How Much Chlorine To Add To a Pool?

woman using chlorine tablet for pool
Photo: Ladanifer/ Adobe Stock
woman using chlorine tablet for pool
Photo: Ladanifer/ Adobe Stock
Highlights
  • Your pool requires between one and four parts per million (ppm) of chlorine.

  • Use your pool’s gallon volume to calculate chlorine needs.

  • Choose from liquid, powder, or tablet forms of chlorine.

  • Accurate measurement ensures clean, safe water.

  • The average cost of chlorine for a pool is between $5 and $50 per week.

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Regularly adding swimming pool chlorine is crucial for maintaining a clean, clear, and safe swimming pool. However, knowing precisely how much chlorine to add can be challenging. Use this chlorine calculator to determine your pool's needs, but always double-check the product's label to avoid errors. 

How Much Chlorine Do You Need For Your Pool? 

Several costs make up the total price of pool maintenance. Chlorine is just one of them. However, its frequent use means that adding the right amount when necessary is essential for both safety and budgeting. 

Your pool needs to have between one and four ppm of chlorine measured against the water volume. To determine this, the first step is to calculate your pool's capacity, or volume, in gallons. 

Additionally, chlorine is available in several types. Knowing which type you'll use is another essential factor. 

The chart below assumes you're adding chlorine for regular maintenance to a three ppm level.

Size in gallonsLiquid chlorine (gallons)Chlorine powder (ounces)Chlorine tablets
5,0000.521
10,00013.52
15,0001.553
20,00026.54

How to Calculate How Much Chlorine Your Pool Needs

check chlorine water quality
Photo: Evgeniya Sheydt/ Adobe Stock

Regular testing will ensure you know precisely the chlorine level in your pool. When the level drops to around one ppm, it's time to add more. 

How to Measure Your Pool's Volume

The critical measurement when adding chlorine is the actual amount of water in the pool. To determine that, you'll need to know the cubic-foot volume of the pool multiplied by 7.5, which is the number of gallons in a cubic foot. 

To measure the volume of a rectangular pool with a constant depth, simply measure one short side, one long side, and the depth. Multiply the three values together and then multiply by 7.5 to determine the number of gallons. 

L x W x D x 7.5 = volume in gallons

How to Measure Pool Volume with Varying Depths

If your pool has a shallow end and a deep end with a continuously sloping bottom, multiply the length and width by the average depth, and then multiply the result by 7.5. Obtain the average depth by measuring the deepest and shallowest parts, adding the values, and then dividing the sum by two. 

How to Measure the Volume of Round Pools

To measure the volume of a circular pool, simply measure from one side of the circle to the other at its widest point. Divide the value by two, square it, and multiply that number by 3.14. Now, multiply the result by the depth and by 7.5 to calculate the total volume.

How to measure the volume of a round pool, with measuring the diameter and depth of the pool

How to Measure the Volume of Irregular Pools

To determine the volume of irregular pools, treat each section as its own pool. For example, if you have a sloping bottom in one part of the pool and a constant depth in another, determine the volume of each space and add the results together to find the total pool volume. 

Who to Hire to Maintain Your Pool

man checking ph level in pool
Photo: marcos/ Adobe Stock

Owning a pool requires continuous maintenance. While many homeowners gladly accept the challenge, pool maintenance pros do the job every day and are excellent at heading off chemical problems before they get out of hand. 

If you're confident in your pool maintenance skills, you can save some money by doing the chores on your own. However, even the job of adding chlorine can be tricky. Perfection depends on understanding how the weather, usage, and other variables affect the pool's chemicals. For that reason, hiring a local pool service is often the best route. 

Frequently Asked Questions

Chlorine performs several functions, depending on where and how you use it. In drinking water, chlorine in small amounts kills potentially harmful bacteria. It's also a common ingredient in detergents for its whitening properties. Most people associate the chemical with pool use, where it works to kill and control bacteria, germs, and viruses in the water. 

Chlorine has a shelf life of between six months and several years, depending on its type and formulation. Liquid chlorine can often lose its effectiveness in just a few weeks. Pool owners can find themselves with overstock that they need to get rid of. The best way to dispose of excess chlorine is to take it to a hazardous waste collection site and let the pros handle it.  

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