Pierfrancesco Fagiani
Pool Senior Consultant

27/01/2026

One of the questions we are most often asked concerns pool water disinfection: is it better to choose salt sterilisation or chlorine?

In this article, I want to offer a clear and concise overview, explaining the main advantages and differences between the two most popular pool sterilisation solutions. If you would like to explore the topic further, we can do so together during our in-person meeting.

 

WATER PURIFICATION

First of all, it is important to know that pool water is kept clean in two ways:

  1. Mechanical cleaning

  2. Chemical treatment

Both are necessary, and one does not replace the other.

Mechanical purification is done through the filter, which traps physical impurities such as insects, small debris, leaves, hair, and similar particles. Different materials can be used inside the filter: sand, quartz, glass, or polyester fiber. Sand is the most common, although not the most efficient: it traps particles of 40–60 microns, while other systems can capture 3–10 microns (one micron equals one-thousandth of a millimeter).

Chemical purification consists of disinfecting the water using chemical products that eliminate bacteria and microorganisms. This process relies on two main factors: pH and the concentration of the disinfectant, such as chlorine.

pH is fundamental: if it does not remain within the correct range (7.0–7.4), chlorine and other disinfectants do not work properly.

The addition of chemical products can be done manually or automatically:

Manual: values are checked using a test tube immersed in the water for a few seconds. This allows you to determine if and when to add the products.

Automatic: a control unit independently reads pH and chlorine levels and doses the necessary chemicals based on the measurements.

Now that we have clarified these fundamental concepts, we can go into more detail!

 

MANUAL OR AUTOMATIC STERILIZATION?​

Besides the fact that it is no longer necessary to add chemicals to the pool manually (which is already a big advantage!), an automated control unit offers the great benefit of maintaining a constant level of water disinfection. In contrast, manual management tends to create more pronounced peaks or drops in chlorine levels.

For this reason, whenever possible, I recommend my clients choose an automated system for water disinfection.

 

LIQUID CHLORINE UNIT​

There are different types of automatic control units; the simplest is the pH/chlorine unit, which reads the pH and chlorine levels and, drawing the chemicals from the dedicated containers, releases them directly into the pool.

 

SALT UNIT

In this case, salt is added to the pool once a year. When the water passes through the control unit, an electrolytic process occurs that breaks down the salt into various compounds, including hypochlorite, the same disinfecting agent found in chlorine. This is then released into the water, ensuring its sterilization.

 

WHAT IS THE DIFFERENCE BETWEEN A SALTWATER AND  A CHLORINE UNIT?​

 

  1. With chlorine sterilization, there are two tanks connected to the control unit: one to regulate the pH and one for chlorine. With salt sterilization, however, only the pH tank is present.
  2. With the salt system, the water has a slight salty taste, generally more pleasant (about 3–4 grams per liter, compared to 30 grams in seawater).
  3. Another advantage concerns cyanuric acid. With chlorine tablets or powder, this compound accumulates over time. Cyanuric acid is necessary to protect chlorine from sunlight, but it can be irritating. In tablets, only part of the cyanuric acid serves as sun protection; the rest accumulates, and if the concentration becomes too high, it can even inhibit chlorine’s effectiveness. With salt sterilization, this problem does not occur.
  4. Furthermore, the quality of the disinfecting agent is ensured in a salt system because the chlorine is produced directly from the electrolysis of salt. In contrast, liquid, powdered, or tablet chlorine can contain impurities or unwanted substances, especially if sourced from unreliable suppliers. For this reason, at Professione Piscina, we use only high-quality, safe, and controlled products, even if they are more expensive.
  5. Finally, those using liquid chlorine must consider that it can lose effectiveness over time (even if unopened), a phenomenon known as “losing its strength,” which makes disinfection less efficient.

 

OTHER TYPES OF STERILIZATION

There are also other pool sterilization methods that minimize chlorine use or, in some cases, eliminate it completely. These include systems using copper, magnesium, active oxygen, electrolysis, hydrolysis, and UV rays, each with its own characteristics and advantages. You can learn more at this link.

In any case, regardless of the chosen sterilization system, it is always necessary to carry out so-called shock treatments at the beginning of the season, at regular intervals during the season, and at the end of the season to ensure maximum water hygiene.

