Knowledge & FAQ

Natural pools are part of "bathing waters which are close to nature". This means that water purification mimics natural processes. While swimming ponds follow the biological processes of still waters, natural pools adhere to the principles of flowing waters. 

Because of wind or pool usage nutrients and bacteria can find itself in the water. To achieve perfect hygenic and clear water permanently these nutrients and bacteria must be removed. The biofilms in natural pool filters are responsible for hygienic cleaning and nutrient binding, ensuring a healthy swimming experience. The use of chemicals is strictly prohibited. 

The Hydrobalance filtration system, developed in 1997, operates on the principle of mechanical-biological water purification.

The Hydrobalance filter is installed in a separate filtration basin at the edge of the natural pool. Energy-efficient 12-volt pumps, located in the filtration basin, first draw the water through a special dolomite gravel and then into the Hydrobalance filter.

This process creates optimal conditions for biofilms on the gravel and in the filter, initiating a biological self-cleaning process. The result is water that is both hygienically and visually flawless.

Yes! Algae are essential in natural waters and are almost always present. The key is to design a natural pool and use a filtration system in a way that algae are kept in low quantities so that they are not visually noticeable. 

Thanks to the Hydrobalance natural pool system and its specially tailored nutrient management there are no algae in the swimming area, and the water remains crystal clear. When properly maintained, there is minimal buildup of plaque , and no growth of filamentous algae. 

A biofilm consists of mostly decomposing organisms (destruents) that cover themselves in a slime layer of polysaccharides and live together symbiotically. The biofilm is what makes stones slippery in natural water, for example.

Nutrient management means ensuring optimum conditions in the filter for the build-up of biofilm. It also ensures that the water hardness is set correctly. For this purpose, we offer our Hydrobalance Care Products .

A skimmer flap is a flexible weir that adjusts to the water level.

In the context of natural pools, "inputs" refers to all substances that enter the pool via wind, rain, and swimming.

The Hydrobalance filtration system, including gravel without the filtration basin, costs approximately € 14.000 (gross) for a natural pool with a size of up to 35 m². 

The total cost of a natural pool depends very much on the design, choice of materials and other individual factors. Please contact a Hydrobalance partner for more information, planning and realisation of your natural pool. Hydrobalance-Partner:innenbetrieb. 

Trees and shrubs are important design elements in gardens and are of course also present on neighbouring properties. Normally, the filteration system is calculated in a way that the input from flowers, pollen or leaves can be processed. Skimmers provide additional support for this. However, a few plants, such as walnut trees, can cause a slight inhibition of the biology. Branches of fruit trees which protrude above the water usually have to be removed to prevent fruit from falling into the pool.

The scope for designing a Hydrobalance natural pool is very diverse. A Hydrobalance natural pool can be designed to look natural, reminding visually of a swimming pond (e.g. with a curved shore made out of river stones) or architecturally (like a conventional pool). Moreover, wooden designs are possible too. Whether the pool itself is made of wood or just the shore design, various options are available. The shape of the natural pool itself is also flexible and is by no means limited to a rectangular shape. Plants should also be avoided on natural shores, as they hardly thrive in a natural pool due to the low nutrient supply. To bring vitality around the water, regardless of the design of the natural pool, we recommend lush perennial planting along the edges outside the water. 

On our project page you can explore a variety of design options. 

No, there is no minimum size for Hydrobalance natural pools. This is one of the many advantages of our filteration system. Even the smallest garden can accommodate a Hydrobalance natural pool due to the small size of the filter zone, which starts at just 2.4 x 1.5m. 

The filter zone can either remain open or be covered. If the filter zone is built over, it can also be used as a terrace area.  

The size of the natural pool therefore depends on the utilisation requirements and the available space. 

Thanks to the modular Hydrobalance filter system there is also no upper size limit.

Yes! In most cases, this is possible without significant renovation work. We or a Hydrobalance partner in your area will be happy to provide you with more details. 

Yes, in general this is possible. It is important that the planting zones of the swimming pond are separated from the natural pool. We or a Hydrobalance partner in your area will be happy to provide you with more details.  

