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Chlorine is commonly added to swimming pools and hot tubs to kill algae spores, bacteria, and small insects. Despite its lethality to microorganisms and insects, much like pool shock, the water remains safe for humans as long as the level of chlorine remains between 1 and 3 parts per million (ppm) and the pH balance of the pool water consistently stays between 7.2 and 7.8.
While liquid chlorine is an option, pool chlorine tablets offer a convenient alternative because they’re premeasured and dissolve over time without significantly increasing chlorine levels in any one section of the pool. These tablets contain high amounts of chlorine, helping to control and kill bacteria, algae, insects, and other microorganisms. Liquid chlorine can’t make the same claim; moreover, swimmers must exit the pool for at least 30 minutes after a liquid chlorine treatment. Our favorite is the Clorox Pool&Spa Active99 3-Inch Chlorinating Tablets thanks to their effectiveness and ease of use.
Learn about the important factors to consider when choosing the best chlorine tablets for your pool and review some of the top-rated selected and/or tested products on the market. This guide includes tips to make an informed decision about which option should work best for maintaining the level of chlorine in swimming pools and hot tubs.
- BEST OVERALL: Clorox Pool&Spa Active99 3-Inch Chlorinating Tablets
↓ Jump to Review - RUNNER-UP: Rx Clear 1-Inch Stabilized Chlorine Tablets
↓ Jump to Review - BEST BANG FOR THE BUCK: In The Swim 3-Inch Stabilized Chlorine Tablets
↓ Jump to Review - BEST WITH ALGICIDE: Clorox Pool&Spa XtraBlue Chlorinating Tablets
↓ Jump to Review - BEST TABLET DISPENSER: AquaAce Pool Chlorine Floating Dispenser
↓ Jump to Review - BEST FOR SALTWATER POOLS: HTH 42040 Super 3-Inch Chlorinating Tablets
↓ Jump to Review - BEST LONG-LASTING: HTH 42055 Pool Care 3-Inch Chlorine Tablet
↓ Jump to Review
How We Chose the Best Chlorine Tablets
We looked at the top brands on the market to curate our list of recommendations for the best chlorine tablets. When gathering our top picks, we made sure to include several options for both 1-inch and 3-inch tablets to suit a variety of swimming pool setups. Our research and hands-on testing showed us that trichlor is the most common type of pool chlorine tablets, so our list includes several of these options from various brands.
Lastly, we looked at several quantity options to suit shoppers looking to buy in bulk as well as smaller options suitable for small swimming pools or hot tubs while keeping to a tighter budget.
Our Top Picks
A pool vacuum and filtration system can’t do all the work to keep pool water clean and clear. The top choices in this list represent some of the best chlorine tablets on the market that balance the chemical composition of pool water, which we selected or tested based on the abovementioned considerations in addition to overall quality.
Best Overall
Clorox Pool&Spa Active99 3-Inch Chlorinating Tablets
Product Specs
- Type: Trichlor
- Quantity: 35 pounds
- Tablet size: 3 inches
What We Like
- The 35-pound package lasts a long time; could cover a whole season
- Easy to use; simply drop the required number of tablets in a feeder or floater
- Reputable brand for cleaning and sanitization
- Provides sunlight protection to prevent algae and scale growth
What We Don’t Like
- Can leave behind a strong chlorine odor in the water or on the skin
This 35-pound bucket of individually wrapped Clorox chlorine tablets is a good option for pools that are used regularly throughout the swimming season. Each 3-inch tablet can treat up to 5,000 gallons of water, on average, though weekly pool chemistry testing is still recommended to maintain appropriate chlorine levels. These tablets dissolve slowly via a skimmer or a floating dispenser.
These trichlor pool chlorine tablets include a stabilizer that helps reduce chlorine breakdown caused by UV radiation, keeping the pool water balanced and safe over a long period in contrast to unstabilized chlorine products. These can degrade under the sun’s glare, releasing harmful chloramines into the water, which can cause eye redness and skin irritation.
Get the Clorox Active99 chlorine tablets at Amazon or Lowe’s.
