Today more than ever, pool hygiene and cleanliness are highly relevant topics. A pool is not just a design element, but a true space of well-being.
Although chlorine is the most common traditional method, more and more people are looking for a superior swimming experience, one that is healthier and gentler on the skin. Thanks to technological progress, it is now possible to choose a chlorine-free water treatment, turning the pool into an oasis of luxury and personal well-being, fully in line with the Professione Piscina standard.
Is chlorine harmful?
Many people associate chlorine in water with something negative, mainly because of its characteristic unpleasant smell. It is, however, a complex and nuanced topic.
In the case of a swimming pool, it is important to remember that the proper use of chlorine ensures a high disinfecting power and provides stability over time in daily use. From the 1980s until more recently, many people experienced chlorine when visiting public pools or water parks, often finding themselves surrounded by its strong odor.
The reason why chlorine sometimes has such an intense smell is poor management of its dosage and control in the water; when handled correctly, this problem generally does not occur. Finally, it is worth noting that even regular tap water contains a small amount of chlorine to ensure its safety.
Salt and Magnesium Sterilization
Those who own a salt or magnesium control unit should not be under the illusion that the water is completely chlorine-free: in these systems, the salt or magnesium is broken down into hypochlorous acid, which is still a form of chlorine. There are some differences between a salt or magnesium control unit and a pure chlorine one, especially in terms of ease of use, but even this type of sterilization does not completely eliminate the presence of chlorine.
SALT STERILIZATION (OR SALT ELECTROLYSIS)
Salt sterilization (or salt electrolysis) is based on the use of an electrolyzer that converts the salt (NaCl) dissolved in the water into free chlorine (hypochlorous acid), the main disinfecting agent, leaving the water slightly saline. This process occurs continuously and automatically, reducing the need to manually add chlorine.
This automatic production is also called “local chlorine,” since it takes place directly in the pool, and there is no need to buy new chemical containers to keep the water clean. This saves valuable time and avoids the risk of purchasing low-quality products or products that lose effectiveness over time.
Usually, the product (salt = sodium chloride) is added at the beginning of the season (with a small top-up mid-season if necessary), and then the control unit automatically manages the release of the addition to the pool of the correct amount of disinfectant (i.e., chlorine produced from salt) and of product to adjust the pH.
There are costs to consider: although this system reduces spending on chemicals, every two to three years it requires significant maintenance operations, such as replacing the probes and the cell. These interventions vary depending on the pool size and usage and generally range between €1,500 and €2,500.
MAGNESIUM STERILIZATION
Magnesium sterilization is a more advanced system compared to salt and works in a similar way: The main difference is that, instead of sodium chloride, magnesium chloride is added to the water, from which the chlorine needed for sterilization is still produced.
The benefits of this type of sterilization are clear: magnesium ensures a gentler and more pleasant swimming experience, leaving the skin soft and the hair silkier and less damaged.
The cost of this system is, however, much higher than salt-based systems, generally 8–10 times more. Both systems operate with the same type of control unit, allowing you to choose, year by year, whether to use the unit with salt or with magnesium, depending on your needs and preferences.
So, is it possible to have a completely chlorine-free system?
Yes, it is possible.
Although the use of chlorine, when applied correctly according to certain rules, is not harmful to people, the ability to sterilize water without any presence of chlorine (and therefore without any chemical substance) is certainly an important and advantageous achievement made possible by technological advances in recent years.
Since we always strive to be at the forefront and offer the best to our clients, we are pleased to delve into the topic of the new frontiers in pool sterilization.
What are the chlorine-free sterilization methods?
Here are the main available systems that use minimal amounts of chlorine, or none at all:
THE UV SYSTEM
UV rays represent a physical method of sterilization: water passing through the lamp is treated by destroying the DNA of bacteria, viruses, and algae. It is an ecological and safe system, ideal for reducing the presence of microorganisms without using chemical substances.
The most efficient equipment can eliminate up to 99% of bacteria, viruses, and similar organisms. However, an important limitation should be noted: They sterilize only the water that passes through the lamp. Since no disinfectant is injected directly into the pool, some forms of life can survive inside the pool.
Bacteria, viruses, and algae can adopt strategies to resist, such as forming colonies near pool fittings (nozzles, corners, lights) or attaching to walls to create a slippery biofilm, thereby avoiding being drawn into the circulation system.
For this reason, the use of UV rays should be integrated with another disinfection system, such as oxygen or a minimal dose of chlorine, to ensure complete protection of the pool water, both during passage through the filter and within the pool itself.
COPPER TREATMENT
Copper treatment is a technology that uses copper electrolysis to combat bacteria, algae, and other microorganisms. This system allows a reduction in chlorine usage, making the water gentler and more pleasant.
In recent years, copper treatment has continued to be highly appreciated, especially for its effectiveness against biofilm and resistant algae, as well as for the long-lasting presence of copper in the water, which helps reduce the frequency of maintenance operations.