Before filling a natural pool, the filling water must always be analysed in order to avoid any unpleasant effects during commissioning. A drinking water analysis is not sufficient, as it does not accurately determine the two most important water values for the satisfactory operation of a natural pool.  

The two important water values for a natural pool are the phosphorus value with a maximum value of 10 µg/l and the sulphate value. If the two values are too high, there is a possibility of treating the filling water. 

Well water can also be used after it has been analysed and, if necessary, suitably treated. 

The use of rainwater is completely excluded, as many heavy metals accumulate in rainwater due to run-off over roof surfaces. 

Plants in a natural pool are only possible to a limited extent. As the standards prohibit the use of substrates, the plants are dependent on the nutrient supply from the water. With the Hydrobalance system, the nutrient content in the water is kept so low that plants cannot survive. 

In contrast to swimming ponds, plants are not necessary for the natural pool to function. 

If plants are desired for aesthetic reasons, there is the option of a combined natural pool. 

No, fish are not allowed in a natural pool. 

Yes, a natural pool can be heated. According to ÖNORM L1128, a maximum temperature of 36 degrees Celsius is allowed. We recommend heating it using an underfloor heating system and an air heat pump.

The specific materials vary depending on the project. However, the following materials are often needed:

• Suitable waterproofing
• Usually a liner
• PVC pipes and connecting parts
• Hydrobalance filtration system
• Preferably dolomite gravel
• Stainless steel
• Ladder or a handrail for steps

In technical terms, nutrient inputs refer to the introduction of organic and mineral substances into the water. In natural pools, this mainly occurs through bathing activities, leaves, and pollen. The refill water is also a decisive factor. 

An average nutrient input is measured for each natural pool and the filter system will be designed accordingly. Excessive inputs are, for example, a large party, a heavy storm or incorrect fertilization of the garden.  

The time and effort required for maintenance depends on your individual preferences. This is also comparable to house cleaning and garden maintenance. Some people look after their house and garden every day in order to enjoy maximum cleanliness at all times. Others are satisfied with average hygiene and tidiness and devote less time to these activities. The same applies to natural pools.

Generally, the more customised the design (e.g., natural shoreline, varying depths, seating benches, stair designs, etc.) and the higher your aesthetic standards, the more maintenance is required. (This is comparable with gardening. Here, too, you need to mow, fertilise and maintain.) As a rough guideline, it is advisable to use a pool robot 1-2 times per week for architecturally designed natural pools. 

It is important to "harvest" the biofilter once a year to ensure safety in the entry and in the non-swimmer area. When planning, you can consider an automatic cleaning system using a pool robot. The cleaning interval for the swimming area and pool walls is thus individual. 

Our Hydrobalance nutrient management has a significant influence on the visual quality and further reduces the maintenance effort. To handle this as easy and optimal as possible we offer suitable Care Products .

In a natural pool, so-called biofilms form on all surfaces, just as they do in all other natural waters. These films, like the biofilm in the filter, help to clean the natural pool. They are hygienically completely harmless and pose no health risks.  

For safety reasons, slippery layers must be removed regularly from the entrance area and the non-swimmer area.  

We differentiate between water cleaning, pool cleaning and filter cleaning. Water cleaning and pool cleaning are ongoing maintenance, with the Hydrobalance system, filter cleaning is only necessary once a year, at the end of the bathing season.

 

WATER CLEANING

• Ongoing maintenance automatically handled by the Hydrobalance filtration system

• Important: Supported by Hydrobalance nutrient management 

 

POOL CLEANING

• Ongoing maintenance depends on the shape, depth, and choice of material of the natural pool

• It is advisable to consider cleaning options at the planning stage.

• Usually, the ongoing cleaning of most surfaces is carried out by natural pool robots

• In addition to natural pool robots, there are special tools for mechanical surface cleaning such as manual or mechanical brushes, pressure washers, and cleaning agents.

 

FILTER CLEANING

• Only necessary once a year at the end of the bathing season

• Also known as filter harvest or biofilm harvest

• Hydrobalance calculates the required filter capacity for an entire season at the planning stage. Thus, filter cleaning is only necessary once a year at the end of the bathing season.

 

For detailed advice and an introductory training on cleaning and maintenance, please reach out to your Hydrobalance-Partner:innenbetrieb.