Runner-up
Rx Clear 1-Inch Stabilized Chlorine Tablets
Product Specs
- Type: Trichlor
- Quantity: 8; 15; 25; 35; 50; 100; and 1,200 pounds
- Tablet size: 1 inch
What We Like
- Available in multiple quantities depending on the size of the pool
- Prevents burn-off from harmful UV rays while killing bacteria, algae, and disinfectant
- Suitable for use with any automatic dispensers currently in place
What We Don’t Like
- Some users have reported that the tablets arrived broken
- Requires 7 tablets per 2,500 gallons of water; users with large pools can go through a lot of tablets quickly
Use this bucket of 1-inch trichlor chlorine tablets from Rx Clear to treat bacteria and algae blooms in pool water. The stabilized formula resists degradation under direct sunlight, reducing the production of chloramines in the water. These chlorine tablets are slow to dissolve, making them a good option for distribution through the pool skimmer or an automatic tablet dispenser.
The manufacturer doesn’t indicate if the tablets are individually wrapped. When they’re stored together with no wrapping, it can cause them to chip, crack, or break during transit, leaving powder, granules, and small pieces of tablet at the bottom of the bucket. However, users can still measure and use the broken chlorine tablets at a ratio of 1 pound per 10,000 gallons of pool water.
Get the Rx Clear chlorine tablets at Amazon.
Best Bang For The Buck
In The Swim 3-Inch Stabilized Chlorine Tablets
Product Specs
- Type: Trichlor
- Quantity: 50 pounds
- Tablet size: 3 inches
What We Like
- 1 tablet can clear over 5,000 gallons of pool water; suitable for those with large pools
- Individually wrapped tablets ensure precise quantity is added to a feeder or floater
- Durable container provides safe storage; prevents the tablets from breaking before use
- The affordable bulk quantity provides enough tablets for a whole season of pool use
What We Don’t Like
- High up-front cost may not be ideal for some users on a budget
- Not to be used with a skimmer; floater or feeder only
Properly maintaining pool water doesn’t have to deplete your bank account. Keep the water clean and clear with this 50-pound bucket from In The Swim that contains approximately 80 3-inch tablets. These pool chlorine tablets are individually wrapped in easy-to-open plastic packaging, which helps prevent dust, chips, and small broken pieces from falling to the bottom of the bucket.
The trichlor chlorine tablets are made with a stabilizer, so the chlorine in the pool is resistant to UV radiation, reducing the production of harmful chloramines. Each tablet treats about 5,000 gallons of pool water and can be used in floating chlorine dispensers and automatic chlorine dispensers, but not in skimmer baskets.
Get the In the Swim chlorine tablets at Amazon or Leslie’s Pools.
Best With Algicide
Clorox Pool&Spa XtraBlue Chlorinating Tablets
Product Specs
- Type: Trichlor
- Quantity: 5, 12, 16.5, 25, and 35 pounds
- Tablet size: 3 inches
What We Like
- Formula is made to prevent scale, corrosion, and stains while killing green, mustard, and black pool algae
- Made with an integrated chlorine stabilizer for long-lasting sun protection
- Comes in multiple quantities to accommodate different size pools
What We Don’t Like
- Some of the tablets may chip or break before use
- Slightly pricey compared to other options on the market
Algae is one of the biggest causes of unsightly green pool water. To avoid any unwanted bacteria and algae growth, we recommend the Clorox Pool&Spa XtraBlue chlorinating tablets. These 3-inch tablets are made with a trichlor formula that prevents corrosion, scale, and stains while killing green, mustard, and black poolalgae growth. Plus, it offers long-lasting sun protection with an integrated chlorine stabilizer.
Simply put these pool chlorine tablets in a feeder, floater, or skimmer once a week for best results. It’s available in multiple other quantities including 5, 12, 16.5, and 25 pounds.
What our tester says: Stephanie Cronk, executive editor of Product Reviews for BobVila.com, notes that “we love using the Clorox chlorine tablets in our pool, when available locally. They tend to sell out pretty quickly. We notice that the Clorox tablets make our water softer and prevent our skin and hair from drying out. These tablets also keep the pool clean and clear without a strong odor.”
Get the Clorox XtraBlue chlorine tablets at Amazon or Lowe’s.
Best Tablet Dispenser
AquaAce Pool Chlorine Floating Dispenser
Product Specs
- Type: Tablet dispenser
- Quantity: Holds up to 5 tablets
- Tablet size: Holds tablets up to 3 inches
What We Like
- Easy to set up and maintain; simply add the tablets to the floater and place in the pool
- Adjustable flow control keeps the amount of chlorine in check
- Durable plastic design can withstand years of use
- Holds over 5 chlorine tablets; suitable for small to large pool varieties
What We Don’t Like
- Tablets are not included with purchase; need to be purchased separately
When selecting a chlorine dispenser for the pool, consider the convenience of a floating dispenser. This AquaAce pool chlorine floater dispenser is easy to load with chlorine and can be used in any pool. Made of durable plastic, it features 15 flow vents that are fully submerged, allowing water to dissolve the tablets into liquid chlorine slowly over several hours.
