How Much Chlorine Should You Add to a Pool?

Why Your Swimming Pool Needs Chlorine  

Picture this: It’s a hot summer day, and your pool is packed with family and friends. Every time someone jumps in, they bring sunscreen and sweat with them. Chlorine works as a sanitizer by killing all of that bacteria, as well as viruses and algae. It works by binding with contaminants and neutralizes them, making the water safe for swimming. The key is keeping the right balance so it’s effective but not overpowering.  

What Type of Chlorine is Best For Your Pool?

Chlorine isn’t a one-size-fits-all chemical. Depending on your pool setup and maintenance routine, you might prefer one type over another.  

• Chlorine Tablets: This is the most common and easy-to-use form of sanitizing solution. Just pop chlorine tablets for pools into a floater, feeder, or skimmer basket to release over time.
• Chlorine Granules: This powdered form dissolves quickly and is perfect for making quick adjustments to balance the chlorine, including for shock treatments.
• Liquid Chlorine: Although liquid chlorine is typically used in commercial pools, it is powerful, fast-acting, and raises levels quickly. 

Each type of chlorine has pros and cons, but for most swimming pools, tablets are what we recommend you use. 

How Much Chlorine Should You Put in a Pool?

Maintaining chlorine in a pool depends on size and usage, as well as the type of chlorine you’re adding. Wondering how much liquid chlorine to add to a pool or how many chlorine tablets to use per week? The goal is to maintain a free chlorine level of 1-3 parts per million (ppm). 

Here’s a quick guide for how much chlorine to put in a pool to keep it clean and safe:  

• Chlorine Tablets: Put one 3-inch tablet per 5,000 gallons of water each week. How many you need depends on pool size. For example, a 20,000-gallon in-ground pool needs 4 tablets per week. 
• Chlorine Granules: Use 2-3 ounces (about 4-6 tablespoons) per 5,000 gallons. Remember that the amount you need will depend on your concentration, so test the water first! 
• Liquid Chlorine: Add ½ gallon per 5,000 gallons of water. So if you’re wondering how much liquid chlorine to put into a 15,000-gallon above-ground pool, it’s 1.5 gallons per week. 

Achieve balance and maintain chlorine in your pool by regularly testing levels 2-3 times per week, adjusting as needed, and shocking every 1-2 weeks — more on this later.

How to Lower Chlorine Levels in a Pool

Ever jump into the water and immediately feel your skin burn or your eyes sting? That’s usually a sign of too much chlorine. If you accidentally add too much, don’t panic. You can reduce chlorine in a swimming pool by: 

• Use the Sun: UV (ultraviolet) rays naturally break down chlorine, so uncover your pool and let the sunlight work its magic. Be sure to check the levels regularly until they hit 2-4 ppm.
• Dilute the Water: Partially drain your pool and then refill it with fresh water to help lower chlorine concentration.
• Try a Chlorine Neutralizer: If you need a quick fix, products like sodium thiosulfate can lower chlorine levels in mere hours. Just follow the package instructions.  

How Much Chlorine is Needed to Shock a Pool? 

If you’ve ever gone to swim and been hit with a strong "chlorine smell,” it’s actually not the chlorine itself but rather from chloramines, which are created when chlorine mixes with sweat, cosmetics, and other bodily fluids. If you get a whiff of this smell, it’s recently stormed, or your pool has been used a lot, it’s time to shock it. 

Start by raising your chlorine concentration to 10 ppm for both indoor and outdoor pools by adding 2 gallons of liquid chlorine per 20,000 gallons of water or using the granule package’s instructions for shock dosing. Although you could use chlorine tablets, they dissolve slowly and aren’t great for a deep clean. Then, wait until the levels drop to 2-4 ppm before swimming. 

Want a step-by-step guide? Read more about how to shock your swimming pool. 

How to Keep Your Pool Clean While Using Less Chlorine 

Whether you have sensitive skin or just want an alternative to traditional chlorine treatments, there are options available depending on your budget and pool type. 

As long as you don’t have a vinyl pool, one option is a saltwater system, which uses a salt cell to generate chlorine naturally, making the water feel softer and reducing chemical handling. You can also choose a mineral system, which uses silver and copper minerals to sanitize water with minimal chemicals or reduce the need for chlorine entirely by using ultraviolet light or ozone to kill bacteria and algae. 

Final Thoughts: How to Maintain Chlorine in a Pool Like a Pro

The best swim experiences don’t just happen; they start with water that’s clear, comfortable, and perfectly prepped. Keeping your chlorine just right comes down to three things: 

• Using the right type and amount of chlorine (2-4 ppm indoors, 3-5 ppm outdoors)
• Testing chlorine concentration and shocking regularly
• Having the right tools for easy pool maintenance

When you understand how different types of chlorine work and the right dosage for your pool size, you can avoid pesky problems like cloudy water, algae growth, and irritating chemical imbalances. 

But chlorine isn’t the only element of a pristine pool — circulation and cleaning are just as important. With the right balance of chemicals and a Maytronics robotic pool cleaner that scrubs surfaces, filters debris, and improves water flow, your swimming pool will always be ready for weekend parties, water aerobics, and more.