However, European regulations are becoming increasingly attentive to the environmental impact of copper, which may be considered potentially polluting when present in high concentrations. In addition, this system requires careful management, with constant monitoring of copper concentration and pH levels to avoid stains, discoloration, or compatibility issues with certain pool finishes.
For these reasons, although there is currently no ban in force, it is possible that copper treatment will be used less and less in the future, also because more modern and easier-to-manage alternatives now exist, such as UV systems, salt electrolysis, or hydrolysis.
HYDROLYSIS
Hydrolysis is a system for cleaning pool water that uses electricity to automatically create disinfecting substances directly from the water itself. The process takes place thanks to a titanium electrode, which generates the electrical reaction necessary for the treatment. In this way, the use of chemical products is reduced and the water becomes cleaner and more natural.
It is important to know that ions do not eliminate all the organic matter introduced by bathers, such as sweat or cosmetic residues. For this reason, according to regulations, a small oxidizing support is still necessary, often chlorine in very low quantities, sufficient to complete the disinfection process without causing odors or irritation.
Installation is more expensive compared to other automatic systems, such as salt electrolysis or UV systems, but it is worth highlighting that, according to numerous studies, the hydrolysis process can be up to three times more effective than traditional chlorine-based treatment.
This system is commonly appreciated in high-end swimming pools or in contexts where the goal is to minimize the use of chlorine, providing water that is gentler on the skin and eyes.
OZONE
Ozone sterilization uses O3 gas to oxidize and destroy bacteria, viruses, and microorganisms present in the water. Ozone is a highly effective and fast-acting natural disinfectant that cleans the water without leaving chemical residues.
In ozone systems, it is still recommended to use a minimal amount of chlorine or another oxidizer as support, because ozone does not leave a stable disinfectant residual. This ensures the safety of the water between treatment cycles.
Another important aspect of ozone is that it effectively eliminates unpleasant odors and tastes in the water, improving the overall quality of the pool and making the swimming experience more enjoyable.
OXYGEN
The treatment commonly referred to as “oxygen-based” is actually based on two types of oxidizing products: potassium monopersulfate, known as granular oxygen, and hydrogen peroxide, the familiar liquid disinfectant. It is therefore not the oxygen we breathe, but compounds that release active oxygen in the water.
This method represents one of the most natural and gentle solutions for sterilizing pool water without using conventional chlorine. It does not introduce harsh elements for humans, making it particularly suitable for those seeking a purer and more comfortable swimming experience.
However, oxygen has a less intense and shorter-lasting effect compared to traditional chemical disinfectants, so it requires closer supervision. It is not recommended for use alone in heavily used pools or under demanding conditions, but in the right circumstances, it can provide effective and stable disinfection.
This treatment is highly valued in indoor pools, where the absence of strong odors and its gentleness on the air of enclosed spaces make a difference. It is increasingly sought after in high-end outdoor pools as well, where maximum water quality and clarity are desired.
Currently, there are no affordable and widely available units capable of automatically measuring the concentration of active oxygen (peroxide) in the pool; the equipment that can do this is very expensive. For this reason, treatment management is generally carried out manually, following simple but precise procedures.
How much does the material used inside the filter matter?
A lot. To move toward a “chlorine-free” approach, it is essential to use modern, high-performance filter materials rather than traditional sand or quartz. Conventional sand traps impurities down to 40–60 microns (a micron is one-thousandth of a millimeter), while advanced materials such as glass, polyester, or diatomaceous earth can capture particles as small as 2–3 microns.
This means that even very small organic particles, such as bacteria, can be caught by the filter, making chlorine-free sterilization possible. As mentioned earlier, this type of treatment is more delicate to manage than chlorine and therefore requires careful monitoring and maintenance to ensure effectiveness.
An additional advantage of such advanced filtration is the undeniable aesthetic impact: the water appears clearer, brighter, and more sparkling, enhancing the pool visually as well. After all, the eye wants its share too.
What is the best alternative sterilization system to chlorine?
The answer depends on several factors. Choosing the most suitable system for your pool must take into account variables such as the type of pool (indoor or outdoor), its size, frequency of use, desired average temperature, period of use, willingness to follow the maintenance procedures required by alternative systems, and, of course, the available budget.
How to make the right choice
It is not easy to decide on your own: choosing the ideal chlorine-free sterilization system requires experience and specific knowledge. This article aims to provide only a general idea and answer the most common questions from clients.
During our Pool Professional Consulting® consultation, we will analyze all these factors together, evaluating your needs, the characteristics of your pool, and your preferences. We will explore every aspect to identify the most effective and tailored solution, leaving nothing to chance.
If you want the certainty of a safe result, rely on those with consolidated experience: with our professionals, you can choose the perfect chlorine-free disinfection system for your pool, with a guarantee of quality and safety.
NOTE: This article refers to private pools. For public pools (municipal pools) and those in hospitality facilities (restaurants, gyms, hotels, etc.), the law requires a certain amount of chlorine in the water to protect swimmers’ health. Even in these cases, however, innovative solutions can be developed to limit chlorine use.
