Knowledge & FAQ

Natural pools belong to the category of “near-natural bathing waters”, in which the purification of the water corresponds to natural processes. While the processes in swimming ponds are based on the biological processes of still water, those in natural pools correspond to the principles of flowing water. 

The aim is to achieve permanently hygienic and clear water. To achieve this, nutrients and bacteria introduced by air and swimming must be removed from the water. The biofilms in the natural pool filters are responsible for hygienic cleaning and the binding of nutrients, so that nothing stands in the way of healthy bathing pleasure. Any use of poisons is 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 filter basin at the edge of the natural pool. The water is first sucked over a special dolomite gravel and then into the Hydrobalance filter using energy-efficient 12-volt pumps located in the filter basin.

This creates optimum conditions for biofilms on the gravel and in the filter, which trigger a biological self-cleaning process. The result is hygienically and visually perfect quality.

YES! Algae are an important component of natural bodies of water and are almost always present. The trick is to build a natural pool and use a filter system in such a way that algae occur in such small quantities that they are not visible. 

Thanks to the Hydrobalance natural pool system and its specially tailored Nutrient management there is no algae in the swimming area and the water is always crystal clear. When operated correctly, hardly any deposits form and there is no growth of filamentous algae. 

The biofilm is an arrangement 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 that optimum conditions for the build-up of biofilm prevail in the filter. It also ensures that the hardness is set correctly. For this 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 are all substances that enter the natural pool via wind, rain and bathing.

The Hydrobalance filter system incl. gravel without filter basin costs approx. € 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. For more information, planning and realisation of your natural pool, please contact a Hydrobalance-Partner:indoor operation. 

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

The design options for a Hydrobalance natural pool are very diverse. A Hydrobalance natural pool can be designed naturally (like a swimming pond), e.g. with a curved bank made of river stones, or architecturally (like a conventional pool). It can also be designed with wood. Whether the pool itself should be made of wood and/or the bank design, many things are possible here too. The shape of the natural pool itself can also vary and is by no means limited to a rectangular pool. Plants should also be avoided on natural banks, as they are unlikely to 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 on the edge outside the water. 

On our project page numerous different design options can be seen. 

No, there is no minimum size for Hydrobalance natural pools. This is one of the many advantages of our filter system. Due to the small size of the filter zone (from 2.4 x 1.5 metres), even the smallest garden can have a Hydrobalance natural pool. 

The filter zone can remain open or be built over. 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 no upper limit in terms of size.

Yes, in most cases this is even possible without major conversion work. We will inform you about the details or a Hydrobalance partner company in your neighbourhood. 

Yes, in principle this is possible. It is important that the planting zones of the swimming pond are separated from the natural pool. We will be happy to provide information on the details or Hydrobalance partner in your neighbourhood.  

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 this does not determine the two most important water values for the satisfactory operation of a natural pool accurately enough.  

The two important water values for the 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 the option of filling water treatment. 

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

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

Plants are only possible to a limited extent in the natural pool. As 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. 

Unlike a swimming pond, plants are not necessary for a natural pool to function properly. 

If plants are desired for visual reasons, there is the option of a combination 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 is permitted. We recommend heating using panel heating (underfloor heating) and an air heat pump.

The specific materials vary depending on the project. Materials that are required particularly often include the following:

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

Nutrient inputs are technically understood to be the introduction of organic and mineral substances into the water. In natural pools, this mainly occurs via bathing, 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 is designed accordingly. Excessive inputs are, for example, a large party, a severe storm or incorrect fertilisation of the garden.  

The amount of care required depends on your individual requirements. 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. It's exactly the same with nature (pools).

Basically, the more individual the design (possibly natural bank shape, different depths, benches, steps, ...) and the higher your visual requirements, the higher the maintenance effort. (This is easily comparable with gardening. Here, too, you need to mow, fertilise and maintain). As a rough guide, it can be said that it makes sense to use the pool robot 1-2 times a week for architecturally designed natural pools. 

It is important to „harvest“ the biofilter once a year to ensure safety at the entrance and in the non-swimmer area. When planning, reference can be made here to automatic cleaning using a pool robot. The cleaning interval for the swimming area and pool walls is therefore customised. 

