What Is the Correct Order for Pool Chemicals?

Owning a pool is a great way to enjoy the summer months, but it also requires regular care to ensure the water stays clean and safe for swimming. One of the most important aspects of pool care is knowing which chemicals to use and in what order to apply them. The order in which you add pool chemicals affects their effectiveness and helps keep your water balanced. In this post, we’ll explain the proper order for adding pool chemicals and why it matters.

Why the Order Matters

When you add chemicals to your pool in the wrong order, they may not work as effectively, or they may interfere with one another, potentially leading to imbalanced water chemistry. Following the right order helps ensure that each chemical performs as intended and creates a safer swimming environment. Additionally, it prevents wasted chemicals and minimizes damage to your pool equipment.

Common Pool Chemicals and Their Functions

• Chlorine: Sanitizes pool water by killing bacteria, viruses, and algae.
  

• pH Adjusters: Includes chemicals like pH increasers and decreasers that regulate the pool’s acidity.
  

• Alkalinity Increaser: Helps maintain stable pH levels by buffering against pH fluctuations.
  

• Calcium Hardness Increaser: Adjusts calcium levels to prevent scaling or corrosion.
  

• Algaecides: Prevents and controls algae growth.
  

• Cyanuric Acid: Protects chlorine from breaking down due to UV rays.
  

• Pool Shock: A concentrated chlorine treatment for extra sanitation.
  

Now, let’s go over the best order for adding these chemicals to your pool.

1. Test the Pool Water

Before adding any chemicals, it’s crucial to test your pool water. Testing the water gives you a clear picture of its current chemical levels and helps you determine which chemicals need to be adjusted. Use a pool testing kit to measure the following:

• Chlorine: 1.0 to 3.0 ppm
  

• pH: 7.4 to 7.6
  

• Alkalinity: 80 to 120 ppm
  

• Calcium Hardness: 200 to 400 ppm
  

• Cyanuric Acid: 30 to 50 ppm
  

Once you’ve tested the water, you’ll have a better idea of which chemicals to add and in what quantity.

2. Adjust pH Level First

The pH level of your pool water is one of the most important factors in determining how well your chemicals will work. If the pH is too high (alkaline), it can reduce chlorine efficiency, leading to cloudy water. If the pH is too low (acidic), it can cause skin irritation, eye discomfort, and damage to your pool surfaces and equipment.

Why pH Should Be Adjusted First

Adjusting the pH should be your first step because it affects the efficiency of all other chemicals, including chlorine. If the pH is not within the correct range, the chlorine won’t be able to sanitize the water effectively, and other chemicals may not work as intended.

• To raise pH: Use a pH increaser like soda ash or sodium bicarbonate.
  

• To lower pH: Use a pH decreaser, such as muriatic acid or sodium bisulfate.
  

Ideal pH Level

The ideal pH range for pool water is between 7.4 and 7.6. Regular testing ensures the water stays within this range, promoting better chemical efficiency.

3. Add Alkalinity Increaser

Total alkalinity plays a critical role in stabilizing the pH levels of your pool. It acts as a buffer to prevent rapid pH changes, which can be harmful to both the pool water and swimmers.

Why Add Alkalinity Increaser After pH?

After adjusting the pH, the next step is to stabilize it with an alkalinity increaser. Alkalinity helps prevent the pH from fluctuating too much, which makes it easier to maintain consistent water chemistry.

• Ideal Alkalinity: 80 to 120 ppm
  

If your alkalinity is too low, it can cause pH levels to become unstable. Adding an alkalinity increaser (usually sodium bicarbonate) will buffer the pH and stabilize the water’s acidity.

4. Add Calcium Hardness Increaser

Calcium hardness refers to the concentration of calcium in your pool water. Having the correct calcium level is essential to prevent damage to your pool surfaces and equipment. Low calcium levels can cause corrosion, while high levels can result in scaling.

Why Add Calcium After Alkalinity?

After stabilizing the pH and alkalinity, the next step is to adjust calcium hardness. Adding calcium hardness increaser at this point ensures that your pool water is properly balanced before other chemicals are introduced.

• Ideal Calcium Hardness: 200 to 400 ppm
  

If calcium hardness is too low, you can add a calcium hardness increaser to raise it. This will help prevent equipment damage and ensure that the water is in optimal condition.

5. Add Cyanuric Acid (Stabilizer)

Cyanuric acid is essential for protecting chlorine from being broken down by the sun’s UV rays. Without cyanuric acid, chlorine dissipates too quickly, leaving your pool water vulnerable to bacteria and algae.

Why Add Cyanuric Acid After Calcium?

Cyanuric acid is typically added after calcium hardness because it helps protect the chlorine, and it doesn’t interact with other chemicals in a way that would reduce their effectiveness. By adding cyanuric acid at this point, you ensure that your chlorine remains effective even in direct sunlight.

• Ideal Cyanuric Acid Level: 30 to 50 ppm
  

Add cyanuric acid slowly and test the levels regularly to maintain proper stabilization of chlorine.

6. Add Algaecide

Algaecides are chemicals used to prevent and control algae growth in the pool. Chlorine is effective against algae, but algaecides offer additional protection, especially in warmer climates or pools with poor circulation.

Why Add Algaecide After Cyanuric Acid?

Adding algaecide after cyanuric acid helps ensure that the pool water is fully stabilized. Algaecides are designed to work effectively when the water’s pH, alkalinity, and chlorine levels are already balanced.

• When to Use Algaecide: Regularly, especially in warm weather or if you’ve had problems with algae in the past.
  

7. Pool Shock (Optional)

Shocking your pool is a process that involves adding a high dose of chlorine to eliminate contaminants and sanitize the pool water more effectively. Pool shock is typically used after heavy pool usage, a pool party, or when the water appears cloudy or dirty.

Why Shock Last?

Pool shock should be the final step in the process. Since it is a high-dose treatment, shocking your pool at the end of the chemical process ensures that the water is ready to handle the strong chlorine dose and allows other chemicals to work without interference.

• Types of Pool Shock: Calcium hypochlorite, sodium dichlor, and lithium hypochlorite are the most common types of pool shock.
  

How Often to Shock the Pool

Shocking the pool should be done every 1-2 weeks or whenever the water appears off-balance. It’s also a good idea to shock the pool after a large gathering or after a lot of swimming.