Biological pools: everything you need to know, advantages, types, and care

Biological swimming pools, also known as biopools or natural pools, represent a revolution in the design and concept of outdoor bathing. These facilities allow you to immerse yourself in an aquatic environment perfectly integrated with nature, without the need for chemicals like chlorine or harsh artificial systems. They are built using natural materials and rely on the purifying action of aquatic plants, microorganisms, and substrates, thus creating a healthy, sustainable, and visually harmonious environment.

In recent years, interest in this type of pool has grown exponentially, especially among those seeking a more ecological and environmentally friendly alternative. Swimming in freshwater, surrounded by flora and fauna, provides a relaxing, therapeutic experience that is much more pleasant for the skin, eyes, and respiratory system. This trend continues to evolve thanks to innovation in landscaping and outdoor architecture.

What is a biological pool?

A biological swimming pool is an artificial aquatic ecosystem designed to allow bathing in optimal hygienic and comfortable conditions without the use of chemicals. It consists of two main zones: the bathing area and the regeneration or biological filter zone. The latter includes aquatic plants, gravel, and various materials that allow for the natural purification of the water, mimicking the functioning of a healthy lake or pond.

Unlike natural ponds where swimming is possible, these pools have a clear physical separation between the two areas , which facilitates maintenance and prevents aquatic life from interfering with bathers. The water circulates continuously between the two spaces, allowing it to be constantly filtered and oxygenated.

The result is crystal-clear water, free of chlorine odor and itching , with the sensation of immersing oneself in a natural environment. Furthermore, natural swimming pools do not need to be drained in winter , blend seamlessly into the landscape, and can become a true haven for biodiversity.

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History and evolution of natural pools

The origin of natural swimming pools dates back to the early 1980s in Austria, where they began to be called Schwimmteich . The first biopool was built by Werner Gamerith in his own garden. Following this initiative, pioneering companies such as Biotop Landschaftsgestaltung and BioNova promoted the commercialization and technological development of this model in Europe.

Over time, the concept has expanded internationally . Germany, Switzerland, France, the United Kingdom, Italy, and Spain quickly adopted these solutions in both private and public facilities. In a short time, thousands of natural swimming pools have been built throughout Europe, adapting to different garden styles and needs. In Latin America, Mexico, Uruguay, and Chile also lead the way in the construction of natural swimming pools, contributing to the globalization of this ecological bathing system.

Operation of biological pools

The key to biological swimming pools lies in their natural filtration system . The water is purified through a series of biological and mechanical processes, completely eliminating the need for chemicals. Water circulation between the swimming area and the regeneration zone is achieved using low-consumption pumps or, in some cases, by inertia thanks to the sloped design.

In the regeneration zone, oxygenating and purifying aquatic plants such as irises (Iris pseudacorus, Iris sibirica), bulrushes (Scirpus holoschoenus), cattails (Typha laxmannii), and other marginal species adapted to the local environment are planted. These plants absorb nutrients that would otherwise promote algae growth and contribute to the biological balance of the system.

The water flows through gravel and substrates that retain particles and encourage the growth of beneficial microorganisms, which break down organic matter and eliminate contaminants. The result is a closed, self-balancing, and toxic-free circuit that keeps the water clean, clear, and ready for swimming year-round.

Some biological pools also include fish —such as carp or native species—to help control mosquito larvae and small algae, provided the climate and conditions permit. The presence of aquatic life is a clear indicator of the system's purity and health.

Characteristics and types of biological pools

Biological swimming pools can be adapted to a wide variety of spaces, climates, and styles. Their size varies, from small shelters to veritable bathing lakes. These are the main types :

• Natural poolThey usually have a bathing area separated from the regeneration zone by submerged walls; aquatic plants filter and purify the water naturally. The minimum recommended surface area is usually 40 m².
• Living pool: It is visually similar to a classic pool, but uses biological filtration systems, with or without plants, depending on the chosen design.
• Hybrid pool: Combines aquatic plant purification with advanced filtration technology, providing more swimming space and less regeneration area.
• Swimming pond: No concrete, with earth walls and a higher proportion of planted area, which reduces costs and creates an ideal refuge for wildlife.

Biological swimming pools allow great flexibility in design : they can be formal, contemporary, naturalistic or minimalist, with finishes in stone, wood or vegetation, and adapted to any environment and aesthetic preference.

Materials and construction of a biopool

The construction process of a natural swimming pool involves several essential phases, always seeking maximum integration with the landscape and minimal environmental impact . The most common steps are detailed below:

1. Excavation and profiling of the terrain: It is carried out according to the chosen design, ensuring the separation between the bathing area and the filtration/regeneration area.
2. Removing unwanted elementsStones, roots and other foreign bodies are removed so as not to damage the layers below.
3. Preparation of the fund: A sand base is applied, followed by a protective layer that prevents damage to the waterproofing.
4. waterproofing: A sheet of polyethylene, EPDM or other compatible material is generally used to prevent water leaks.
5. Installation of pumps and circulation systems: They allow the flow of water between both areas, ensuring oxygenation and the effectiveness of the natural purification process.
6. Planting vegetation in the filtration zone: Species adapted to the climate and water quality are chosen, prioritizing non-invasive native flora.
7. Finishes and decoration: Platforms, piers, terraces or natural sandy beaches can be added optionally to enhance the landscape integration.

The internal biological balance usually stabilizes after the first two or three years, although the pool is functional and suitable for swimming from the moment it is opened.

