Chlorine is a common additive in swimming pools and hot tubs that kills algae spores, bacteria, and small insects. Despite the lethality to microorganisms and insects, the water remains safe for humans as long as the chlorine level remains between 1 and 3ppm (parts per million) and the pH balance of the pool water is consistently between 7.2 and 7.8. While liquid chlorine is an option, chlorine tablets offer a convenient alternative because they are premeasured and dissolve over time without significantly increasing chlorine levels in any one section of the pool. Liquid chlorine can’t make the same claim, not to mention that swimmers must exit the pool for at least 30 minutes after liquid chlorine treatment.
This guide will cover the important factors to consider when choosing the best chlorine tablets for your pool and review some of the top-rated products on the market. Read on for more tips to make an informed decision about which option would work best for maintaining the chlorine level in your pool.
- BEST OVERALL: Clorox Pool&Spa Active99 3″ Chlorinating Tablets
- RUNNER UP: Rx Clear 1-Inch Stabilized Chlorine Tablets
- BEST BANG FOR THE BUCK: In The Swim 3 Inch Stabilized Chlorine Tablets
- BEST FOR SMALL POOLS: Clorox Pool&Spa Small Pool 1″ Chlorinating Tablets
- BEST TABLET DISPENSER: AquaAce Pool Chlorine Floater Dispenser
- BEST FOR SALTWATER POOLS: HTH 42040 Super 3-inch Chlorinating Tablets
What to Consider When Choosing the Best Chlorine Tablets
Before selecting chlorine tablets for your pool, several factors are important to note, including the type, size, and dissolving speed of the tablet, as well as the appropriate amount of chlorine for the size of the pool and a few key safety tips. Keep reading to learn more about choosing the best chlorine tablets to balance the chemical composition of the pool water.
Users can select from several different types of chlorine treatments to use in a swimming pool or spa, including sodium hypochlorite, lithium hypochlorite, calcium hypochlorite, dichlor, and trichlor, the latter of which 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 only contains about 10 to 12 percent chlorine, so this treatment isn’t the most effective at killing algae or bacteria. Also, sodium hypochlorite chlorine treatments are non-stabilized, meaning they are vulnerable to degradation under the sun 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. This allows it to more effectively maintain the chemical balance of the pool water, but lithium hypochlorite is also non-stabilized and vulnerable to UV radiation.
- Calcium hypochlorite is another non-stabilized pool treatment. While more effective than both sodium hypochlorite and lithium hypochlorite with a chlorine percentage of about 65, calcium hypochlorite is still vulnerable to UV radiation and chloramine production.
- Dichlor is a chlorine treatment that is combined with cyanuric acid, creating a stabilized chlorine treatment that is resistant to UV radiation and slows the breakdown of chlorine molecules and the release of chloramines into the pool water. Dichlor products are typically granular instead of solid tablets, and they have a chlorine percentage ranging from 56 to 62.
- Trichlor is the most common chlorine treatment for swimming pools. It contains up to 90 percent chlorine and comes in a solid tablet form. Trichlor chlorine tablets are also a form of stabilized chlorine. Once a tablet dissolves into the pool water, the treatment will resist degradation under direct sunlight and UV light, slowing the production of chloramines.
Chlorine tablets usually come in just two sizes: small tablets that measure 1 inch in diameter and larger tablets that measure 3 inches in diameter.
- 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 exceed 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 dispensers, and automatic chlorine dispensers, so focus on choosing the right type based on the size of the pool.
The dissolving speed of a chlorine tablet can be difficult to determine based on product information alone because factors like application method, water temperature, water pressure, and the size of the tablet can impact the amount of time it takes to break down.
The 3-inch chlorine tablets break down at a slower rate than the 1-inch chlorine tablets, while tablets placed in the skimmer are reliant on 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 the 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.
The amount of required chlorine isn’t uniform for every pool, hot tub, or spa. It’s necessary to 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 3ppm (parts per million) for the water to be considered safe.
On average, one 3-inch chlorine tablet will treat between 5,000 and 10,000 gallons of water, depending on the manufacturer. However, a single 1-inch chlorine tablet can only treat about 350 gallons of water. If the tablets are chipped or broken, users may need to estimate the treatment based on weight with 1 pound of chlorine tablets per 10,000 gallons of water.
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 together in a large bucket or container, but many manufacturers also individually wrap the tablets to help prevent them from breaking, cracking, and crumbling in transit.
Even if individually wrapped tablets do 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 it’s important to close and store the container properly. Also, use gloves to avoid directly touching the tablets because the high chlorine level can cause skin irritation.
Our Top Picks
The pool vacuum and filtration system can’t do all the work to keep pool water clean and clear. These top picks represent some of the best chlorine tablets on the market, selected based on the abovementioned considerations, in addition to overall quality, to balance the chemical composition of pool water.
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 will dissolve slowly via a skimmer or a floating dispenser.
These trichlor 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 of time. This is in contrast to unstabilized products that can degrade under the sun’s glare, releasing harmful chloramines into the water that cause eye redness and skin irritation.
This 8-pound bucket of 1-inch trichlor chlorine tablets from Rx Clear is an effective method of treating 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 also slow to dissolve, making them a good option for distribution through the pool skimmer or an automatic tablet dispenser.
There is no indication from the manufacturer that the tablets are individually wrapped. This can cause them to chip, crack, or break during transit, leaving powder, granules, and small pieces of chlorine tablet at the bottom of the bucket. However, users can still measure the broken chlorine tablets at a ratio of 1 pound per 10,000 gallons of pool water.
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. The chlorine tablets are individually wrapped with easy-to-open plastic packaging that 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 dispensers, automatic chlorine dispensers, and skimmer baskets.
It can be irritating to store a large bucket of chlorine tablets for months when the pool or spa is only large enough to use one or two tablets per week. Instead of choosing a bulk product, consider this 1.5-pound container of Clorox chlorine tablets. The tablets are just 1 inch in diameter, so users can add a small amount of chlorine to adjust the water chemistry to the appropriate pH and chlorine balance.
This package of trichlor chlorine tablets can treat pools, spas, and hot tubs that have up to 5,000 gallons of water. Due to the stabilizer in these tablets, the chlorine released into the pool water is resistant to UV radiation, slowing the production of chloramines. However, the tablets are not individually wrapped, so there may be some chipping and breaking.
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. It is made of strong, durable plastic and features 15 flow vents that are fully submerged, allowing water to slowly dissolve the tablets 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. This allows manual control of the chlorine release to prevent its concentration in the water from growing too high.
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, this 25-pound bucket of 3-inch chlorine tablets from HTH is made 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 one week.
FAQs About Chlorine Tablets
Chlorine tablets are a necessary addition to maintain most swimming pools, along with pool pumps and filters. 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.
Q. What do chlorine tablets do?
Chlorine tablets contain high amounts of chlorine that are released into the pool water to control and kill bacteria, algae, insects, and other microorganisms.
Q. Can chlorine tablets be used for household cleaning?
It’s not advised to use chlorine tablets for household cleaning because they contain a high amount of chlorine that can damage toilets, sinks, and appliances. The chlorine can also cause strong odors in enclosed spaces that are harmful if inhaled in large doses.
Q. How do I add chlorine tablets to my pool?
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 is fully dissolved. Place the tablet in the 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 to the pool with little effort.
Q. How often should I add chlorine tablets to my pool?
The specific number of chlorine tablets you should 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 3ppm (parts per million) concentration of chlorine in the pool water. You’ll also need to test for the appropriate pH level, keeping it between 7.2 to 7.8 to ensure the water is safe for swimming.