Chlorine Tablets vs Granules

When the swimming pool’s usage is on a different day today, the temperature conditions can be extreme stressing disinfection through the summer season. What is the best way to add Chlorine to your swimming pool chlorine tablets or granules?

Chlorine Granules

Granular contains more inert Ingredients
You can adjust the amount according to chl. residual
Bump the chl. residual to create a shock effect
Save the cost of Shock Chlorine


Easy use
Won’t interfere with swimmers
Will last longer
Won’t damage the liner or pool paint
Need to Shock more

For convenience, Chlorine Tablets are easy to use and work efficiently, to keep chlorine level in pool water but can’t give you the kind of controls that Granular Chlorine can give over the maintenance of you’re swimming pool. Here are some methods using Granular Chlorine that can keep your pool smooth sailing during the dog days of summer.


Welcome to the splashy showdown of the century, a chlorine clash fit for the ages! Diving into the crystal-clear world of pool maintenance, we size up two titans of the tank: the steadfast Chlorine Tablets and the gritty gladiators known as Chlorine Granules. Which one will float to the top as the champion of chlorination? Prepare to immerse yourself in a comprehensive comparison that promises to demystify these purifying powerhouses for your pristine pool paradise.



Chlorine Tablets vs Granules


Chlorine granules or granular chlorine is made up of Calcium hypochlorite, a dry crystallized compound of chlorine, that is commercially available in dry mixtures containing up to 80% calcium hypochlorite, though 65–75% is more common and lower concentration formulations are also available.

High strength Calcium Hypochlorite has been widely used as a disinfecting agent in swimming pools and municipal water treatment since 1928.

It is a convenient source of available chlorine, one of the most widely used chemicals for disinfecting swimming pool water and hot tubs. A concentrated source of chlorine in solid form Provides a residual level of free available chlorine (FAC) in the pool and spa water to kill disease-causing organisms.

Granules of chlorine act as a sanitizer, algaecide, and/or shock product depending on the amount and application method. It destroys bacteria and contaminants in pool and spa water such as those found in sweat, urine, and windblown debris.

It does not contain a stabilizer (cyanuric acid), though it can be stabilized for extended disinfecting power when (cyanuric acid) is added to pool water usually separate from the chlorine granules.

Available in slow-dissolving tablet forms or more rapidly dissolving granular forms and requires the use of some specialized storing and handling. Calcium Hypochlorite can be used as a sanitizer every day. As long as the PH is between the range of 7.2 and 7.8. When used properly, hypochlorous acid will be the direct result which will kill algae, bacteria, and other microorganisms to control the sanitization of the swimming pool.

Besides being used as a sanitizer it can be used as an algicide and will oxidize contaminants and chloramines. If the free chlorine levels are where they should be, the water test will be at 1.0-4.0 ppm Hypochlorite will properly sanitize you’re pool and will kill off many populations of microorganisms in any conditions as they try to grow in your pool.

With Calcium, too little is not good but too much can cause some problems like cloudy water or scale formations in the water.  When using  Sodium Hypochlorite,  there may be a rise in hardness and alkalinity that causes Calcium Carbonate. You will then need the water to be balanced. The easiest way to deal with this is to empty some of the pool water. That’s it!

Understanding Chlorine Use in Pool Sanitation


When diving into the sparkling world of pool upkeep, pool chlorine stands as the guardian of hygiene, vigorously defending against unwelcome microscopic invaders. Chlorine, in its various forms, ensures your pool water remains a bastion of cleanliness, from the smallest backyard pool to the grandest hot tub spa. As a pool owner, it’s vital to fathom the depths of this essential element’s use, lest you find yourself adrift in muddied waters. Both chlorine tablets and chlorine granules often feature in these sanitizing escapades, their use tailored by the pool’s conditions and the caretaker’s preferences.

Many choices abound within the realm of pool chemicals, but understanding the nuances between chlorine tablets and chlorine granules becomes paramount for maintaining optimal levels of free chlorine. These tablets, beloved by many for their ease of use, slowly dissolve, releasing chlorine over many hours, thus offering a steady hand in preventing the growth of algae and bacteria. They’re an excellent choice for pool owners who appreciate convenience; just pop them in your pool’s skimmer, floater, or automatic feeder, and let the tablets go to work. Conversely, chlorine granules provide a more manual but no less effective means of purification, dissolving swiftly to bolster free chlorine levels posthaste.