This chlorine tablet dispenser is wide enough to hold 3-inch tablets and has enough space to load up to five chlorine tablets at a time. Users can adjust the flow of water through the dispenser by twisting the base to open or close the flow vents for manual control of the chlorine release. This prevents its chlorine concentration in the water from growing too high.
Get the AquaAce chlorine tablet dispenser at Amazon.
Best For Saltwater Pools
HTH 42040 Super 3-Inch Chlorinating Tablets
Product Specs
- Type: Trichlor
- Quantity: 25 pounds
- Tablet size: 3 inches
What We Like
- Easy to use; simply drop the required amount of tablets in a feeder, floater, or skimmer
- 1 tablet prevents insects, algae growth and spores, and bacteria in up to 10,000 gallons of water
- Suitable for use in both chlorinated water and saltwater pools
What We Don’t Like
- Slightly more expensive than some comparable options on the market
It’s important to find a product that’s suitable for your specific pool; otherwise, the chlorine content may be too harsh for soft vinyl liners and saltwater filtration systems. However, the 3-inch chlorine tablets in this 25-pound bucket from HTH are created with a trichlor chlorine formula that can be used safely in saltwater systems, according to the manufacturer.
Each tablet effectively treats about 10,000 gallons of water. Once the tablet has dissolved in the pool water, it releases the chlorine to kill bacteria, insects, and algae spores for up to 1 week.
Get the HTH 42040 chlorine tablets at Amazon.
Best Long-lasting
HTH 42055 Pool Care 3-Inch Chlorine Tablet
Product Specs
- Type: Trichlor
- Quantity: 25 pounds
- Tablet size: 3 inches
What We Like
- The slow-dissolving formula is made to deliver clean water for over a week; comes with integrated sun protection
- 3 tablets are capable of cleaning pools of over 10,000 gallons (chlorinated water or saltwater)
- Made with a sanitizer and algicide for crystal-clear pool water
What We Don’t Like
- Some users have reported that the tablets are not as durable as comparable options
Those who prefer the set-and-forget method can trust the HTH 42055 Pool Care 3-inch chlorine tablets. These chlorine tabs are made to sanitize and clarify the pool water with the help of an integrated algicide. They are also slow-dissolving and offer sun protection that lasts for over a week in pools of up to 10,000 gallons. Simply drop a few chlorine tabs into a floater, feeder, or skimmer basket, even in pools with salt water or vinyl lining.
Get the HTH 42055 chlorine tablets at Amazon, Lowe’s, Ace Hardware, or The Home Depot.
Jump to Our Top Picks
What to Consider When Choosing Chlorine Tablets
When selecting chlorine tablets, note several factors, including the type, size, and dissolving speed of the tablet, as well as the appropriate amount of pool chlorine for the size of the pool along with a few key safety tips. Keep reading to learn more about choosing the best chlorine tabs to balance the chemical composition of pool water.
Type
Users can select from several different types of chlorine treatments for a swimming pool or spa, including sodium hypochlorite, lithium hypochlorite, calcium hypochlorite, dichlor, and trichlor. Trichlor is the most commonly used treatment.
- Sodium hypochlorite is a good option if the pool’s water filtration system struggles with high calcium hardness. However, it contains only about 10 to 12 percent chlorine, so it isn’t the most effective at killing algae or bacteria. Moreover, sodium hypochlorite chlorine treatments are nonstabilized, which means they are vulnerable to degradation in sunlight and can produce harmful chloramines that cause red, itchy eyes and skin irritation.
- Lithium hypochlorite has a higher range of 28 to 35 percent chlorine, which allows it to maintain the chemical balance of the pool water more effectively. However, lithium hypochlorite is not stabilized and is vulnerable to UV radiation.
- Calcium hypochlorite is another nonstabilized pool treatment. While more effective than both sodium hypochlorite and lithium hypochlorite and with a chlorine percentage of about 65, calcium hypochlorite is still vulnerable to UV radiation and chloramine production.
