Swimming in a natural swimming pool is a harmonious experience, a seamless blending of environments. While you are separated from the plants, you still feel surrounded by them when you swim, which creates a very special kind of mood.
The colour of the flowers from spring throughout the summer and into the autumn, along with the chorus of the birds and the frogs, makes people feel far closer to nature. It provides them with a very special place to be at any time of the day or night, throughout the whole year. It is a natural oasis.
Most pools ponds and lakes are cleaned and purified by the combination of plants and micro organisms including beneficial bacteria. These micro organisms break down organic wastes into substances which plants can use directly as nutrients. These are now being used in hundreds to private and public swimming locations across Europe over the course of some 25 years.
Natural swimming pools are based on ponds and pools that were once found so abundantly in the landscape. The comparison to a landscape pool is deliberate because that is what a natural swimming pool is, a large pond with special provision for people to enjoy the water as well as the various creatures that are attracted to it. The original concept was developed in Austria by a number of people, who were very conscious of the health benefits of bathing in natural waters found at spas and health resorts.
It was not until 1985 that the idea was commercially developed by an Austrian based company, called Biotop, by the founder Peter Petrich, who conceived the idea of a self cleaning biosystem for swimming pools.
Ecological Balance
Natural Swimming pools are a chemical free combination of swimming zone and aquatic plant garden, known as the regeneration zone. Both zones merge together creating an environment that is intertwined and mutually dependant on one another. These ecologically balanced, self cleaning swimming pools combine the natural cleaning properties of plants with filtration and skimming systems so that there is no need for harmful chemicals.
The result is a biologically chemical free clean swimming environment. The water is clear but not sterilised, as in the traditional swimming pool and it is able to sustain the normal range of pond life, microscopic organisms, invertebrates and even frogs and toads. The aquatic flora and fauna are indicators of the state of the environment and at present their loss in the landscape is huge and very worrying.
The swimming zone ranges between 1200 and 2400mm deep and is plant free. It is usually lined with a rubber liner to prevent water leakage and it is separated from the regeneration zone by a barrier wall. This wall prevents invasion of plants and the substrate. It also makes it much easier to service and drain each zone separately. The wall terminates approx 250mm below the surface of the pool in order to allow free transfer of water into each zone.
Within the regeneration zone, the water is cleansed biologically in co-operation with the roots of the aquatic plants and micro organisms. The aquatic plants act as living filters in this zone and provide an important function in the whole system. These plants absorb decomposing materials and bacteria as well as pollutants from the water and convert them into biomass (organic matter produced by plants and other photosynthetic producers) before providing clean water.
Water plants need these nutrients released through the decomposition process for there growth. These nutritional substances, along with Ecoli and other harmful bacteria are then transformed into mineral salts and are either destroyed or become nutritional elements for the plants. Zoo plankton are important for the natural swimming pool as they feed on single celled algae and filter it out of the water. Through this natural self cleaning process the use of harsh chemicals is not required to keep the pool free from algae and there is very little need for maintenance.
Good Housekeeping
The care and upkeep of the pool can easily be undertaken. The use of a vacuum cleaner for the removal of any silt in the bottom of the swimming zone is an easy task. Likewise the removal of any algae in the springtime and this also presents an opportunity for the owner of children especially to see pool life at a much closer range. The removal of died down vegetation in the autumn is no different from other garden work.
The basic construction requires a deep area of at least 1500 to 2200mm with near vertical walls which need to be constructed for the swimming zone and waterproofed by means of a rubber liner with geotextile under liner. The internal walls are constructed from sustainable materials wherever possible such as recycled plastic, stone, timber or geotextile bags. As they will be acting as a retaining structure for the material and plants in the regeneration zone, they should be carefully engineered.
The water is drawn down through the substrate in the regeneration zone and through perforated pipework to the pump. The water is also taken via the surface skimmer to the pump where it is again filtered before going to the bottom of the swimming zone. The regeneration zone must be of the same size as the swimming area and have an average depth of 300mm of substrate, usually graded from 50 to 450mm.
