The swimming zone is the area intended for swimming that resembles a conventional swimming pool or pond.
The regeneration zone consists of a lined overflow pool filled with specific filtration substrate and flora. Plants used for water regeneration can be supplemented with decorative flowering species to create an attractive water garden environment. The biological processes that clean the water take place in this zone.
The swimming zone should be physically separated from the regeneration and should reach a depth of 2 m (6 ft 6 in) in swimming ponds. The regeneration zone and swimming zone must be equal in area for sufficient purification. The swimming portion of the pool can look like a conventional swimming pool or a natural pond. The regeneration zone can be placed adjacent to the swimming area or in a remote location depending on the space available. In modern natural swimming pools there is no minimum depth for the swimming zone and the regeneration zone can now be reduced greatly and in some cases is non existent. Clear Water Revival was the first company to build indoor natural swimming pools in the UK. In these pools a regeneration zone can be used outside the building or a natural filtration chamber can be built without a planted area indoors.
In an NSP, swimming pool water flows via gravity from the swimming pool into distribution shafts. The water then passes through a biological fine filter/bioreactor before it is pumped into the regeneration zone. Plants in the regeneration zone are planted in the substrate, and these plants compete for nutrients that would feed algae. The water is cleaned biologically by the metabolic processes found in the substrate in which the plants are rooted. Thus, microorganisms and the water plants ensure effective, continuous cleaning. No processes beyond these, such as UV sterilization, are found in true European style NSPs.
Because of their reliance on natural environmental factors, each NSP system is built with consideration to the region and climate where it is installed. Construction elements such as the biological filter and the combination of contaminant ridding plants vary with each pooWhile the most common method of building Natural Swimming Pools is by using a regeneration zone, advances in NSP technology have all but made this method obsolete. Using a regeneration zone strictly limits where building an NSP is plausible. In the new Pools by Nature US Bio filtration method water flows from the pool, usually by gravity, through a series of filter systems without the need for any regeneration plant area. Skimmers are not required and after the initial stage, an automatic screen filter cleans the remaining debris particles, down to a particle size of 70 microns. At that time, water move through a Biofermenta filter system, where it is biologically purified and oxygen is added to the water. Pure water can then returned to the pool through low-wattage water pumps, dispersed from bottom outlets that drive the water up to the surface, and provide more of the needed water oxidation. This method works very well in warmer climate, can build indoor bio pools and achieves excellent performances in water clarity and health.
Other option is using formulas developed by Total Habitat for a built in biological filtration system, an NSP without a regeneration zone can handle any climate. Using this built in filtration "reveals crystal-clear water and thriving populations of beneficial bacteria that strip the water of nitrites, nitrates, E.coli, planktonic algae, skin and body oils, fish food and fish waste".[7] This method is extremely advantageous for a number of reasons. Fish thrive in the water (with a regeneration zone, fish are not allowed in the water), the water may be heated (while NSPs with regeneration zones may be heated, using built in biological media allows for a Natural Swimming Hot Tub). Additionally, with a regeneration zone, the pool needs to be "winterized". A Natural Swimming Pool with built-in biological media may be used year-round.
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