The grain of truth in deciding between these stalwarts of sanitation often boils down to conditions and usage habits. Granules are superb for shocking a pool, rapidly ratcheting up chlorine levels to wrest control from any biological interlopers. Tablets can claim dominance in ease and consistency, presenting a fuss-free option for ongoing maintenance especially in hot tub spas. Additionally, the amount of chlorine required in pool water varies with usage, weather conditions, and size, dictating that the use of either product should be informed by regular water testing.

Ensuring that the range of free chlorine level remains within safe and effective parameters is an art in itself. By leveraging chlorine tablets or granules, you can manipulate your pool’s chemistry to perfection, ensuring that it’s not just clean but a sanctuary of health. The type of product also depends on your pumps and how they distribute the pool chemicals. Tablets tend to have a longer life span, reducing the need for frequent top-ups, whereas granules can be used to quickly correct levels when they dip.

Now, let’s consider those pool or hot tub enthusiasts living in conditions where temperatures soar—the relentless sun can diminish chlorine levels at an alarming rate. Chlorine tablets are particularly apt for these scenarios, offering a steady delivery system that withstands the solar onslaught. For a spa, it’s also crucial to maintain chlorine levels given the high temperatures, as it affects how much chlorine the water can hold before it becomes ineffective.

Whether your aquatic paradise is a hot tub or a grand pool, the amount of free chlorine in the water must align with its use. A family pool that sees many playful splashes will undoubtedly require more frequent chemical attention than a lone swimmer’s spa. The frequency of use and the conditions of the environment play pivotal roles in the free chlorine level stakes.


How Do Chlorine Tablets Work in Maintaining Your Pool’s Cleanliness


TCCA 90% Chlorine Tablet for Swimming Pool Cleaning, 1Kg, 5-Tablets per Tube, 3" diameter | Lazada PH In swimming pools, chlorine tablets loaded in a floating dispenser are used not only to kill bacteria in the water but also to prevent the growth of algae and to maintain the proper pH level. The pH level is a rating on a scale that indicates how acidic or caustic a substance is. A safe pH level for a swimming pool is between 7.2 and 7.6. The same as Granular Chlorine

Calcium Hypochlorite can also work well in spas and will sanitize at levels of 2.0-5.0 ppm. When Calcium Hypochlorite is used to disinfect pool water then .08 ppm of calcium is added every time 1.0 ppm of Free Chorine is added to the pool.

Swimming pools usually need a measurement of 150 ppm-1000 ppm of calcium Hardness in the chemistry of the water. So testing needs to be done now and again to make sure levels aren’t climbing.

Chlorine tablets are solid pellets of a chemical compound containing chlorine that is used to disinfect and purify drinking water and water used in swimming pools. Chlorine has long been used to kill bacteria and microbes in water to make it safe. In its gaseous form, however, it is poisonous. Chlorine tablets in a floating dispenser became one of the most common and easiest methods for people to get the desired results safely.

Tablets are easy to apply to your swimming pool by just adding tablets to floater dispensers to the water. But your pool will need to be shocked most likely weekly or even more depending on the amount of use. You have no control over the residual or when or how the sanitizer is added.

Less control of a pool means more money. Adding Chemicals to your pool should be done on some type of schedule but then there are times because of usage or other conditions that make it impossible.

How to Add Chlorine Granules


Whenever you shock your pool or add chemicals empty the pool of rafts, tubes, covers, and floats and any organic material like leaves that are on the bottom of the pool or floating on top of the water that will absorb pool chlorine and pool chemicals.

You don’t want to waste any of it.

  • Always add chlorine at night for the best disinfection rate and the absence of sunlight that burns Chlorine off. Pool Water Chemical Levels Chart - In The Swim Pool Blog
  • Adjust the pH level of the pool if you need to before adding chlorine
  •  If you need to adjust the pH You may also need to wait because PH will take a while for the water’s chemistry to change. It’s a slow process. You don’t want to do it too fast or you’ll be ping-ponging from pH Low to pH High and back. In order for the complete bacteria to kill with any kind of chlorine your pH has to be right!
  • Also, keep the pool filter running.
  •  Use a 5-gallon bucket you can buy at Home Depot and mix a couple of scoops of approximately 2 libs of Calcium Hypochlorite chlorine granules with a 2/3 bucket of pool water.

It’s not an exact science. Don’t kill it, just dilute the Granular Chlorine you need according to the Chart and walk the perimeter of the pool slowly pouring the contents of the bucket a foot or so off the wall so it will have some contact.

This is a good way to deliver chlorine fast and lethal. If you have a vinyl bottom on the pool, it will keep the Granules from laying on the bottom and damaging it.