Advantages and benefits of biological pools

The rise in popularity of biopools and natural swimming pools is due to a combination of environmental, economic, and health advantages that make them superior to conventional swimming pools in many aspects.

• Health & Wellness: The water is free of chlorine, salt, and chemicals, which prevents irritation to the skin, eyes, and mucous membranes, and reduces the risks for people with allergies or skin problems.
• Respect for the environment: Natural materials and processes ensure minimal environmental impact and contribute to the creation of a small ecosystem in the garden.
• Reduced consumption of resources: There's no need to empty the pool every year, which saves water. Energy maintenance is also reduced.
• Biodiversity: Biopools attract beneficial wildlife such as frogs, dragonflies, butterflies, birds, and small invertebrates. By including native fish, the proliferation of mosquito larvae is controlled.
• Aesthetics and landscape value: Their integration into the environment allows them to be authentic decorative elements all year round, even in winter.
• Universal access: They can be built even in areas with environmental regulations that prohibit conventional swimming pools.
• Easier maintenance: Simply vacuum the bottom and periodically clean the regeneration area, removing organic and plant debris.
• Greater sustainability: They allow the use of renewable energy for pumps and circulation systems, further reducing the ecological impact.

Maintenance and care of a biopool

Contrary to what many believe, the maintenance of a biological pool is less demanding than that of a traditional pool , but it does require certain care to guarantee the stability of the ecosystem.

• surface cleaning: It is important to regularly remove leaves, insects, and plant debris from the water surface to prevent them from decomposing at the bottom.
• Algae control: Aquatic plants help prevent excessive algae growth, but it's a good idea to inspect the walls and manually remove any algae that may appear.
• Pruning and maintenance of plants: It is done once or twice a year to maintain balance and prevent invasive species from dominating the system.
• Checking pumps and recirculation systems: It is recommended to periodically check its operation, especially before the bathing season.
• Seasonal care: In winter, it's not necessary to empty the pool, but it may be helpful to cover it with a tarp to prevent the accumulation of leaves and debris. The circulation pump can be turned off if the water isn't freezing, and the water level should remain stable.

It's worth remembering that the biopool is a living system: its appearance, water color, and biodiversity will vary depending on the season and environment, making it an ever-changing spectacle.

Decoration and customization of biological pools

Design versatility is one of the greatest advantages of biological swimming pools. They can be seamlessly integrated into any garden, whether small or large, and adapted to each homeowner's tastes. Options exist for all styles, from formal designs with stone borders and paved terraces to naturalistic proposals where the vegetation and topography dictate the shape of the aquatic environment.

It is essential to respect the ecological essence of the pool, opting preferably for certified natural materials and native flora , and avoiding elements that are harmful to the ecosystem. Wooden platforms, natural stone steps, or small compacted sand beaches can be incorporated into the bathing area for an even more sensory experience. The edge can be finished with marginal plants or decorated with ornamental aquatic elements, such as water lilies.

The selection of plant species should consider differences in height and flowering season, colors, and textures that complement the visual composition throughout the year. It's also possible to install water jets, waterfalls, or decorative fountains, which also promote oxygenation and make the overall landscape more attractive.

Aspects to take into account before building a biopool

Before embarking on the construction of a biological pool, it is essential to analyze several key factors:

• Dimensions and intended use: It is necessary to calculate the volume of water according to the number of people who will use it and whether fish or other animals will be included.
• Location: An area with sufficient sun exposure should be chosen to encourage plant growth and prevent excessive cooling outside of the bathing season.
• Choice of plant species: It is recommended to use local species adapted to the climate and avoid invasive plants that can destabilize the ecosystem.
• Maintenance: Learn about the necessary routines and plan for regular care.
• Budget and legal requirements: The initial cost may be higher than that of a conventional pool, but the savings in the medium term are significant. In protected areas or with planning restrictions, check the regulations before starting construction.

Disadvantages or challenges of natural pools

While natural swimming pools offer numerous benefits, it is important to be aware of some challenges or limitations :

• The water will not always be completely clear., being able to acquire green or brown tones depending on the vegetation and the chosen background.
• Possible appearance of algae and mosquitoes If there is no adequate biological balance or if inappropriate plant or animal species are chosen.
• Need for more space, since the regeneration zone usually requires at least 30% of the total surface area.
• The life cycle can take months to stabilize., especially in the early years.
• Requires vigilance to avoid nutrient overload (for example, urine or excess organic debris), which can cause the occasional development of algae.

However, most of these problems can be prevented or corrected with proper design and maintenance, and by consulting with specialized professionals.

Frequently asked questions about biological pools

• Can biopools be installed in any climate? Yes, although species selection must be tailored to local conditions and sun exposure to ensure ecosystem success.
• What is the minimum size of a biological pool? There is no one size fits all, but it is common to start from about 20-40 m², depending on the needs and available space.
• Can traditional pools be transformed into biopools? Yes, there are adaptation systems that allow you to transform a conventional pool into a biological one, incorporating plant areas and modifying the purification system.
• Is it advisable to keep fish in a biological pool? It is possible and beneficial, as long as appropriate species are chosen and the ecological balance is controlled so as not to harm water quality.
• How much does a biopool cost? The budget varies depending on size, design, materials, and finishes, but the investment pays off in the medium term thanks to low consumption and maintenance.

Choosing a biological swimming pool means opting for a healthy, sustainable bathing experience connected to nature . It's an investment that transforms your garden into a living oasis, promotes biodiversity, and creates a therapeutic space that evolves with the seasons. The experience of swimming in pure water, surrounded by flora and fauna, marks a turning point in outdoor enjoyment.