Biophilia —that instinctive impulse that encourages humans to seek connection with nature as a way to feel good— is a kind of natural medicine that is here to stay after the experience of confinement during the worst of the pandemic. In an increasingly technological environment, promoting deep sensory interaction with plants, animals, minerals and any other manifestation of the natural world is a proven therapeutic habit. It can be done with simple formulas —go on a picnic, to a country house, to watch the sunset or simply walk through a park or grow plants on the balcony— or as sophisticated as you want. Who has not heard of the benefits of hugging trees, attending flower arrangement workshops or meditating while focusing on listening to the hundreds of sounds that are hidden in the silence of the forest or in the sound of the sea?
In the middle of summer, after four heat waves and on and on, that yearning for less is more takes shape in pools camouflaged in lakes or ponds. And what begins as a trompe l’oeil ends as the most ecological and evocative expression in our search for connection with nature. In Spain, natural pools abound in the courses of some rivers (there are authentic river paradises in the regions of La Vera, the Sierra de Gata and the Ambroz valley, in the north of the province of Cáceres). Countries like Germany are pioneers in this practice – a good example is the Heigenbrücken natural pool, which has been in operation since 1928. Old conventional swimming pools are also being naturalized to convert them into spaces for biodiversity and recreation in which, around the pure water, dynamic aquatic ecosystems are unleashed.
In recent years, thanks to boom From landscaping to the design of leisure spaces, many hotels have built impressive natural pools —also called bio-pools—. To name just a few, there is the agrotourism More Ardevol, on the Costa Daurada (Catalonia); the farm The Jument Verte, in the town of Aix-Les-Bains (France); he Naturhotel Edelweiss Wagrain, in Austria; or the country hotel Scarlet, in Cornwall (England). “The sensation of bathing in a natural pool is very different from doing so in a conventional one,” say the landscape designers María Barceló and Xoan Pérez, from Studio MIX Landscaping. “The palette of deep greens loaded with nuances in the background, the touch and aroma of the surrounding vegetation, the sound of fluttering birds and insects convey the sensation of being in a small natural lake.”
A space in balance
The key to natural pools is ecological balance. Schematically, they consist of a bath vessel next to which there is a regeneration area, essential for the water to remain purified without the need for chlorine, chemicals, ultraviolet light or ultrasound, and without having to control the pH balance of the water. artificial way. The water must be in motion, circulating between the bathing area and the regeneration area. It can be driven towards the latter by means of a pump or by inertia. As in natural wetlands, colonies of bacteria spontaneously arise in this pure water, allowing it to remain clean in a self-sufficient way.
The regeneration space must include a physical filtering area (composed of sand and gravel of different sizes that retain leaves, dust, hair and any floating element), and the plants themselves, which function as a biological filter. It is the vegetables that purify the water thanks to the fact that they absorb nitrates and provide oxygen through the roots in the substrate, preventing it from being corrupted. The water is alive and harbors a legion of beneficial bacteria and microorganisms that break down the dirt that would end up spoiling it.
There are many suitable species, both submerged and marginal, that can be planted in a natural pool. “In Spain the most common are lilies (Iris pseudacorus, Iris sibirica)the rushes (Scirpus holoschoenus)the cattail (Typha laxmannii) and certain buttercups”, says Enric Sancho, director of cultidelta, a nursery specialized in native and Mediterranean plants. “But in the plant world you can never generalize. The viability of the species will depend on the geographical location and the quality of the water”, warns the nurseryman. “You have to be very careful not to choose invasive species. For example, certain species of cattails and reeds—such as the Typha latifolia, the Typha angustifolia or the Phragmites australis— they have very vigorous rhizomes that could occupy the entire space and generate a monoculture, so I would rule them out”, he warns. “It is better to use eneas of contained size —such as the Typha laxmannii, the Typha minimahe Juncus inflexus— or colorful floral herbaceous plants such as Marsh Iris”.
Plants and bugs… naturally
The exposure of the pool to the sun determines the life that will be generated in the water. “Any area of the Peninsula can be suitable for installing a bio-pool, as long as it is taken into account that the more heat and insolation, the greater the possibility of the appearance of algae. And, depending on the species chosen, also more mosquitoes”, indicates Enric Sancho. It is important to assume that these things can happen. And, in such a case, renew the water when necessary.
The planting scheme must be well studied so that there are species with and without flowers, different textures —more herbaceous, more woody…— and various shades of green that complement each other and help the construction blend in with its surroundings. “The color that the water will project is another element to take into account and it can be modulated depending on the internal material of the glass,” they explain in Estudio MIX. Another very expressive element are the water jets. “Something that differentiates natural pools from traditional ones is the sound of the water. A jet can be installed that, in addition to helping with the oxygenation of the pool, works as a lure, attracting the attention of whoever approaches it”.
Being a living element, the natural pool is much more than a bathing facility: it is an aesthetic event that reflects the cycle of the seasons. In summer, the plants emerge from the water creating an enveloping sensation of immersion in nature. “The end of autumn and winter, when the aquatic ones acquire decadent tones and capture the light in a dramatic way, are the most poetic moments,” they say in Estudio MIX. “In spring, the volumes of the new shoots break the horizontality of the sheet of water, reflecting endless shades of fresh green. The garden fills with the sounds of birds and the pollinators begin their scouting movement in search of the valuable first flowers of the season. With luck, dragonflies, butterflies, frogs and minnows will end up settling, attracted by a habitat to suit them.
“Bio-pools are healthy: their pure, living water is gentle on the skin and pleasant to the touch,” says André Schäller of the German engineering company Janisch & Schulz. “The presence of animals indicates this purity. Purifying water using gravel and vegetation makes it possible to do without chemicals and electric filters, protecting health and the environment”, he adds.
Although they require a higher initial investment, in the medium term natural pools require less maintenance than conventional ones. “Sustainability is a concept in which different interpretations fit, but what we all agree on is that it is necessary to use water responsibly”, they believe in Estudio MIX. Thanks to the natural regeneration cycle, in a bio-pool that keeps the habitat alive, it will not be necessary to empty and refill, only replace the water that evaporates. The pump to circulate the water can be powered by solar energy. No chlorine or chemicals needed. Nor is it a treatment plant, which means energy savings.
Naturalized pools have pros and cons. Among the cons, we must take into account that it will not be completely transparent water, that algae will appear —it is not a tragedy—, that if the species are not selected properly, mosquitoes may appear, that aquatic perennials must be pruned once a year… In return, ecology and sustainability are favored, maintenance needs are reduced and the aesthetic possibilities of plants are enjoyed. That long-awaited dip in increasingly hot summers in a pool touched by the grace of an enveloping wild nature will be pure therapy. No selfies. Just turn off your phone and dive.
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