- Dichlor chlorine treatment is combined with cyanuric acid to create a stabilized chlorine treatment that’s resistant to UV radiation and slows the breakdown of chlorine molecules and the release of chloramines into the pool. Dichlor products are typically granular instead of solid tablets, and their chlorine content ranges from 56 to 62 percent.
- Trichlor is the most common chlorine treatment for swimming pools. Containing up to 90 percent chlorine, solid trichlor chlorine tablets are another form of stabilized chlorine. Once a tablet dissolves in the pool water, the treatment resists degradation under direct sunlight and UV light, slowing the production of chloramines.
Size
Chlorine tablets usually come in two sizes: 1-inch small tablets and larger 3-inch tablets.
- 1-inch chlorine tablets are a good option for small pools, hot tubs, and spas, because they release a small amount of chlorine at a quick-dissolving speed, rapidly increasing the chlorine level to the correct concentration. However, these tablets are ineffective in larger pools that hold more than 5,000 gallons of water.
- 3-inch chlorine tablets are ideal for large pools because one tablet can treat about 5,000 gallons of water, on average. Pools with more than 5,000 gallons of water can use more than one chlorine tablet, though the dissolving time is much slower for 3-inch tablets.
Both sizes can be used in skimmers, floating chlorine dispensers, and automatic chlorine dispensers, so choose the right type based on the size of the pool.
Dissolving Speed
The dissolving speed of a chlorine tablet can be difficult to determine based on product information alone. Factors like application method, water temperature, water pressure, and the size of the tablet can impact the amount of time the tablet takes to break down.
The 3-inch chlorine tablets break down at a slower rate than 1-inch chlorine tablets, while tablets placed in the skimmer rely on a continuous water flow through the filtration system to break them down. Floating dispensers gradually dissolve tablets, but the dissolving speed is unreliable because they simply bump and bob throughout a pool with inconsistent water flow. Automatic dispensers typically have a set rate that will dissolve a chlorine tablet within 2 to 5 hours depending on the size, though users can adjust these devices to increase or decrease the dissolving speed.
Amount
The amount of chlorine required differs for pools, hot tubs, and spas. First, test the water with a pool test kit to determine the pH and chlorine level in the water. Ideally, the pH level should fall between 7.2 and 7.8, while the chlorine level should range between 1 and 3 ppm for the water to be considered safe.
On average, one 3-inch chlorine tablet can treat between 5,000 and 10,000 gallons of water, depending on the manufacturer. However, a single 1-inch chlorine tablet can treat only about 350 gallons of water. If the tablets are chipped or broken, users may need to estimate the treatment based on weight by using 1 pound of chlorine tablets per 10,000 gallons of water.
Safety
Adding chlorine tablets to a pool is relatively easy with a skimmer, an automatic tablet dispenser, or a floating-tablet-dispenser system. Most chlorine tablets are packaged in a large bucket or container, but many manufacturers also produce individually wrapped tablets to help prevent them from breaking, cracking, and crumbling in transit.
Even if individually wrapped tablets break, the dosage remains consistent, instead of having to measure out the powder, crumbs, and chips from the bottom of the container. Chlorine tablets can emit a strong odor that’s dangerous in enclosed spaces, so always close and store the container properly. Moreover, use gloves to avoid directly touching the tablets: The high chlorine level can irritate the skin.
FAQs
Along with pool pumps and filters, chlorine tablets are necessary to maintain most swimming pools. However, not everyone knows how they work or how to use them. For answers to these concerns and more, take a look at some of the most frequently asked questions about chlorine tablets.
Experts don’t recommend using chlorine tablets for household cleaning because they contain a high amount of chlorine, which can damage toilets, sinks, and appliances. The chlorine can also cause strong odors in enclosed spaces that are harmful if inhaled in large amounts.
You can add chlorine tablets to the pool in several ways. Use a floating chlorine dispenser that holds the tablet in a basket until it’s fully dissolved. Place the tablet in a pool skimmer where the water will be pulled over it, quickly and efficiently adding chlorine to the pool water. Finally, load an automatic chlorine dispenser with a tablet and set it for a specific chlorine level. The dispenser gradually releases the chlorine into the pool.
The specific number of chlorine tablets to add per week depends on the size of the pool and the size of the tablets. However, you can use a pool test kit to help maintain a 1 to 3 ppm chlorine concentration in the pool water. You’ll also need to test for the appropriate pH level, keeping it between 7.2 and 7.8 to ensure safe swimming water.
