How to make eco-friendly swimming pools: Complete construction guide

Natural pools are an ecological and different alternative to relax in a natural space at home.

Their construction is as complex as the construction of a swimming pool, but with the right guidance we can have our own natural pool.

The selection of the right place, the choice of materials and the design are some of the keys to achieve a perfect natural pool at home and in this article we will see how to deal with these elements.

What are natural swimming pools?

Natural pools are water spaces that are constructed without the use of chemicals, using the principles of ecology to purify the water.

Some of the most well-known main features are:

• Natural pools are divided into two main areas: the bathing area and the water regeneration area.
  • The bathing area is where bathers enjoy the water. In this area, the water is in constant movement thanks to a biological filtering system.
  • The regeneration zone is where the biological filtering system is located, which purifies the water naturally, using aquatic plants and micro-organisms that feed on the waste present in the water.

• To build a natural swimming pool, it is necessary to choose the right site, carry out an excavation and build the basin, the liner and the filtering system.
• In the regeneration area, it is important to choose the right plants, those that are capable of absorbing the nutrients and waste present in the water.
• The maintenance of a natural pool is essential to keep the water crystal clear and free of algae. This maintenance includes cleaning the filtering system, pruning the aquatic plants and checking the water chemistry.

Advantages and disadvantages of having a natural pool at home

Before deciding to build a natural pool at home, it is important to know the advantages and disadvantages of this particular option:

Drawbacks: However, there are also some drawbacks to consider when deciding to build a natural swimming pool at home.

For starters, the construction is more difficult and costly than a conventional pool, as it requires land preparation and the use of specific materials such as gravel, sand and volcanic stones.

In addition, it can be more difficult to maintain the right temperature in the pool, as it is important that the sun does not heat the water as much as in a conventional pool.

Design of our natural pool

Designing a natural pool is a complex process that requires careful planning and specialist knowledge.

The natural pool is usually divided into two areas: a bathing area and a water regeneration area, specially designed for the plants and flora that keep the water clean.

The following are the most important aspects to consider when designing a natural pool.

Choosing the right location

Choosing the right location for a natural pool is essential to ensure its success. The chosen site should have sufficient space for the size and shape of the pool and should be away from trees and other potential sources of dirt.

It is also important to consider the sun exposure and shade you want to have in the pool area.

Excavation and construction of the pool

The excavation and construction of the pool shell is an important process that should be carried out by an experienced professional.

It is essential to ensure that the pool is the right shape for proper water circulation, as well as having a uniform depth to facilitate the growth of aquatic plants.

The inclusion of a staircase area is also important to facilitate access to the pool.

Nuestra recomendacióm siempre es gunitar la piscina, para garantizar la estanqueidad del vaso y una mayor durabilidad.

Pool lining and filtering system

The pool liner is an essential part of the construction of a natural pool.

Different materials can be used such as gresite, porcelain stone, gravel, sand and even clay, depending on the aesthetics you want to give it, but it is important to choose one that does not contribute nutrients to the water and depending on the finish you want for the walls.

In this video Jordi explains the different finishes available to make your natural swimming pool.

The filtration system

In addition, it is important to install a natural filtration system to keep the water clean without the use of chemicals.

Filtering systems can include the use of biological filters, such as a trickling filter or a moving stone bed filter, or a closed circuit that allows the water to circulate constantly.

Depending on the water and what we are looking for, we can opt for one or more. If you want to learn more about biological filters , have a look here.

Types of natural pools according to their construction

There are different types of natural pools depending on their construction.

In this section, we will focus on gunite concrete pools and those made of fibreglass, polypropylene, among other materials.

Gunite concrete pools

Gunite concrete pools are the most common in the construction of natural pools. It is a reinforced concrete structure reinforced with steel mesh and sprayed in the form of gunite. Its resistance and durability are outstanding, as well as being customisable both in shape and size.

As for the construction of a gunite concrete pool, it starts with the excavation of the land to give the desired shape for the pool, then iron reinforcing mesh is placed and once the structure is ready, the gunite is sprayed.

Once the gunite has hardened, the structure is covered with a coating to make it waterproof and then covered with a layer of sand and gravel.

