How many 3 inch chlorine tablets should I put in my pool

How many 3 inch chlorine tablets should I put in my pool

For a 15,000-gallon pool, start with 3 tablets and adjust weekly for optimal chlorine levels.

Determining How Many Tablets Your Pool Needs

How to calculate the pool size

In order to determine how many tablets of 3-inch chlorine you should use in your pool, you should at first calculate the pool size in gallons. For this purpose it is necessary to measure the length l width w , and avg depth D of your pool.

  1. Compute the volume of the pool: V = l w D .

  2. Multiply the result obtained in step 1 by 7.48 W gal.

For example, if a rectangular pool is 20 feet in length, 10 feet in width and the average depth is 5 feet, then the volume of a pool is: V = 20 10 5 = 1000 cubic feet; 1000 7.48 = 7480 gallons, the pool contains 7480 gallons of water.

How to determine the number of tablets

As the number of tablets depends on CYA and desired free chlorine level, it is recommended to have outdoor pools of 1-3 ppm free chlorine and CYA level of 301 – 502 . Considering that on average, a 3-inch chlorine tablet treats 5,000 gallons of water for approximately a week, it is also necessary to take in account such factors, as the temperature, direct sunlight, the usage of a pool. That is the higher the temperature, the increased amount of sunlight and pool visitors, the quicker 3-inch chlorine tablets dissolve.

For example, if a pool size is 10,000 gallons and free chlorine level should be 2 ppm, then for 40 ppm CYA level, the chlorine level should always equal 7.5% of the CYA level, that is, you should maintain such a chlorine level, CL = 40 0.075 = 3 ppm . As the one 3-inch chlorine tablet treats 5,000 gallons of water, considering that you have 10,000 gallons pool, you should use only 2 tablets. So having a 10,000 gallons pool you should every week put inside of the pool 2 tablets of 3-inch chlorine. However you should regularly test the water of your pool in order to adjust the number of tablets as the condition of your pool may change and take in account that the 3-inch chlorine tablets also have manufacturer’s instructions and safety requirements.

Pool Volume and Chlorine Tablet Ratio

Determining Pool Volume

It is important to calculate the correct ratio of chlorine tablets and water in your pool to keep it clean, and safe to swim. Firstly, you need to compute the volume of your pool. To do this, measure the length, width, and the middle depth of the pool in feet. Then, multiply the obtained figures to calculate the pool volume, in cubic feet. For example, if your pool is 20 feet long, 10 feet wide, and 5 feet deep the pool volume will be the following:

20 ft×10ft×5ft


cubic ft

20 ft×10 ft×5 ft=1000 cubic ft.

Then, convert the pool volume to gallons by multiplying the figure you have on 7.48 because 1 cubic foot equals about 7.48 gallons. For example, in your pool:

1000 cubic ft×7.48gallons/cubic ft



1000 cubic ft×7.48 gallons/cubic ft=7480 gallons.

Considering the above, your pool contains 7480 gallons of water.

Estimating Chlorine Tablet Utilization

Once you have calculated your pool volume, you can estimate how many chlorine shots you need to maintain the proper level of sanitation. It may vary depending on the size of your pool and the level of chlorine you want to support there. A typical tablet dissolves by 0.5-1 ounce per day, however, it depends on the temperature of the water, sunlight, and bather load. It is important to follow manufactures and safety guidance on how to measure the right dose correctly.

Determining Chlorine Tablet Utilization

Let us now calculate the number of tablets you need to support your pool of 10,000 gallons with a chlorine level of 2 ppm. If one tablet treats 5000 gallons and your pool contains 10,000 gallons of water you will need to add:

10 ,000gallons5,000gallons/tablet

2 tablets

5,000 gallons/tablet

10,000 gallons

=2 tablets.

Thus, to proper-use your pool, you will need to introduce 2 chlorine tablets first.

Environmental Monitoring

It is important to take a sample of water out of your pool regularly and check it with a test kit. If failing to maintain the level of chlorine concentration of 1-3 ppm in your pool wastes and minerals may appear, and it may become dangerous to swim. Moreover, the dose of chlorine tablets in your pool may vary form week to week.