 

HOW MUCH DOES A STERILIZATION CONTROL UNIT COST?

The cost of a pool sterilization control unit varies depending on the type of system, the features offered, and the size of the pool. The simplest units, dedicated to controlling pH and chlorine, have an indicative price ranging from €3,500 to €4,000 and are ideal for medium-sized pools. These systems automatically monitor water values and dose the necessary chemicals, avoiding frequent manual intervention.

Salt chlorination systems have a higher initial cost compared to traditional pH/chlorine systems. Prices usually range from around 1,000 to over 1,700 euros, depending on features and capacity. The advantage is that, by producing chlorine directly from salt dissolved in the water, they reduce the need to buy external chemical products, such as liquid or tablet chlorine. However, it is important to consider that the electrolytic cell needs to be replaced every 2–3 years, a cost that partly offsets the savings on chemicals. More complete versions, with automatic pH control and an integrated dosing pump, can reach prices around 1,300–2,100 euros.

Investing in a quality control unit ensures consistently clean and safe water, reduces chlorine peaks, and maintains a constant disinfection level, improving comfort and safety for pool users. Prices may vary depending on the retailer, pool size, and required features, so it is always advisable to request a personalized quote to choose the solution best suited to your needs.

 

CONTACT US TO CHOOSE THE BEST STERILIZATION SYSTEM FOR YOUR POOL

We operate in the Marche, Umbria, and Abruzzo regions. Thanks to our extensive experience in the pool sector, we are able to identify the best sterilization system and customize it to meet the specific needs of each client.

If you would like to learn more and receive personalized advice on the system best suited for your pool, contact us to schedule an appointment. We will answer any questions you may have and guide you step by step in making the most effective and safe choice.

Please note that the sterilization system can also be installed in existing pools, allowing you to upgrade and improve your pool without major modifications.

Don’t miss the opportunity to have a perfectly sanitized pool tailored just for you: we look forward to hearing from you!

 

What is the difference between a saltwater sterilization system and a chlorine system?

The difference between a saltwater and a chlorine system is how chlorine is produced. A saltwater system generates chlorine through the electrolysis of salt dissolved in the water, keeping the pool disinfected without needing large amounts of added chlorine. The water still contains chlorine, so it is not completely free of this chemical.
A traditional chlorine system requires manually adding liquid, powder, or tablet chlorine. Both systems require monitoring pH and chlorine levels, but a saltwater system reduces the need for manual chemical handling.

Are saltwater pools completely chlorine-free?

No, saltwater pools are not completely chlorine-free. Chlorine is produced naturally through the electrolysis of salt dissolved in the water, keeping the pool clean and disinfected. This reduces the need to add external chlorine, but chlorine is still present and necessary for proper water hygiene.

Can I convert a chlorine pool into a saltwater pool?

Yes, you can convert a chlorine pool into a saltwater pool by installing a salt chlorinator and adding the correct amount of salt to the water. The installation should be done by a professional to ensure the system works correctly and keeps the water properly disinfected.

What are the alternatives to chlorine for pool sterilization?

Alternatives to chlorine for pool sterilization include active oxygen, ozone, UV rays, and more. Active oxygen cleans the water without leaving chemical residues, ozone purifies without adding external chemicals, UV rays kill bacteria and viruses. Each method has advantages and limitations, and the choice depends on the pool’s needs and budget. You can learn more about this topic by reading this article.

How much does it cost to install a pool sterilization system?

The cost of a pool sterilization system depends on the type and features of the system. An automatic pH and chlorine system costs around €3,500–4,000. A saltwater system costs €900–1,500 for basic models and up to €2,100 or more for complete versions with automatic pH control. It is always recommended to request a personalized quote to find the best solution for your pool.

What is the difference between a manual and an automatic pool sterilization system?

The difference between a manual and an automatic pool sterilization system is how chemicals are added and pH and chlorine levels are controlled. With a manual system, you must measure water values and add chlorine or other chemicals as needed. With an automatic system, a control unit continuously measures pH and chlorine and adds the chemicals automatically. This keeps the water balanced, reduces spikes or drops in chlorine, and makes pool maintenance easier.