Swimming pools made of fibreglass, polypropylene, etc.

Another type of natural pools are those made of fibreglass, which are prefabricated in factories and assembled in the place where the pool is to be located.

These pools are characterised by being less resistant than those made of gunite concrete, but on the other hand, their installation is quicker and simpler. There are also polypropylene pools that are light and resistant, and they also have the advantage of being resistant to the sun’s rays and chemical products.

The main advantage of fibreglass and polypropylene pools, among other materials, is their ease of installation.

They are quicker to build as they are prefabricated pools, which also results in lower costs. However, they must be chosen carefully as, once installed, no changes can be made to the design.

It is very common for this type of pool to be treated against algae. In this case this treatment is not recommended for a natural pool.

Liner: EPDM or TPO is recommended.

PVC is not recommended because in addition to having less durability, in most cases it has finishing products that are incompatible with plants that can be released into the water.

There are special PVCs on the market that are used in food tanks or special for natural areas.

Other finishes for natural pools

• Paint: this is less recommended because it is less durable, but if this finish is chosen it must be a polyurethane, polyurea or epoxy based paint. Acrylic or chlorinated rubber paints should not be used.
• Natural stone: If this material is chosen, it is important to check that it does not add phosphates to the water.
• Microcement: it is valid, although it is not usually used because it is expensive.
• Lime mortar finish: this is valid, except when the pH of the filling water is very acidic.
• Sand finish: We do not recommend installing this material because it is very rough. As it accumulates a lot of verdigris, the pool will look green from the outside.

Zones of our natural pool

The natural pool is divided into two clearly defined zones: the bathing zone and the regeneration zone. Each of them has a different function and it is important to know them in order to achieve a healthy and balanced natural pool.

• Swimming zone. This is the volume of water in which swimming is practised, so that the depth, shape, size and layout of the accesses will vary according to the project variables.
• Regeneration zone. This is the space in which plants grow. In a natural swimming pool it can represent from one sixth to half of the total surface.
  

• Biological filter. It can be from a gravel surface integrated with the plants (biological filter + regeneration zone) to a small drum filter of reduced dimensions.
• Other filtering zones. The natural pool may also need technical spaces for electrical panels, pumps or other additional filters.
  

These zones can be integrated in the same pool or separate, establishing different relationships between them and with the environment.

This has an impact on both the design of the pool and the design and sizing of the purification installation, and will depend on several variables, such as the personal preferences of the users, the use to which the pool will be put, the space available or the economic resources.

Bathing area

This is the main area of our natural pool, where we swim and enjoy the water. It must have an appropriate size for the number of people who are going to use it and a design that adapts to our needs.

It is recommended that this area has a minimum depth of 1.50 metres and a maximum depth of 2.50 metres. It is important to keep the pool water at a lower temperature than usual, so the deeper the pool, the lower the water temperature.

On the other hand, it is important to choose the finishing materials that will be used to cover the natural pool.

Always remember that depending on the finish, the verdigris, which is inevitable in this type of pool, will be easier or more difficult to remove (depending on the porosity of the finish).

Plant area and water regeneration

This is the area where the water in the natural pool is regenerated by the natural filtration carried out by the plants and natural flora.

In this zone, aquatic plants are placed to help maintain the biological balance and oxygenate the water.

It is important to choose correctly the aquatic plants to be used in our natural pool.

Some of the most commonly used plants are: water lilies, water spades, reeds, water nasturtiums, among others.

What we always encourage is the use of native plants.

In addition, it is important to research the needs of each plant in terms of light, temperature and pH to be able to place them in the most suitable place in our natural pool.

It is important to take care of the plant and water regeneration area and to carry out the corresponding maintenance work. It is important to prune the plants so that they do not grow too much and hinder the circulation of the water. It is also important to remove dead leaves and organic debris that may accumulate in this area to prevent the proliferation of bacteria and unicellular algae.

On the other hand, we use marsh plants as a support, basing the operation of the pool on submerged plants that have much more oxygenation and filtration capacity.

