How Many Chlorine Tabs Per Week

Chlorine tablets can be a great and effective way to keep your water sanitized as long as you are using them properly. You should never rely solely on chlorine tablets for your chlorine reading in your pool water. Chlorine tablets should be more of your helping hand and below are some tips on how to use them properly.

The best rule of thumb for pool owners trying to estimate how many tablets to add is this: Add one tablet for every 5,000 gallons of water and always round up. For example, if your pool has 21,000 gallons of water, add five tablets per week. If it has 8,000 gallons, use two tablets.

How Often Should You Add Chlorine Tablets?

You typically will only need to add chlorine tablets one time per week. It is best that you pick a day that you will be able to perform some weekly maintenance and replenish chlorine tablets on a set schedule. This will become routine and make your pool care much easier.

If you have a 16,000 gallon pool, you would need to add 4 tablets one time per week. When you add the tablets each week it is also a good time to clean your skimmer and pump skimmer basket if you have one. Check to see if you need to clean your filters or backwash your pool and take care of all your pool care at once including testing your pool water.

Pro Tip! When it is your weekly schedule to add more chlorine tablets, look at how much chlorine is remaining. If the total amount of tablets equal 1 tablet by estimate you can count that tablet. Therefore if you add 4 tablets each week, you can add only 3 to bring the total back up to 4 making your chlorine last longer during the season. During the cool months when you water is cooler, this may occur from time to time. When the water gets warmer, chlorine will be dissolved at a much quicker rate.

What chlorine tablets are used for

Chlorine tablets are a safe, effective, and affordable way to sanitize your pool. They’re designed to gradually dissolve, releasing chlorine into your water as they get smaller and smaller.

They’re a popular choice amongst pool owners because of how easy they are to use. For the most part, it’s as simple as putting them in your water and leaving them to do their job. Of course, where you put them matters, hence this entire post.

Unlike granular or liquid chlorine, there’s no precise measuring involved with tablets. So it’s much faster. Just add the right amount of tablets for your pool size, and your good to go in just a few seconds.

BUT, as we mentioned earlier, there are right and wrong ways to use chlorine tablets, which we’ll be getting to in just a minute.

For now, let’s talk about the different types of chlorine tablets you’ll find at the pool store.

Chlorine tablets come in two main sizes: 1 inch and 3 inches

In most cases, you’re best off with 3-inch chlorine tablets, as one single tablet can treat up to 5,000 gallons of water.

On the other hand, 1-inch tablets contain far less chlorine (about half as much as 3-inch tablets), so they’re better suited for smaller indoor pools and spas.

Beyond size, there are also a few other differences between chlorine tablets when it comes to ingredients.

For instance, you’ll notice that certain tablets are labeled as either “stabilized” or “unstabilized”.

This refers to a specific ingredient, known as cyanuric acid (CYA), which helps to shield chlorine from burning up under the sun. Stabilized chlorine contains CYA, which helps it last much longer, and work properly even in sunlight.

Unstabilized chlorine doesn’t contain any CYA at all, which reduces it’s effectiveness and leaves it completely vulnerable to burning away in the sun within hours. Hence why unstabilized chlorine tablets are better suited for indoor pools, where the sun won’t be an issue.

If your pool is outdoors, choose stabilized chlorine tablets.

Certain chlorine tablet manufacturers also include extra chemicals, like algaecides and clarifiers in their products. These are helpful additions, but can always be added separately if needed later. So choose the tablets that fit your needs and budget.


1. Put chlorine tablets in the chlorinator or floater.

We always recommend using a chlorinator or floater for your chlorine tablets. A chlorinator will automatically disperse chorine into your pool at the rate you set it to. There is an adjustable setting on the unit that you should be able to change when needed. A floater has a similar concept. It is a plastic vessel that holds your tablets and floats around in the pool. These can also be adjusted to let more or less chlorine be released into your water.

2. Check chlorinator or floater weekly and refill as needed.

Adding chlorine tablets to your chlorinator or floater should be part of your weekly maintenance. Every week when adding your other maintenance chemicals, you should be checking your chlorinator or floater to see if any tablets need to be added. If your chlorinator or floater is empty, you should refill it with the appropriate amount of tablets.

3. Add one three-inch tablet for every 10,000 gallons of water in your pool.

You should never rely on your chlorine tablets for a chlorine reading. Chlorine tablets should only be a helping hand. Instead of filling your chlorinator or floater to the top with tablets, use one three-inch tablet for every 10,000 gallons of water in your pool. If you are shocking your water weekly, this amount of tablets should be perfect to maintain a good chlorine level.


How long does a 3 chlorine tablet last?

Properly stored chlorine tablets should last three to five years.

How long does one chlorine tablet last in a pool?

So how long it takes for a chlorine tablet to dissolve really varies for every pool. As a general rule, we see stabilized chlorine tablets (also called trichlor tablets) last anywhere from two to three days. Slow dissolve cal-hypo tabs may last four to five days.

How much chlorine do I need a month?

Calculate: 1 bag for each 10,000 gallons, per week or per month. Example: 2.5 bags per week for 20 weeks, or 50 lbs. Or 2.5 bags per month for 5 months, or 12.5 lbs. Recommendation: Get a 50 lb bucket of shock chlorine if you expect to shock weekly, or for 5 monthly shocks, you could buy the 12 Pack of pool shock.

How many chlorine tablets are in a floater?

You could fill it full, with 15 tablets, and put it on a setting of 1-2, or add only 2 tablets and put it on a setting of 8-9. Your test kit will help you determine the proper dial setting for your chlorinator.

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