A review of five different natural swimming pool (NSP) designs

by Sally Bouorm | March 1, 2014 4:04 pm

[1]

By Markus Winkler and Karen J. Williams

On the surface, natural swimming pools (NSPs) look like a natural garden pond; however, they are in fact much more. They are specifically designed so people can swim in clean, pure water without the use of any chemicals. A NSP or swim pond comprises two zones: a deep, central swimming area, and a shallow surrounding area, which encompasses various plants specifically chosen to filter the water.

NSPs originated in central Europe, specifically in Austria and Germany, more than 40 years ago with most still offering owners a unique bathing experience. In the last 20 years, an increasing number of people have become more health and environmentally conscious, seeking to provide a healthier environment for themselves and their families. Many may believe energy is the main concern for the next generation; however, water—one of the most precious resources—must also be preserved. By supporting the NSP concept, families can still enjoy a wonderful swimming experience, while at the same time being environmentally friendly.

The concept is different from a traditional swimming pool wherein water is lost via system flushing and seasonal drainage. NSPs, on the other hand, preserve, retain, and use as much natural water as possible. For example, the concept of rainwater harvesting can be used to top-up and fill a NSP.

A different type of swimming environment

Back in the ’80s, the idea of manufactured NSPs came from nature enthusiasts who were looking to create a chemical-free and biologically acceptable swimming environment. The first pools were more like garden ponds with clay bottoms and wooden barriers to separate the swimming and wetland areas.

More recently, however, the NSP market has developed in two directions: one for true nature enthusiasts who want an absolute pure, biologically sound body of water, wherein most of today’s modern water treatment technology is not used; and one for those who prefer a swim pond that uses biological water filtration combined with the use of environmental technology.

The latter has also been used in countless projects in the public authority sector for public and/or community pools as well as in hotels and resorts around the world.

The necessary technology is available, and with the proper training and coaching, there is no doubt this type of water body option will change the traditional swimming pool market as a whole.

Five ways to build a NSP

[2]

There are many ways to design a NSP or swim pond—from contemporary-looking swimming pools, which use different long-lasting membranes or concrete shells with special-mixed concrete, to those that look like mountain-side lakes with the use of natural stone and gravel built on top of the swim pond membrane. The builder’s ultimate goal is to create a design that makes everyone think the house was built next to a lake; therefore, natural cohesion between the home and NSP is paramount.

Those interested in the idea of an NSP must make a few decisions first before going ahead with the general design. Therefore, the first question a builder should ask their client is which type of natural pool will best suit their needs. It is also important the client becomes familiar with the five different types of NSPs. They are as follows:

Type 1: 100 per cent Mother Nature

More than 40 years ago, NSPs were designed based on limnology, e.g. lakes and other bodies of fresh water, which rely completely on Mother Nature’s capabilities to clean and purify water through biology. These swim ponds contain a complete range of wildlife and have a great deal of biomaterial floating in the water—no water treatment technology is used.

[3]

After three-to-five years, this type of NSP will be balanced on Mother Nature’s terms. Too much cleaning will hinder the ecosystem rather than help it; therefore, an annual cleaning should suffice. The size of the wetland is also important. In this case, two-thirds of the entire water surface should be developed as wetland to provide a substantial system for proper functionality—the larger, the better.

The planted area should also be well-equipped with a shoreline, plants, and underwater vegetation to create a home for all of the water purifying organisms. The plant realm should have at least 1 m (3 ft) of water at the deepest areas as well enough shallow spots and shorelines should be constructed to properly support Mother Nature.

The biodiversity of the fauna (i.e. animal life) for these ponds are very high and complex with cohabitants, including turtles, dragon flies, frogs, and salamanders.

Some points to consider when building this type of NSP:

1. Use approximately 25 different types of shore, swamp, and reed plants.
2. Use roughly five to eight different types of underwater plants.
3. Use three to five varieties of floating plants.
4. No use of pumps or skimmers.
5. Water depth for the plant zone must be at least 1 m (3 ft).
6. The regeneration zone should be a minimum 50/50 to an ideal two thirds of the entire pond surface.
7. Minimum water surface should be 139 m² (1500 sf).
8. This is the most inexpensive type of NSP.

Type 2: Minimal technology

[4]These swim ponds were introduced in the late ’80s and use a minimal amount of technology to purify the water, mainly for circulation. Many of these NSPs are equipped with small water features to manage some needed circulation of the pond water.

Those who select this NSP design accept the fact there will be a high amount of sediment (similar to Type 1), as well some algae in the water.

[5]

Pumps are typically installed on these NSPs to circulate a limited amount of the entire pond water; however, not more than 10 to 20 per cent per day. The circulation supports the biological processes and distributes nutrients and oxygen in the pond, allowing the plants to handle the remainder of the water purification duties.