Hydrobalance nutrient management has a significant influence on the visual quality and further reduces the maintenance effort. In order to handle this easily and optimally, we offer suitable Care Products .

In natural pools, as in all other natural bodies of water, so-called biofilms form on all surfaces. Just like the biofilm in the filter, these deposits help to clean the natural pool. They are hygienically completely harmless and not harmful to health.  

For safety reasons, these slippery surfaces must be removed regularly in the entrance area and in the non-swimmer area.  

We differentiate between water cleaning, pool cleaning and filter cleaning. Water cleaning and pool cleaning are ongoing maintenance tasks, while Hydrobalance only requires filter cleaning once a year at the end of the bathing season.

 

WATER CLEANING

• Ongoing maintenance automatically handled by the Hydrobalance filtration system

• Important: Support from the Hydrobalance nutrient management 

 

POOL CLEANING

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

• It makes sense to consider the cleaning options at the planning stage

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

• In addition to natural pool robots, there are special accessories for the mechanical cleaning of surfaces such as manual or mechanical brushes as well as high-pressure cleaners 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. This means that the filter only needs to be cleaned 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:indoor operation.

 

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

The pump operation for this size amounts to approx. 800 kW/year for standstill in winter or 1300 kW for continuous operation. 

Natural pool robots are available in different price ranges depending on the equipment, from around € 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 must be agreed with the respective Hydrobalance-Partner:indoor operation company. 

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

Covers are useful for heated natural pools or if large amounts of water are expected from outside, e.g. near a forest. We recommend “floating” covers, i.e. those that do not float on the surface of the water. This allows sufficient gas exchange in the water and prevents the formation of deposits on the cover. 

As water is a living system, excessive nutrient inputs can lead to the short-term formation of green or brown deposits on the surfaces. In rare cases, a particularly large excess of nutrients can lead to the temporary formation of filamentous algae. With Hydrobalance, turbidity only occurs due to the introduction of biologically inhibiting substances.  

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

No. It is not necessary to drain or change the water for many years.

Refilling takes place, for example, when it is hot and dry and evaporation is higher than precipitation.

Even with the annual biofilm harvest, around 10 cm of water is lost, which then needs to be replenished. 

LOW MAINTENANCE REQUIREMENTS

• The Hydrobalance system is designed to make your bathing water easy to maintain. Maintenance work is reduced to a minimum, while the design and choice of materials make ongoing cleaning much easier. 

 

FAMILY MEETING PLACE

• Public natural pools attract families. Swimming ponds and natural pools also increase the number of visitors from family and friends in the private sphere, especially during the bathing season, and are therefore also important social elements. 

 

TEMPERATURE REGULATION

• Water in the garden creates a microclimate that balances out strong temperature fluctuations. In combination with the surrounding design, this creates a climate-friendly habitat for humans 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 systems 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. Swimming ponds and natural pools, like natural bodies of water, have a pH value of 8.3-8.4, a value to which our organism has adapted over thousands of years. This means there is no dry skin, straw-like hair or reddened eyes after a bath. 

 

USE ALL YEAR ROUND

• While chemically treated pools with a lowered water level are not an ornamental feature outside the bathing season, naturally treated bathing waters remain filled at all times and are therefore an attractive centrepiece all year round. 

 

WATER SAVING

• After filling once, only any evaporation needs to be equalised. Due to the possible water fluctuations of up to 20 cm, even this measure is rarely necessary. The rinsing water from the biofilm harvesting system is ideal as irrigation water for the garden and is therefore not lost. 

 

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. 

 

INCREASING BIODIVERSITY

• Natural water in the garden is an important resource for a variety of living creatures. In addition to providing a habitat for various amphibians, it also creates a drinking water reservoir for insects, birds and small mammals. The diversity of species increases and thus acts against pests and diseases on plants.

 

ENERGY BOOST

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

 

WATER RESERVOIR

• The discussion about water shortages in large areas of Europe has led to uncertainty among many people. 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 a „counterpart“, whether animal or plant, is an enrichment.