Adjusting Tablet Quantity for Pool Size and Shape

Determining Pool Size

To determine the appropriate amount of 3-inch chlorine tablets to use, pool owners should consider the size and shape of the pool. The volume of the pool is calculated from its dimensions and is used to establish the correct number of tablets ensuring proper sanitation level and keeping the water safe. To calculate the volume of our pool, we need to know its length, width, and average depth. In the case of my swimming pool being 20-foot long, 10-foot wide and 5-foot average depth, I would calculate its volume as . Then, the pool volume has to be converted from cubic feet to gallons by multiplying it by 7.48 . I will end up with the volume of 7480 gallons for my swimming pool.

The number of three-inch tablets to use depends on the volume of water in the pool. The commonly recommended dosage is to use one 3-inch chlorine tablet per 5,000 gallons of water. In the case for my swimming pool being 7480 gallons, I would need for the initial treatment: . Since I cannot use a fraction of a tablet, I will round it up to two tablets.

Considerations for Pool Shape

Moreover, the shape of the pool may be taken in the consideration, affecting chlorine balance. For irregularly shaped pools, there may be areas in the pool where the water is not circulated as quickly as the rest of the pool, which may cause the chlorine to be distributed unevenly. In such cases, you may need to consider placing additional tablets or a floating dispenser to ensure that the pool water is properly chlorinated.

Therefore, if my pool was 15,000 gallons in volume and was also kidney-shaped, I would add three tablets to the pool since it is one tablet per five gallons and that is the volume of my pool. Regularly monitor your pools water chemistry using a test kit and adjust the number of tablets based upon the test results. Other considerations for adjusting the number of tablets to use are pool usage, weather conditions, and other factors affecting chlorine demand. Follow the manufacturer’s directions for using the tablets and also storage and handling information.

Best Practices for Chlorine Tablet Usage


Understanding Tablet Dissolution Rate

Before adding chlorine tablets to your pool, it’s important to know the rate at which a tablet dissolves. The 3-inch chlorine tablets generally dissolve at a rate of between 0.5 – 1 ounce per day per tablet. This rate can generally vary depending on several factors .

Calculating Pool Volume

Measuring your pool length, width and average depth of the water in feet then multiplying them will give the volume in cubic feet. Then multiple the volume of the pool in feet by 7.48 to get the total number of gallons in the pool since one cubic foot is equal to 7.48 gallons of water.

Calculating Tablet Quantity

Once you have found the gallon of the pool, you can determine the number of tablets required for your pool. As the general rule of thumb, for every 5,000 gallons of water, you will administer a 3-inch chlorine tablet to the water. It will require you to divide your total gallon by 5,000 to get the initial number of tablets to add to your pool.

Considering Pool Shape

When adding chlorine or any other pool chemical, you should consider the shape of your pool. In some pools, the slower moving ends contain chemical residues higher than indicated. You should add more tablets to the high residue area and also use a floater or a pool chemical dispenser. These will ensure that the chemicals distribute evenly. Where the tablets are empty, refill them and replace them with other tablets. Add the pool tablets through skimmer basket slot by partially plugging suction to your normal pool pump. You can also add tablets and another pool cleaning chemical.

Example Scenario

Suppose you have a rectangular pool with a volume of 20,000 gallons. Using the guideline of one tablet per 5,000 gallons, you would initially need:

\frac{20,000\ gallons}{5000\ gallons/tablet}=4\ tablets

So, you would add 4 tablets to the pool initially to achieve the desired chlorine level.

Monitoring and Adjustment

Regularly test your pool water to ensure chlorine levels remain within the recommended range (typically 1-3 ppm). Adjust the number of tablets based on test results, pool usage, weather conditions, and other factors affecting chlorine demand. Remember to follow manufacturer instructions for safe handling and storage of chlorine tablets.

Safety Precautions

Handle chlorine tablets with care and follow all safety precautions. Store them in a cool, dry place away from direct sunlight and moisture, and keep them out of reach of children and pets. Never mix different types of pool chemicals together, as this can cause dangerous reactions.