 

The costs for nutrient management depend on the water volume and the water values and amount to approximately € 150 to € 300 per year for a 50 m³ pool.  

The pump operation for this size amounts to approximately 800 kW/year when not in use in winter or 1300 kW/year for continuous operation. 

Natural pool robots are available in various price categories depending on the features, from approximately € 2,000 to € 4,000. 

Of course, it is also possible to have the natural pool maintenance carried out by the natural pool builder via a service contract. This should be discussed with the respective Hydrobalance-Partner:innenbetrieb company. 

A natural pool can, but does not have to be covered. 

Covers make sense for heated natural pools or if large amounts of nutrient inputs are expected from surroundings, e.g. if there is a forest nearby. We recommend "floating" covers, meaning those not directly on the water's surface. This allows for sufficient gas exchange in the water and prevents the formation of plaque on the cover. 

As water is a living system, excessive nutrient inputs can lead to the short-term formation of green or brown layers on the surface. In rare cases, a particularly large nutrient surplus can lead to the temporary growth of filamentous algae. With Hydrobalance, turbidity only occurs when substances that inhibit biological processes are introduced.  

In such cases, please contact Hydrobalance or your Hydrobalance partner company, as we can offer targeted solutions for any imbalances. 

No. Draining or changing the water is not necessary for many years.

The water should be topped up, for example, during hot and dry periods when evaporation exceeds precipitation.

Besides, during the annual biofilm harvest, around 10 cm of water is lost, which then needs to be topped up. 

LOW MAINTENANCE REQUIREMENTS

• Hydrobalance offers easy-care natural pools. Maintenance work is reduced to a minimum, and ongoing cleaning is significantly simplified through the design and choice of materials. 

 

FAMILY MEETING PLACE

• Public natural pools attract families. Private swimming ponds and natural pools increase the frequency of visits from family members and friends, especially during the bathing season, making them socially important elements. 

 

TEMPERATURE REGULATION

• Water in the garden creates a microclimate that helps to balance out extreme temperature fluctuations. In combination with the surrounding design, this creates a climate-friendly habitat for people and animals.

 

ENERGY EFFICIENCY

• The Hydrobalance system uses energy-efficient 12 volt pumps. For example, pumps with a total power requirement of 155 W/h are used for pools up to 35 m². The system can be switched off during the winter months. 

HEALTHY BATHING WITHOUT DISINFECTION

• As chlorine is only effective at pH values below 7.5, the pH value in chemically treated pools must be kept in the acidic range. Like natural waters, swimming ponds and natural pools have a pH value of 8.3-8.4, a value to which our organism has adapted over thousands of years. As a result there is no dry skin, straw-like hair or red eyes after a swim. 

 

YEAR-ROUND USE

• While chemically treated pools often lose their aesthetic appeal outside the swimming season due to lowered water levels, naturally maintained swimming areas remain filled and continue to serve as attractive focal points all year round. 

 

WATER SAVING

• After the initial filling, only evaporation needs to be replenished. Due to the possible water fluctuations of up to 20 cm, even this measure is rarely necessary. The rinsing water from the biofilm harvest is ideal as irrigation water for the garden and is therefore not wasted. 

 

ECOLOGICAL

• Hydrobalance offers an honest system. We create optimal conditions for the desired biology and thus create crystal-clear water without toxins and without additional nutrient binders such as iron filters. 

 

INCREASED BIODIVERSITY

• Natural water in the garden is an important resource for a variety of living organisms. It provides a habitat for amphibians and also creates a drinking water reservoir for insects, birds and small mammals. The increase in biodiversity and acts against pests and diseases on plants.

 

ENERGY BOOST

• Living water creates an energy balance in the human body. Stressed individuals calm down, tired people are energised and revitalised. Water has always had a unique attraction for people. Living near water has a number of positive effects and promotes general well-being. 

 

WATER RESERVOIR

• Concerns about water scarcity in large parts of Europe have left many people uncertain. Swimming ponds and natural pools are large, non-toxic water reservoirs for drinking water that can bridge long periods of drought. 

 

ENVIRONMENTAL AWARENESS

• In near-natural bathing waters, we learn that habitats can be shared and that the presence of other organisms, whether animal or plant, is an enrichment.