Some of these NSPs also have small skimmers to deal with leaves and/or other floating debris on the water surface. The use of a 24-volt pump should be sufficient in providing the necessary circulation.

In general, ‘Type 1’ and ‘Type 2’ NSPs work within the same principles and guidelines; however, there are some differences to the size and/or use of technology. If space is limited and the client wants some help in keeping the pond water clean, this may be the option for them.

Some points to consider when building this type of NSP:

1. Follow points one through three for NSPs ‘Type 1.’
2. Use a 24-volt pump and a flow rate of approximately 7000 litres per hour (L/h) (1849 gallons per hour [gph]).
3. The regeneration zone should be a minimum 50/50 of the entire pond surface.
4. Minimum water surface should be 74 m² (800 sf).
5. The swimming zone depth should be a minimum 2.4 to 2.7 m (8 to 9ft).
6. This is also an inexpensive NSP.

Type 3: A popular choice

Many select this type of swim pond because it still provides the natural appeal of a ‘Type 1’ and/or ‘Type 2’ NSP, but at the same time providing different advantages of all five NSP designs (see below for further detail on ‘Type 4’ and ‘Type 5’ designs).

For instance, the basic elements from the NSPs described above are still used; however, these swim ponds integrate filtration concepts and technologies to purify water. Many of the technological devices save the owner work when it comes to maintenance. For example, the focus of the design is still natural, such as a mountain-lake pond; however, the NSP is equipped with the necessary technology to keep the water of the swimming zone mainly free of sediments and algae.

Another advantage to this type of NSP is the fact it will have fewer nutrients than its ‘Type 1’ and ‘Type 2’ counterparts, thus keeping the water clean should be less of a hassle for the owner. Fewer nutrients mean less sediments; the water purification process focuses then on removing nutrients rather than allowing them to remain in the water to a higher degree as is the case in the former types.

Typically installed in an external compartment, these swim ponds use a powerful pump to circulate the entire water volume within 24 hours through the filtration areas. With a focus to have the main current on the water’s surface, this system allows leaves, debris, sediment, and dirt  to move toward the skimmer or overflow spillway for instant cleaning.

Some points to consider when building this type of NSP:

1. The regeneration zone should be similar to ‘Type 1’ or ‘Type 2’ NSPs.
2. Use a powerful circulation pump to circulate the entire pond within a 24-hour period.
3. Minimum water surface should be 74 m² (800 sf).
4. Most common NSP.

Type 4: Swimming pool conversion

[6]

In the last number of years, ‘Type 4’ swim ponds have become extremely popular with homeowners looking to convert their traditional swimming pool into a NSP. These projects are typically for those who perhaps are allergic or have respiratory issues with traditional pool sanitizers.

These swim ponds provide homeowners an esthetically pleasing way in which to create a more natural landscape in their backyard. The circulation equipment used for ‘Type 4’ NSPs circulates the entire water volume one to two times within a 24-hour period. For these NSPs, hydraulics is more important, whereas the wetland, or regeneration area, can be minimized to 35 to 40 per cent of the entire water surface. In terms of construction, they are often built in a two-part system wherein the regeneration zone is its own separate entity and external to the main swim pond area.

From a design perspective, this concept provides a number of unique ways to create a smooth transition from the hardscape of a house into a natural wetland.

Type 5: Just for looks

‘Type 5’ NSPs still provide a chemical-free swimming experience, yet provide traditional swimming pool water purification, which is accomplished via technical systems. Therefore, the plant life is more of an esthetic component of these swim ponds and do not serve any real functionality as they do in the previously mentioned NSPs.

Water purification is maintained mainly by bio filters and substrates, which bind the phosphorous and hinders the opportunity for algae growth. In this example, the entire water volume is circulated many times over a 24-hour period.

A hybrid option

[7]

In general, builders mainly use the principles of a ‘Type 3’ swim pond and combine essential elements from ‘Type 4’ and ‘Type 5’ NSPs to create a hybrid option for clients. These NSPs provide an active water depth of 2.7 to 3.6 m (9 to 12 ft), allowing the owner to see every single rock at the bottom of their pool.

 

Markus Winkler is the master designer and lead strategist for PoolsByNature, a designer/builder of natural swimming pools (NSPs) in Kelowna, B.C. He has more than 12 years of experience in the field of NSPs. Winkler has an engineering background in electronics and has received extensive education with respect to environmental and aquatic applications. He can be reached via e-mail at poolbynature@gmail.com[8].

 

Karen J. Williams is the design analyst for PoolsByNature. She has more than 20 years of experience in environmentally sustainable product strategies and is a member of the design team responsible for the connection between licensee partnerships and end-users while working with the company’s master designer.

Source URL: https://www.poolspamarketing.com/trade/a-review-of-five-different-natural-swimming-pool-nsp-designs/

---