Most people have never heard of a living pool– if that’s you, you’re not alone. Living pools are an exciting way to merge the joys of a swimming pool with the beauty and sustainability of nature.
So what exactly is a living pool and how does it work? Let’s dive in.
What defines a living pool?
A living pool is the biological version of the conventional swimming pool. Similar to its chlorine or saltwater cousins, a living pool fundamentally is a sealed, contained, watertight vessel that uses a pump to circulate the water.
The key differences are:
- That it has a plant or “regeneration” zone. The planted zone is separate from the swimming zone so that the swimmers do not disturb the plants.
- There is no use of chemicals or devices to disinfect or sterilize the water. The water is clarified and purified by pumping water through the natural biological systems.
What a living pool is *not*
When you think about putting a water feature in your backyard, the first thing people may think about is a standard chlorinated pool, or perhaps even a man-made pond. Another option that’s gaining popularity as an alternative to chlorinated pools is a saltwater pool. They are all different from a living pool, however.
Chlorinated pools
Many above and below ground pools use chlorine to sanitize the water and help protect swimmers from waterborne germs. Chlorine (or bromine) also keeps working long after it is added to pool water, providing a “residual” level of protection against germs.
Once chlorine is added to the pool, it forms hydrochloric acid which disables harmful bacteria, viruses, and other microscopic dangers by combining with them. Combined chlorine is also known as chloramine. In these kinds of pools, it is crucial to get the pool chemistry right.
Most in-ground pools are made of either concrete, or a mix of vinyl or fiberglass with concrete. A vinyl liner pool is generally a prepackaged pool kit in which the liner hangs from wall panels made from aluminum, galvanized steel, plastic or pressure-treated plywood. Chlorinated pools also use an external filtration system to circulate water and catch any small debris. Many people may also choose to add external pool heaters and chillers.
While the bacteria-killing properties of chlorine are very useful, chlorine also has some side effects that can be annoying to humans, and possibly even hazardous.
Saltwater pools
Believe it or not, saltwater pools are actually a version of chlorine pools! For a saltwater pool, instead of adding chlorine to the pool water, you add salt, and a generator converts it to chlorine. After being filtered, the pool water flows through a cell. Inside, a series of metallic grids with a low-voltage current create a reaction that converts the salt down to little bubbles of pure chlorine. This pure chlorine reacts with the water to form hypochlorous acid, which is what cleans your pool.
In addition to the generator, saltwater pools are built similarly and also use an external filtration system like their normal, chlorinated counterparts.
For these pools, the “salt water” is about 1/10 the salinity level of the ocean—it’s more like a teardrop or contact lens solution. Over time though, salt can degrade metal objects, like heaters, ladders, diving board brackets, and more.
Ponds
Natural swimming pools and ponds can look strikingly similar at first glance, but there are some very important differences between the two. The biggest difference is that a pond is a small area of still, fresh water. It is different from a river or a stream because it does not have moving water and it differs from a lake because it has a small area and is no more than around 6 feet deep. Some ponds are formed naturally, filled either by an underwater spring, or by rainwater; other ponds are artificially made.
Natural or man-made ponds also are typically 50% plant life, which helps keep the water clean and clear. Ponds also can not be heated or covered.
How is a living pool built?
In the most fundamental sense, a living pool is a swimming pool. Therefore, designs and construction follow common build guidelines. A living pool is typically constructed using gunite with a plaster finish, a prefabricated set of steel walls with a PVC membrane, or a composite equivalent. This closed-circulation structure prevents outside water sources and runoff from getting into the living pool.
A living pool is constructed with a wall separating the swimming zone from the regeneration zone, which most closely resembles a natural pond. This design does typically have a larger surface area than standard pools (a minimum of 650 sq ft.) in order to incorporate the regeneration zone.
A pool with plants
Natural pools eliminate the tediousness of chemical testing and water balancing, allowing the water to reach its own natural balance. This system simply relies on environmentally deposited nutrients (from the atmosphere and bathers) to “feed” the elegant complexity of the biological ecosystem to naturally clean the water. A naturally purified swimming pool nurtures and employs helpful microbes to consume and convert these nutrients into energy to survive or to filter waste.
Algae and other phytoplankton species are naturally occurring microbial plant life. The living aquatic environment we are creating relies on healthy – but controlled – growth of phytoplankton and other producers in the microbial lifecycle. A natural pool will always have some algae in it, but algae is kept in check with the correct assortment of aquatic plants or a biofilm filter.
Plantlife enriches the pool with oxygen and supports beneficial bacteria that consume debris and potentially harmful organisms. The result is a beautiful, ecologically diverse system. The water needs to circulate continuously for the plants’ roots to cleanse the pool. You also may need to aerate the water so the organisms’ oxygen needs are met. A good way to naturally aerate your living pool is by adding a waterfall or other water feature.
Nature begets more nature
Some people like being in touch with nature. Others, less so. The beauty of a natural pool is that it can attract friendly life. Many people worry that it can attract not-so-friendly life, like mosquitoes. The good news is that the water in living pools is always circulating, which means mosquitoes are not a problem as they do not breed and lay eggs in moving water. A more significant concern for mosquitoes near your living pool would be potted plant bases, or any place water can gather and remain stagnant.
With the lush, green plant life living in your regeneration zone, it can give habitat to frogs, dragonflies, and other life that call water or marshy lands home.
While some people might be inclined to include fish in their natural pool (like you might find in a pond,) unfortunately fish consume beneficial zooplankton which can upset your natural pool’s microbe community. While fish would really love your pool, the biggest reason they shouldn’t be living in it is that they put an undue load on the system with their waste.
A year-round feature
One of the convenience factors of having a chlorine or saltwater pool is the temperature control you can have by installing a heater or chiller.
The good news is you can still enjoy that same control over the temperature in your natural pool. However, controlling a natural swimming pool temperature can be a delicate process to maintain natural, living water. It’s important to keep the temperature range between 50ºF-90ºF. Aquatic plants in regeneration zones may be adversely affected by heat above 90ºF. Although warmer water generally aids in aquatic plant growth, sharp fluctuations in temperature can shock the plants.
How much you can heat the pool also depends on your climate and the time of the year. Living pools tend to be warmer than traditional pools because the biological filter is relatively shallow and acts as a passive solar collector. With use of solar panels, you can heat the pool during the day, or cycle the panels on at night when the air temperatures drop to cool the water.
Once the temperature drops below 50ºF, the microbial life will go into a dormant state. The benefit to having a natural pool is that you don’t have to drain the water at the end of the season– you can let the water freeze over and even skate on it in the winter! The water plants we typically use are locally-sourced, hardy perennials that die and grow back each year with no problem (just like in any garden).
Your own backyard sanctuary
While a living pool is a relatively new concept to most people in North America, they are becoming more and more popular and accessible. If you’ve always wanted a sanctuary in your backyard, but have been wary of installing a pool because of the potential negative effects of chemicals on yourself and the environment, we have options to bring your outdoor oasis to life.
While they’re built similarly to traditional swimming pools, living pools don’t use chemicals or salt water to function. They’re an eco-friendly alternative that creates a peaceful, serene space that’s pleasing to the eye and neighboring wildlife all-year round.
We understand that you may still have some questions about living pools or you might be interested in taking the plunge of setting one up in your backyard. Please get in touch with us, we’re happy to help you learn more and see if it’s the right choice for you!