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

Type 2: Minimal technology

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.

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.