Natural swimming pools and ponds are making a splash in the UK and European market
Standard outdoor swimming pools, though luxurious, are a bit footballers’ wives for many of us.
That chlorinated sparkling tank of blue under grey, groaning Irish skies I often wondered if the rare examples I have seen, have a giant immersion switch in the pool-house.
Slow swags of river, ponds and natural swimming holes have such a different feel.
The water is soft, almost oily, and there are blessed warm shallows heated by the sun where you can bask like a happy otter. Plants fringe the perimeter, and wade in to greet you.
There are fish, water creatures, and deep fathoms where you tread water over depths that seem to run down to forever.
Natural swimming pools and ponds (NSP) are making a splash in the UK and European market, and with rich emerald hue and surprisingly clear water, they can be as sophisticated or rusticated as you like.
In Kings Cross, London, the first community NSP is now open to the public, based like all true NPSs on a wetland eco-system that (with a little clearing), tends to itself. The temperature varies from 13°C to 21°C on a nice blazing hot summer’s day.
Developed in Austria in the 1980s, the ecological balance of a true NSP relies on what is termed a ‘regeneration area’ of shallow beds adjoining the pool but separated from the actual swimming.
Taking up between 30%-70% of the entire area, these are planted hydroponically with oxygenating plants at varying depths — such as reeds, lilies, water mint and other marsh loving species.
Lapped by the water, the right plants and minerals consume harmful bacteria, decontaminate the water and interfere with the growth of algae that can cloud it up and alter the pH.
A standard swimming pool can be converted to a chemical free, biologically managed pool with ‘living’ water.
Filling with fresh water (preferably bore water) free of chlorine, the water is tested and then balanced through the addition of minerals to bring it to the correct PH, removing heavy metals and other toxins.
Once the pool has settled for a month or two, excess bacteria that occur in the water are mechanically ‘skimmed’ using a pump and fine filters which remove excess phosphates and nitrogen, rather than killing off all organic activity good and bad, with bleach heavy ingredients.
Ultra violet light removes algae and germs harmlessly. UV is not an ingredient in a true NSP and a classic NSP really must include planting.
Andrew Baczynski is MD of AquaSystems, in Dungarvan and explains: “The plants are placed no deeper than 30cm to recreate their natural wetland environment.”
This vegetation is set in an impermeable membrane, partitioned from the swimming areas with border walls below the water line to allow water to flow over the beds.
The walls can be attractively coped in brick or stone and flowering species used to ornament the working plants.
Converting a traditional pool to a NSP, involves a new filter system and creating suitable planted beds, but you will drop your running costs for water heating and chlorinating the pool.
The water colour will never be crystal clear, but you should be able to see the bottom through a briny green. Prices for a pool conversion start in the area of €22,000.
These styles of swimming pools are very much part of the garden’s landscaping, with the water condition managed both mechanically and biologically with vegetation, robotic skimmers and passive filters rather than potentially allergenic chemicals.
Concrete sided NSP pools can be highly urbane, not recalling a natural pond at all, if you prefer.
Fish can be included in separate ponds but apart from being distressed by disturbance, require a pH of around 7.8 to 8, where human skin is most comfortable at a pH of 5.5.
The ultimate sylvan swim, natural swimming ponds or Schwimmteiche, aims to be as close to their natural inspiration as possible.
They are created in the same way as you would create any fish or wildlife pond.
A pond starts with digging out, installing a drain, and lining with a heavy gauge UV and algae resistant liner.
There are a variety of depths, one of at least 2m to ensure healthy bacteria can survive at the warm bottom of the pond when the temperature falls to less than 8°C in the winter.
A dedicated bacterial spray or blooming buckets of water from a healthy local lake is used to kick-start the metabolic process in the regeneration area.
The amount of open water and shading is vital, as algae thrive in direct light.
Andrew Baczynski emphasises the importance of the drain, ‘silt gathering on the bottom of the pond can hold ammonia which can be kicked up when you swim. We always gauge the wind direction first when installing to ensure the silt is carried the right way.
There’s a valve at the end of the drain that can be opened to just dump the silt out.’
“The larger the pond the better,” explains Andrew, “not least because a larger surface area allows for a larger swimming area and for a breeze to ripple and move the water towards the regeneration area, and the silt on the bottom towards the drain.”
He recommends a size of no less than 100m for a pond, and says that 150m or more is much better.
“The greater the degree of planting the less invasive technology is needed to keep the water clean. Moving the water through say, a cascade, improves the speed of purification through the planted regeneration area and onto the skimmers.”
Maintaining a natural pond or pool (with planting), has a degree of gardening in it and it really depends on just how pristine the user demands this special environment to be.
Occupying a large area of the reservoir, plants must be thinned and cut back to prevent them invading the swimming zones, and they will of course need some feed during the growing season.
The pond is vacuumed by hand with a large hose as needed and an automatic surface skimmer can be used to patrol the surface, removing debris. Every few years, the silt bed that will inevitably accrue on the bottom of the pool must be taken out and this can demand the pond or pool is at least partially emptied.
Overgrowth of algae is pulled out by hand and slopped into buckets as needed. Andrew describes this work as ‘very manageable’.
Setting up an ecologically stable NSP involves hydraulic design and hydroponics applied on a large scale. To avoid spending thousands on a vast, greasy puddle, invest in expert help.
Most of us are restrained to the use of wildlife and fish ponds in the garden, but they are a stirring addition and well worth the trouble. Here are some key considerations to start your journey.
* If you have under fives in your immediate or extended family who are likely to use the garden — forget the pond for a few years or install a grid right below the water surface. Try pondsafeysystems.ie
* Consider where water runs in the garden during heavy rain. Is the water table likely to rise underneath the pond’s position? Will you have to disturb the foundations of any garden walling? A raised pond can eliminate these problems.
* Try to ensure a fish pond is placed out of cold prevailing winds, and receives sun at least during at least half of the day to encourage water plants to flourish. 40% of the area should be at the deepest measure recommended for your chosen species and size of fish (full grown).
* The pond should not be overhung with trees, especially those with toxic leaves such as laburnum. Skimming off leaves several times a day is a nuisance chore.
* Shelving areas (30cm and less) are needed for those biologically filtering plants used in natural swimming pools too. For crystal-clear water you will need a bio-filter and UV filter.
* A pond can be any shape, but the more complicated it is, the more ‘folds’ the greater the area you will need for a liner. Think about softening the edges with plants rather than dreaming up over-complicated designs that could prove a headache.
* Any cascade or waterfall should be in ratio to the size of the pond to prevent turbulence.
Ensure you provide a ramp for creatures to get in and out of the water safely.
Young hedgehogs, birds and mammals that come to drink, can easily drown in a small pond.