Operation and maintenance of our natural swimming pool

Once our natural pool has been built, it is important to ensure its correct operation and maintenance to guarantee the health of the water and the bathers. The following are the main areas to check:

Water circulation and biological filtration system.

In a natural pool, biological filtration is the key to keeping the water clean and clear without the need for chemicals.

This can be achieved by different types of biological filtration systems such as the moving bed filter, the trickling filter or the filter with regeneration plants.

Biological filters work through a series of biological and chemical processes that remove impurities from the water. It is important to regularly check the pH levels of the water and to clean the biological filter properly to maintain a good filtration system.

What is the pH of water?

The pH is the measure of the acidity or alkalinity of the water. The ideal pH for a natural pool should be between 8.0 and 8.6.

How often should the biological filter be cleaned?

The biological filter should be cleaned approximately every six months. However, it is important to be aware of changes in water clarity and adjust the cleaning frequency accordingly.

Water maintenance and combating single-celled algae

Single-celled algae is one of the biggest challenges in maintaining a natural pool. These algae usually grow in stagnant water, so it is important to ensure good water circulation. In addition, it is recommended to use natural products such as barley or spirulina, which help to prevent algae growth.

If algae do appear, it is not advisable to use a brush to remove them manually, as this will only spread them into the water. The ecosystem must be able to rebalance itself.

How to prevent algae proliferation?

• Ensure good water circulation.
• Maintain proper pH levels.
• Check phosphorus levels in the water.
  

How to eliminate algae?

If algae appear, it means that the ecosystem is not balanced correctly or has become unbalanced, so check the steps that have been taken and make sure that everything is still in order. If everything is correct, the pool should return to its transparent and clean state on its own.

Chemicals and cleaning of the biological filter

In natural pools, no chemicals are used to maintain the water quality. However, it is important to clean the biological filter regularly (when it is more than 50 cm thick) to ensure that it works properly and that the natural pool remains healthy.

What chemicals are recommended for cleaning a natural pool?

There are some natural chemical products that help to keep the water of a natural pool healthy.

This is the case of hydrogen peroxide, sodium chloride or sodium orthophosphate, which can be used to control the growth of algae and bacteria. In any case, it is recommended to use them in low doses and avoid using conventional chemicals.

Keeping a natural pool in perfect condition is easier than it might initially appear. With good water circulation, an effective biological filtration system and the right use of natural products, you can not only enjoy a refreshing swim but also a natural oasis at home.

Final touches and fine-tuning of our natural swimming pool

Once our natural swimming pool has been built, it is time to put the finishing touches and make the final touches before enjoying swimming in it. In this section, we detail the steps to follow to finish the creation of our natural swimming pool.

Check that the pool is watertight

The first thing to do is to make sure that the pool is completely watertight. To do this, fill the pool with water and let it stand for 24 hours. If the water level does not drop during this period, we can consider the pool to be completely watertight. If not, we will have to look for possible leakage points and repair them before continuing with the process.

Carrying out pH adjustments

The pH of the pool water should be close to 8.5 for the water to be balanced and correctly treated, one point higher than in a chlorinated pool.

If the pH is too low or too high, it should be adjusted using special natural products designed for this purpose. In this type of pool it is not as important to measure the pH regularly as in chlorinated pools during the summer, so only in the event of turbidity or algae growth should this point be checked.

Water quality parameters in a swimming pool.

In Spain, the criteria for a conventional pool are set out in Royal Decree 742/2013, we will take these values as good values when establishing a reference for water quality, although each country will have different criteria:

Chemical-physical parameters:

• Ph limit between 6.0 and 9.0.
• Transparency. Bottom outflow visibility criterion.
• REDOX potential between 250 and 900mV.
• Turbidity lower than 5 UNF

Microbiological parameters:

• ‘Escherichia coli’ 0 CFU
• ‘Pseudomonas aeroginosa’ 0 CFU
• ‘Legionella sp.’ 0 CFU
  

Add aquatic plants

Once the pool is completely watertight and the pH has been adjusted, we can proceed to add the aquatic plants.

We will choose the species that best suit our climate and our needs. In addition to adding beauty to our pool, plants also help to keep the water clean and healthy.