In some pools the plants would surround the swimming zone, giving a soft planted margin to the pool. In small pools it is better to plant on one side only so as to avoid a tight enclosed effect. Where space is at a premium, an alternative is to create a second pool, perhaps uphill and allow water to flow between the bodies of water, probably using a waterfall.
The regeneration zone utilises a coarse inert substrate, such as shingle/gravel and not topsoil or any other growing media as this would bring high levels of nutrients to the water and would counteract the cleaning effects of the plants. By planting the aquatic plants in shingle they must draw their nutrients from the water itself and so clean the pool. Also by cutting and removing the plant mass each autumn, the impurities held in the plants are physically removed from the water, allowing the cycle to begin again in the following spring.
A surface leaf skimmer is also used to help remove floating debris from the water silt, a combination of decaying vegetation, dust and other detritus will always form in any body of water and depending upon the size and location of the pool it can easily be removed by either vacuum or bottom drain system. A drainage ditch is constructed completely around the pool to ensure that no water runoff enters the pool thereby causing any differences in the pH and the water quality.
Natural Process
Existing swimming pools can easily be converted to the natural process providing that there is space for the regeneration zone, either as a separate pool or as a subdivision. The quality of the water is of special significance. The layout of the pool with it's natural regeneration zone promotes the self cleaning forces of the water and the mechanisms provide a long term stable and hygienic quality. The use of chemicals would only lead to the destruction of the biological balance in the water.
The shallow warmer water of the regeneration zone circulates with the cooler deeper water of the swimming zone and increases it's temperature much quicker. Solar methods can be used providing care is exercised and it is not used until the plants have grown to combat the algae. Fish are not allowed in the pool as they cause damage to the water quality and also encourage birds such as herons, as they could also damage the liner. Ducks, geese and other wildfowl, as well as any pets such as dogs and ponies are also discouraged as they can contribute pests and diseases.
Engine Room
The plants are the engine room of the whole natural swimming pool and are vital for the correct biological functioning of the system. In addition they also provide habitats for wildlife both in and out of the water as well as an attractive visual scene. The use of aquatic plants as a water purifier is a crucial element as they clean the water in several ways. Not only do they provide an excellent habitat for zoo plankton which effectively feed on algae, they die down in the autumn and winter and when the vegetation is removed any impurities are also taken away.
They produce oxygen through photosynthesis which is necessary to support all pool life. This assists in keeping the water clear and many plants can have a growth inhibiting effect on the algae. Different kinds of plant groupings occupy pools with any streams and bogs thereby creating a distinct ecological niche for the locality. This local character should if possible be reflected in the overall planting design.
While the technical factors are of the utmost importance there is still the need for consideration of the design principles. The wide range of aquatic plants provides the designer with considerable opportunities for the creation of a wonderful water garden or landscape. The natural swimming pool provides an attractive biosphere for various kinds of animals and is quickly inhabited after it's creation. They stay mostly in the regeneration zone that serves them well with food and shelter.There are many predatory insects that feed on mosquito larvae.
Amphibians use the regeneration zone as a breeding ground too. They appear in early spring to lay there eggs. However people and frogs do not swim side by side as the amphibians migrate before the swimming season commences. With the emphasis today on a more holistic lifestyle that incorporates organic food, alternative medicine, spring drinking water, physical exercise and the like, then it makes sense to swim in natural water.
Chlorine used in conventional pools is a skin irritant and can be associated with rashes like eczema and a number of serious diseases. Chlorine has been documented to aggravate asthma, especially in those children who make frequent use of chlorinated swimming pools.
While no design can surpass the one created by nature, the role of the landscape architect is to design in a harmonious and ecological manner ensuring that the impact on the environment is minimal. It is very important that the positive attitude to natural bathing and swimming as well as the health giving properties of water, sunshine and gentle breezes on the human body should now be widely recognised both by the leisure industry and governments in provision of their facilities.
Do you have a natural swimming pool, does it work for you? email us poolratings@sky.com or add a comment to this post.
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