter and other water circulation equipment.

Calculate Chlorine Demand

Now that you have an idea of how to safely use chlorine tablets, here is a look at the factors which can help you decide which one to go for. The first thing we are going to take a look at is calculating the chlorine demand. Chlorine demand is the amount of chlorine your swimming pool needs to stay clean.

If you add too little chlorine, the bacteria and algae won’t be eradicated. Adding a lot of chlorine means a higher cost and it can make your pool water cloudy. Exceptionally high levels of chlorine in the pool water can also damage the sensitive pool circulation equipment.

Understanding how much chlorine you should add to your pool is very important. The shape and the size of the pool are important factors but the amount of water in the pool is the main determining factor. There are a lot of ways you can calculate the chlorine demand. The best thing to do is to invest in a high-quality digital meter that will give you the exact reading to ensure you get the chlorine amount right.

Stabilized vs. Unstabilized Chlorine Tablets

There are mainly two types of chlorine tablets in the market: stabilized and unstabilized. The stabilized chlorine tablets last a lot longer and dissolve slowly. Some can last long even when they are exposed to the UV rays from sunlight. They are able to perform better in the sun and that is why stabilized chlorine tablets are more suitable for outdoor pools. They are equally effective when it comes to catering to both above-ground and in-ground pools.

Unstabilized chlorine tablets are ideal when you need to chlorinate small pools or hot tubs. They are also very good for indoor pools that are covered. Since they are unstabilized, these chlorine tablets dissolve a lot faster and they can lose their impact if they are exposed to the UV rays in sunlight.

Understanding the Chemistry

As annoying as it might feel, it is a good idea to freshen up your chemistry. The major ingredient in most of the chlorine tablets on the market is trichloro-s-triazinetrione. Most manufacturers, of course, combine a host of other chemicals with the trichloro-s-triazinetrione so that they can increase the effective lifespan of the tablets. The chemical mixture is also able to help the tablets fight algae more effectively.

The mixture of chemicals is designed to increase the lifespan of the tablets by slowing down the rate with which they dissolve. Some of these slow down the rate of chlorine release so much that their overall effectiveness is a lot lower than what you need. This means you might have to use a higher number of tablets to bring the chlorine levels up to a desirable level.

It is not easy to understand the exact balance that you need to maintain. In order to make it easy to understand, think of it like this: If your pool stays clean for most of the time, you should go with high trichloro-s-triazinetrione concentration tablets. If your pool has a lot of algae formation and other issues, you should go with chlorine tablets that have a greater quantity of algae-fighting additive chemicals.

Price vs. Quantity

Most of the chlorine tablets you can get are pretty reasonably priced. Of course, the overall cost of maintaining your pool can be very high. The reason for that is, so many aspects come together to make sure that your pool is well-maintained and safe.

It makes sense to save even a few dollars if you can. When you do that, it will bring down the overall cost of maintaining your pool. We have made the best possible effort to include cost-effective chlorine tablets in the list of reviews for this guide. This means if you go with any of these, you can have the added peace of mind that you will not be spending too much.

You should still make it a point to compare the prices and the quantity being offered of each product. This is because some manufacturers offer higher quantities than others do. This can make comparison slightly difficult.

Chlorine Tablet FAQs

  • How much chlorine should you use?

    The amount of chlorine tablets to use depends on the size of your pool and its capacity in gallons. As a general rule, one chlorine tablet can cater to the chlorinating needs of 5,000 gallons of water. Round up the number of gallons to the nearest 5,000 when adding tablets to ensure proper chlorine levels.

  • What is the best time for chlorination?

    It is best to chlorinate your pool in the evening or at night. Adding chlorine during the day may result in faster dissolution due to sunlight, reducing its effectiveness. However, if you have an indoor pool or a pool protected from UV rays, you can add chlorine tablets at any time.

  • What is the best way to chlorinate a swimming pool?

    Instead of using a skimmer, it is recommended to use a chlorinator, which can be preset to release chlorine gradually into the pool. A chlorinator ensures even distribution of chlorine throughout the water. Alternatively, you can use a floating chlorinator or drop the tablets directly into the pool, making sure they are added at the point where the water returns to avoid damaging the filter and circulation equipment.

  • How can you calculate the chlorine demand for your pool?

    Calculating the chlorine demand is important to determine the right amount of chlorine for your pool. Factors such as pool size and shape influence chlorine demand. Using a high-quality digital meter can provide an accurate reading and help you determine the correct amount of chlorine.

  • What is the difference between stabilized and unstabilized chlorine tablets?

    Stabilized chlorine tablets last longer, dissolve slowly, and can withstand exposure to sunlight. They are suitable for outdoor pools and can be used for both above-ground and in-ground pools. Unstabilized chlorine tablets dissolve faster and are ideal for small pools, hot tubs, and indoor pools that are covered.

  • How does the chemistry of chlorine tablets work?

    Chlorine tablets typically contain trichloro-s-triazinetrione as the main ingredient, along with other chemicals to increase their effectiveness and lifespan. The mixture of chemicals helps fight algae and slows down the dissolution rate of the tablets. Different tablets have varying chlorine release rates and effectiveness, so it is important to choose the right tablets based on your pool’s needs.

  • Conclusion

    Using the best chlorine tablets in the right quantity and at the right time will mean you can keep your swimming pool water crystal clear without spending too much money. When it comes to choosing the best chlorine tablets for your swimming pool, three standout options emerge.

    In The Swim 3 Inch Pool Chlorine Tablets offer long-lasting chlorination with their powerful and stabilized formula, ensuring the right dosage for optimal water treatment. For quick pool cleaning, In The Swim Chlorine Pool Shock is an effective and affordable choice, rapidly eliminating bacteria and algae.

    Finally, Clorox Pool and Spa Active99 provide continuous pool use with their UV-resistant, individually wrapped tablets that effectively kill algae and bacteria. Consider your specific needs and preferences to select the ideal chlorine tablets for maintaining a clean and safe swimming pool environment.

    We hope that the guide will help you decide on which one is better suited for your swimming pool. Carefully read the reviews of each product and tally them against your pool’s requirements before you make the decision to buy any of these.

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