The new granules of chlorine as Calcium Hypochlorite are stronger than they used to be with up to 70% Available Chlorine and 73% Active Ingredient which is close to what a good quality Pool Shock is. It has fast-acting dissolving crystals so you won’t have to mix and dissolve it, especially in a concrete or cement pool.

You can play with numbers and use the chart as a ballpark reference guide. Apply it all at one time by broadcasting the Granular around the parameter walls of the pool. If you dilute it then cover as much of the surface as possible. But try and add it fast and all together in one shot.

If your pool was 30,000 gallons and you were using Calcium Hypochlorite with 67% Active Ingredient to “Bump” the pool to 5ppm you would have to add approximately 2 lbs of Granular Chlorine to super-chlorinate the pool water. Add it Fast. So the Pool water gets the Chlorine all together in one shot. It really is effective that way.

In a concrete or cement pool, you wouldn’t have to dilute and mix the chlorine granules that are fast dissolving. You can walk around the pool and broadcast the granules as you move around the perimeter walls. There is stronger “Hypo” granular chlorine available that is up to 70% available chlorine. If you experiment you can add or reduce the amount you need to “Bump” to double the Residual.

Use reliable test kits along with fresh reagents (check for expiration dates on the bottles) before Testing Pool Water.


What is the best Swimming Pool Return Jets Position?

At the Deepest End of the pool
turn the Return Jets (eyeballs) located on the pool walls angled down toward the bottom of the pool at a 45° angle

In the Shallow End of the pool
Turn return Jets clockwise to about 8 o’clock at a 45° angle so the return water to the pool is mixing in a circular motion. …………………………………………………………… Read more


Use “Bumping” to Increase Chlorine Levels and Control Bacteria

“Bumping” You’re Pool Or Super-Chlorinating

A bump to your chlorine level is just to boost its strength and get a handle on any growing algae or if you are expecting a large crowd to use the pool.  You can buy fewer chemicals using chlorine granules during a super-chlorination or a “Bump” than if you were to Shock the pool with other super-chlorinating pool products.

The goal is to double the normal residual that you normally have in your pool. Bacteria and Algae have a tendency to adjust to some chlorine residual by hiding out in cracks and crevices or underneath dead bacteria growth.  With some Brushing a few times a week along with “Bumping”  your residual will be enough to get a good kill and crystal-clean water.

You can save a lot of money by not shocking the pool with chlorine granules every week as the Pool Store wants you to do.  It’s a waste of money. It will pay off this summer. Be the Master of your Swimming Pool by controlling it with good testing and procedures.



Can You Put Chlorine Granules in the Pump Basket


No, it is not recommended to put chlorine granules directly into the pump basket. Chlorine granules are designed to be dissolved in water before they are added to the pool. Adding them directly to the pump basket can lead to poor distribution and may damage the pump or other equipment due to concentrated chlorine in one area. Instead, follow the manufacturer’s instructions on how to add chlorine granules to your pool. Typically, this involves pre-dissolving the granules in a bucket of water and then pouring the solution into the pool.

You should never add chlorine granules or powder, or chlorine tablets like dichlor, trichlor, or liquid chlorine to a pool pump basket. Chlorine is a strong and often acidic chemical that will the seals and plastic components in your pool pump as well as other pool equipment like pool filters.

Chlorine in any form should never be added to your pool’s pump basket as it will damage the pump and reduce the life of other pool components. Many pool owners probably are unaware of the dangers of doing this, but we’ll do our best to explain why this should be avoided.

The Pools Pump Basket contains rubber seals and gaskets that will damage plastic baskets and even the pool heater. When chlorine sits in a pool basket, it will turn acidic and when the pool turns on will shoot directly into the filter This wouldn’t be good for a sand filter or a cartridge filter.


How You Can Slow Pool Evaporation?

Slow Down Pool H2O Evaporation By:

Minimize the time H2O is exposed to sun-air & wind by turning off H2O features like waterfalls
Keep Pool heater set at Cooler Temperatures  
Use a Pool Cover-Foam, Bubble
Use Solar Rings
Leave floats in a pool during the day
Keep outlet jets angled down
Add tree & bush shade …………………………………………………………………………………………………………………………. Read more

Total vs Free vs Combined Chlorine

Free Chlorine

This is the chlorine that you test for in your swimming pool water. This type of chlorine is available to sanitize your pool. Your pool should have chlorine levels between 1 and 3 parts per million (ppm) in the water.

Combined Chlorine

This is chlorine that has been used up by the disinfection process of the water. While it’s still in the water, its ability to sanitize is reduced and not as desirable as free chlorine.