Incorporate biological filters

Biological filters are a fundamental part of natural pools.

These filters keep the water clean and free of impurities without the need for chemical products. To put them into operation, it is necessary to add a small amount of organic matter to the filter so that the bacteria begin to act. Once in operation, biological filters require little maintenance, although they should be cleaned and checked periodically.

Adding the finishing touches

To give our natural swimming pool a more attractive appearance, we can add small details that make it unique.

We can, for example, incorporate submersible LED lights to illuminate the pool at night, or create a relaxation area with deckchairs or sun loungers to enjoy the sun and the tranquillity of our natural pool.

We can also add decorative elements, such as stones, logs or flower pots, to complement the natural look of our pool.

By following these steps, you will have a fully functional natural pool ready to be enjoyed throughout the bathing season. By keeping the water properly treated and cleaning it properly, we can enjoy our bathing in a natural and ecological environment.

Final tips and ideas for decorating our natural pool area

Once our natural pool has been built, we can start thinking about its decoration and how we can enhance and personalise the surrounding area to create a pleasant and relaxing atmosphere. Here are some ideas and tips to keep in mind:

• Choose appropriate lighting for the pool area, preferably energy efficient lights with a warm tone.
• Add some comfortable loungers with cushions to relax on while enjoying the sun and water.
• If you want to give a rustic touch to the pool area, you can include wooden furniture and natural stone.
• Pergolas are a good option to protect you from the sun and create shade in the area. You can cover it with plants to give it a natural and fresh touch.
• If you are looking for a contemporary touch, you can opt for minimalist design furniture with neutral colours, which create a sense of harmony with the natural environment.
• Don’t forget to include elements such as a shower or a small bar to complete the pool experience.
• Add plants that complement the surrounding area of your natural pool. It is important to choose plants that not only adorn the area, but also help to maintain the natural balance of the water.
• Don’t over decorate, remember that the main aim is to create a calm and relaxing atmosphere.
  

Remember that the most important thing when decorating the natural pool area is to take into account its natural surroundings and opt for elements that suit and complement the environment.

With these tips and your personal touch, you will create a pleasant and harmonious area where you can relax and enjoy your natural pool.

How to build a natural swimming pool at home step by step

Excavating the site for the natural pool and designing it

The first thing to do is to choose the right place to start building your natural pool.

Our recommendation is to look at:

• The leaf fall of nearby trees.
• The shading that may occur during the day and that will affect the temperature of the water.

Once the site has been selected, we proceed to the excavation, following the previously selected design.

Soil preparation and placement of the first layer of gravel or clay

After excavation, the clay layer (normally 30 cm thick) is prepared, which will serve as a base for waterproofing and protecting the soil. It is important to ensure that the clay layer extends over the entire bottom and conforms to the shape of the pool.

Laying the liner and filter system

Once the clay is in place, the liner is installed to ensure a leak-free pool. Next, the filtering system is installed, which will provide better water quality and a natural regeneration of the water.

Areas of the natural pool: bathing area and regeneration area

The natural pool is usually divided into two zones; a bathing zone and a regeneration zone.

The bathing area is the one to be used for swimming and enjoying the water, while the regeneration area is responsible for treating the water, thanks to plants and micro-organisms, to keep it clean and purified.

These two functions can take place in the same tank, in separate tanks or in a mixed way and it will depend on our tastes and requirements to choose one or the other type.

Choice and placement of aquatic plants

In order to achieve a correct natural cleaning of the water, it is essential to select the right plants for our natural pool.

Aquatic plants oxygenate and purify the water, which is essential for its correct maintenance.

Filtering system and maintenance of the natural swimming pool

Once the natural pool has been built, it is essential to maintain the filtering and water treatment system correctly. In order to keep the natural pool clean and healthy, it is necessary to correctly manage the filtering system, to have a correct balance of nutrients in the water and to prevent organic materials from falling into it.

• Excavation of the site for the natural pool and design of the natural pool
• Preparation of the ground and laying of the first layer of clay.
• Laying of the liner and filter system.
• Zones of the natural pool: bathing area and regeneration area
• Choice and placement of aquatic plants
• Filtering system and maintenance of the natural pool

Types of natural pools.

