Eco Pool Gardening – Swimming Pools

When flying over densely populated parts of South African suburbia, you have the opportunity to peep into many urban backyards containing conventional swimming pools kept in pristine condition with the help of chemicals, permanently sucking vacuum cleaners and frequent manual maintenance by the owners.

The gardens surrounding these unnatural-looking blue expanses of water are normally palm-filled and quasi tropical simulating an exotic island resort. Sterile areas of paving and manicured lawns around the swimming pools edges are also prevalent.

There is, however, an alternate way to create your private backyard paradise – build an eco-friendly, chemical-free swimming pond fringed by aquatic plants which do most of the work to keep the water clean and clear. This concept is a world-wide trend and is fast becoming fashionable in South Africa.

When garden designer, Riaan Maritz, from The Garden Company was tasked with the design of the garden, including a swimming pool, for a holiday home bordering on the Fernkloof Nature Reserve in Hermanus, he realised that building a conventional pool and pool garden would be sacrilege in this beautiful area. He studied the free-flowing forms of the surrounding mountains in the background and based his overall garden design on relaxed curves and informal lines.

As the back garden was on a steep slope, two level terraces where created by building a curving retaining wall with natural stone, sourced locally. The large top terrace houses the swimming pond, a wooden deck, a meandering pathway and densely planted fynbos species mixed with other indigenous plants. The smaller, bottom terrace adjoining the covered veranda of the house, consists of a small lawn planted with indigenous buffalo grass.      
 
Natural swimming ponds are a chemical-free combination of a swimming area and bog garden. The two regeneration zones of this pool which filters and cleans the water naturally, is clearly visible.

Although you may imagine conditions in this swimming pond to be similar to those in your grandfather’s old farm dam – filled with slimy algae, a muddy bottom and croaking frogs – it is definitely not the case in an eco-pool designed and run by experts who understand the secrets of an aquatic ecosystem. But, you might encounter some happy frogs, hovering dragon flies and other little water-loving critters while taking a dip in ‘soft’ water untainted by chemicals.

The Swimming Pond
Riaan explains that the actual building and filtering systems of a natural swimming pond such as this needed the expertise of Dr. Jerome Davis from Aqua Designs, a company which specialises in aquatic bio-engineering, as well as Lourens Theron from Theron Broers Building Contractors in Hermanus.

Basically, the natural system working around and in this pond consists of different filtering layers. There is a top wetland area – a large, raised plant box next to the pond which is filled with bog plants in a substrate of coarse bark and a thick layer of gravel. The stone and bark act as an anchor medium for the plants which create a habitat for the micro-organisms which break down pollutants, while the gravel acts as a natural filter.

Water is continuously circulated and pushed through this wetland area over a small waterfall which aids oxygenation, into a lower wetland zone, a beautiful water-lily pond apart from, but adjacent to, the actual swimming area. The water is sucked through the water-lilies, another regeneration zone, which clears it of further impurities before it is circulated back into the swimming area. At first glance, the pristine-looking, egg-shaped swimming area looks quite deep and dark, but a slip-free wooden deck leads onto two wide steps just below the water surface, creating a shallow and safe area for children to play.

In the regeneration zone or bog plant bed, a coarse substrate like gravel is used rather than soil which brings high levels of nutrient to the water, counteracting the cleaning effects of the plants, while contributing to silting. Marginal plants planted in gravel are forced to draw nutrients from the water and in the process clean the pool.  

Calopsis Paniculata, this is a restio which likes to grow beside streams.  

Typha Capensis (Bulrush)  

Nymphaea Capensis (Cape Blue Water Lily)  

Kniphofia Praecox (Red Hot Poker)
These plants like boggy areas.  

Acmadenia Heterophylla (Buchu)  

Diascia ‘Cranberry Red’ 

A combination of Restio Festuciformis and Lobostemon Fruticosus (Pajama Bush) 

This shows the marsh-plant filtering system through which the water is circulated over a small waterfall into the second regeneration zone next to the swimming area.

Maintenance of the Pond and Garden
The Garden Company maintains the chemical-free swimming pond by gently vacuuming the bottom and brushing the sides regularly. They also care for the water plants by dead-heading flowers, pruning when needed and thinning out when they have grown too dense. As far as the rest of the garden is concerned, they stick to a regular pruning program to keep the fynbos plants like the leucadendrons, leucospermums, confetti bushes and proteas in good shape after flowering and to divide and re-plant perennials and groundcovers which have grown too vigorously.
 
Garden Notes
This is a medium to small garden of about 400 m2 which is situated in a housing complex in Hermanus. The soil is sandy and poor but suitable for fynbos species of which many are endemic to this region. The climate is temperate with hot and dry summers and winter rainfall. It is still a young garden, only 3-4 years old. It was photographed in April 2012.