Total Chlorine

This type of chlorine is the sum of both free chlorine and combined chlorine. 

When you add a number of chlorine granules to your pool or tub chemicals to your hot tub, it reacts with the water to form hypochlorous acid and hypochlorite ions. This is a desirable form of free chlorine in pool water to the hot tub. You can’t get the same chlorine levels in your pool with chlorine tablets or a dispenser.

These compounds together form what we call free chlorine. Once this chlorine begins to react with the contaminants in the pool water, such as nitrogen and ammonia, it is called combined chlorine. This is chlorine with less disinfecting power for your pool or hot tub.

In this state, chlorine isn’t as strong at cleaning compared to free chlorine as it begins to be used up. You want to make sure your free chlorine levels stay in check. This ensures the job has been done. For example, if your free chlorine levels and total chlorine levels are the same, then there’s no combined chlorine in your water.

If your total chlorine level is higher than the free chlorine level, the difference between the two is the combined chlorine level. *To make sure your pool or spa is sanitized, your free chlorine should remain higher than your combined chlorine.

Total chlorine and free chlorine are terms often used in the context of water treatment, particularly in swimming pools. Here’s a brief explanation of each:

  1. Total Chlorine:
    • Definition: Total chlorine refers to the overall amount of chlorine present in the water. This includes both free chlorine and combined chlorine.
    • Components:
      • Free Chlorine: Chlorine that is available to sanitize and disinfect.
      • Combined Chlorine: Chlorine that has already reacted with contaminants in the water, losing its sanitizing ability.
  2. Free Chlorine:
    • Definition: Free chlorine is the amount of chlorine in the water that is available to disinfect and kill bacteria and other harmful microorganisms.
    • Importance: This is the chlorine that is actively working to keep the water clean and safe.

Testing and Maintenance:

  • Testing: Pool water is regularly tested for both total and free chlorine levels. This is often done using test kits or electronic testers.
  • Ideal Levels:
    • Free Chlorine: Typically, the free chlorine level should be maintained within a specific range recommended for safe and effective sanitation.
    • Total Chlorine: The total chlorine level should be monitored to ensure that it doesn’t exceed the recommended levels.


  • If total chlorine is higher than free chlorine: This indicates the presence of combined chlorine, which may lead to chlorine odor and eye irritation. Additional chlorine may need to be added to break down the combined chlorine.
  • If free chlorine is too low: It may indicate inadequate sanitation, and more chlorine may need to be added to bring it to the desired level.

Regular monitoring and adjustment of chlorine levels are essential for maintaining a safe and sanitary swimming pool or water system.


Do I need to Remove Phosphates from my Swimming Pool Water?

No, It is unlikely that you will be able to remove all phosphate entering your pool:

  • Keep pool chemically balanced
  • Properly sanitized
  • Occasionally add algaecide & fresh H2O
  • Daily skimming
  • Scrubbing pool walls & floors
  • Using a flocculant
  • Then vacuuming
  • This practice will keep phosphate levels at bay at no cost .…………………………………………………………………………. Read more


Subtracting Free chlorine from Total chlorine will give the level of Combined chlorine in the pool water. When combined chlorine (chloramines) are 0.3 ppm or greater, Then that is when you consider Shocking the pool. Knowing the difference between the Chlorine residuals and how one affects the other, can result in you gaining more information and keeping your pool under your thumb for constant control.

*Using granular (granules) chlorine instead of Chlorine Tablets allows the “Bumping” technique to be a little more hands-on with the control of your pool. Just a little more work, but in the end, it will save you money and give you another weapon for becoming “the Master of your Pool”.

Have a Great Summer!


JimGalloway Author/Editor



Q: What are the main differences between chlorine tablets and granules for pool maintenance?

A: Chlorine tablets are slow-dissolving and provide a continuous release of chlorine, while granules dissolve quickly and offer a rapid increase in chlorine levels.

Q: Which one is more convenient to use, tablets, or granules?

A: Chlorine tablets are often considered more convenient for long-term maintenance, as they can be placed in a floating dispenser or a chlorinator for slow, consistent release. Granules may be used for quick adjustments.

Q: Do chlorine tablets or granules affect pH levels differently?

A: Chlorine tablets tend to have a stabilizing effect on pH, while chlorine granules can lower pH levels. Regular monitoring and adjustment of pH are essential regardless of the chlorine form used.

Q: Are there any specific safety considerations for handling chlorine tablets or granules?

A: Both forms of chlorine should be handled with care. Follow safety guidelines on the product packaging, and avoid direct contact with skin or eyes. Store them in a cool, dry place away from other chemicals.

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