Non-technified natural pool

This type of natural pool uses a vertical-flow biological filter integrated into the swimming pool. This filter also houses the plants, i.e. it is also the regeneration zone.

The water circulation is produced in a natural way by the heating of the water surface which circulates the water through the gravel filter.

The effectiveness of this natural filtering system is limited. It takes several years for the ecosystem to reach equilibrium and when it does it is not possible to guarantee complete transparency of the water, however it is not necessary for transparency to be complete for the rest of the water quality parameters to be correct.

Natural pool with recirculation

If to the system described in the previous point we add a pump to recirculate the water in the pool through the biological filter, we improve its behaviour considerably, being able to reduce its surface area. Aerators can also be used to fulfil this function of circulating the water through the filter.

Natural pool skimmer and filtering system

In the type of natural pool described in the previous points, all the elements that fall into the pool: leaves, insects… are either removed manually or become part of the pool’s ecosystem, increasing the levels of autotrophication.

By simply installing a skimmer and a filtering system, we can remove the organic matter that falls into the pool, making the system more efficient in an automated way.

Fully technified natural pool

A natural pool ecosystem takes some time to mature and function correctly. During this period we would have a proliferation of filamentous algae, unicellular algae which, without posing a threat to health, can be an aesthetic problem for some people.

Furthermore, in climatic zones with high sunshine and high temperatures, it is difficult to maintain a biological balance that prevents the proliferation of algae in the hottest seasons (which are also those in which the pool is used).

For this reason, a series of elements can be implemented to achieve a swimming pool with perfect conditions from the first moment, it is a completely technified natural swimming pool:

Sieve filter.

• This is a filter that automatically removes organic material from the pool.

Scrubber algae filter.

• This is a filter that encourages the growth of algae in such a way that they absorb the nutrients, preventing them from proliferating in other areas of the pool.

Zeolite filter.

• Eliminates ammonia compounds, one of the sources of algae nutrients.

Phosphate reactor.

• Removes phosphates, another of the main sources of algae nutrients.

It is not necessary to implement all these elements for the correct functioning of the pool, it is important, depending on the problem that we foresee, to equip the pool with certain systems in anticipation of possible problems.

If you would like to learn how to calculate the sizing of the filter pumps in a natural pool, you can sign up for our online course on natural pools.

Here is a video on how to transform a conventional chlorine pool into a natural pool without major works and without drilling the pool shell.

There are many tutorials and written guides on how to make natural pools, but sometimes a picture is worth a thousand words.

For this reason, here is a video explaining how to build a natural swimming pool at home. In the video, you can see the steps of the filtering system of a natural pool made in an existing pool.

In addition, it explains in detail how to keep the water clean and healthy without the use of chemicals.

The video is easy to understand and clearly shows how to create a natural pool at home, step by step.

For those who prefer to learn visually, this video is definitely a great help to get started in the adventure of building a natural pool at home.

Don’t hesitate to take a look at it and follow carefully all the indications that the video provides to obtain satisfactory results in the construction and maintenance of your own natural swimming pool at home.

Comments and frequently asked questions from users about natural swimming pools and their construction

The construction of a natural swimming pool can generate many doubts and questions, especially if you have no previous experience in the matter.

The following are some of the most frequently asked questions and comments:

• What kind of permits are necessary to build a natural swimming pool at home?
• Is it possible to build a natural pool without the help of a professional?
• What is the best location to build a natural pool?
• Is it necessary to dig a lot to build a natural swimming pool?
• Is it possible to build a natural swimming pool in a small garden?
• How can I take care of the aquatic plants in my natural swimming pool?
• How can I prevent the formation of algae and keep the water clean in my natural pool?
• Is it possible to use chemical products for the maintenance of my natural swimming pool?
• What is the approximate cost of building a natural pool?

These are just some of the most frequently asked questions that may arise when building a natural pool at home.It is important to bear in mind that each case is different and will depend on factors such as the space available, the materials used and the particularities of the environment.

In any case, it is advisable to seek the advice of a professional to ensure proper construction and maintenance of our natural pool.