How does a Natural Pool „work“?

Due to the natural design, the biological self-cleansing forces of the Natural Pool are extremely effective. Impurities are absorbed by the plants as nutrients and harmful bacteria are destroyed by natural water organisms. Thanks to the biological self-cleansing properties absolutely no chemicals are required. Technology is used to support and enhance the natural processes. Biotop has always attached a great deal of importance to designing technical components that are simple and easy for the user to understand.

In the planning of Natural Pools, generally the ratio of the swimming zone to the regeneration zone is 1:1 and the depth is at least two meters in the swimming area. This is the basis for a functioning pool. If more technology is use, the regeneration area can be smaller with less depth.


A Natural Pool will function as it should if the regeneration area is designed correctly and the underwater plants are used properly. The pool is fortified with zooplankton (water fleas, rotifers, paramecia), which play an important role in keeping the water clean on a continual basis. All it takes is a little bit of patience until the pool finds its natural balance. A Biotop Natural Pool functions in perfect balance starting from a water surface area of 30 to 40 m2. And in terms of size, the sky’s the limit.

Technical components

1 Submersible Pump Chamber

BIOTOP has developed a special water circulation concept for its Natural Pools. The pump is completely submersed in water in a chamber, allowing water to flow to it simply by the force of gravity instead of being “sucked in” by the pump. Mounted at the bottom of the chamber, the pump conveys the water back into the pool through pressure pipes.


  • Submersed pumps are very quiet, making almost no noise
  • Due to the low noise level, the chamber can be installed underneath the wooden deck
  • The pump does not need to be uninstalled for winter
  • The pipes do not need to be emptied for winter
  • Incoming and outgoing pipes can be regulated individually
  • The submersed pump is optimally cooled by the water

Information Sheet

2 Curved Screen Skimmer

The purpose of the curved screen skimmer is to remove floating particles from the Natural Pool. The water flows over a curved screen with a mesh width of only 0.3 millimetres that removes even the smallest contaminants. A sophisticated mechanism controls the water flow via a flexible flap so that the correct amount of water always flows over the screen. BIOTOP was granted a European patent for this development.


  • Even the finest floating particles are eliminated from the system
  • Nutrients are removed from the water
  • The screen is self-cleaning and therefore cannot become clogged

Information Sheet

3 Carbonator

The Carbonator provides the water plants with carbon dioxide in a natural manner, thereby regulating the pH value of the water. This unique process was developed and patented by BIOTOP.

4 Angle elements

Angle elements assembled in a modular construction system separate the swimming area from the regeneration zone. This saves time and reduces costs. The elements consist of polyethylene plastic and are UV-resistant; they are made from recycled material and are themselves recyclable.

5 Biological Compact Filter

Water flows through the filter vertically from top to bottom and is biologically cleaned along the way, i.e. impurities causing turbidity and organic compounds are broken down by bacteria. The result is crystal-clear water. To optimize the cleaning performance of the bacteria, water flows through the biofilter permanently. The biologically cleaned water then continues into the PhosTec Upstream filter.


  • Biological cleaning without the need for chemicals
  • Requires no electrical power
  • The bio compact filter is comparatively small in size and installed under the deck, invisible to the user

Information Sheet

6 The Phosphorus Filter “PhosTec UPSTREAM“

The PhosTec Upstream phosphate filter is an optional addition to a Natural Pool. It binds the phosphorus dissolved in water, thus preventing the growth of algae efficiently and without the use of chemicals. In this way, the algae are effectively “starved”. The water flows through the filter from bottom to top to minimize the risk of clogging the filter, and the nutrient-poor water is then pumped back into the pool by a small pump. Biotop was granted a European patent for the combination of the biofilter and PhosTec Upstream filter.


  • Phosphorus is removed from the water efficiently and reliably
  • Small size saves space
  • Easy handling
  • Simple replacement of the filter material
  • Long life span

Information Sheet


The components 1, 5 and 6 can be united within a single unit, the “Combi-Box”, to save space.

Construction Methods

Select the construction method that you like the best. All three can be combined with one another.

Corner Element Construction by Biotop

Corner Element Construction

With this modular building method, the divider between the swimming area and regeneration zone is created using angle elements. The elements are recyclable and thus environment-friendly, and their variable connection system allows the swimming area to be shaped as desired. The pre-fab elements used in this system save time and provide great flexibility in terms of design.

Concrete or Cinderblock Walls by Biotop

Concrete or Cinderblock Walls

The wall construction method is a high-stability technique that makes the greatest possible amount of space available for the swimming area. The smoothly and precisely applied liner also provides the possibility of using a pool robot for automatic cleaning. Separate emptying of the swimming area and regeneration zone is also possible with this construction method.

Earth-Wall Construction by Biotop

Earth-Wall Construction

In this comparatively inexpensive variant, which is also flexible in terms of shape, the swimming area is separated from the regeneration zone by a simple earthen embankment. The wide dam-like shape requires more space as well as a stable natural foundation.


  • Pre-fabricated components
  • Quick and easy construction
  • Attractive design
  • Swimming area can be shaped as desired
  • Wooden cover provides seating


  • Precise geometric shapes
  • Vertical walls from top to bottom in the swimming area
  • Higher investment in materials and costs
  • DIY construction is possible


  • Gently sloping shape of the swimming area
  • Economically priced
  • Larger surface area needed due to greater width of earth wall

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