Nov. 19, 2019
No chlorine, no harsh chemicals. Just natural filtration.
We're not talking about a koi pond. We're talking about a public swimming pool.
North America has two all-natural public pools: Webber Natural Swimming Pool, which opened in Minneapolis in 2015, and Borden Natural Swimming Pool in Alberta, Canada, which opened last year.
Both pools have crystal-clear, health board-approved water - even without chlorine.
How do they do it? The same way we keep our ponds clean: a combination of plants, rocks and micoorganisms.
The Minneapolis pool has a more than 16,000-square-foot "regeneration basin" filled with layers of limestone and granite gravel, as well as more than 7,000 aquatic plants. All of the pool's 500,000 gallons of water cycles through this basin once every 12 hours. This system - with some help from regular vacuuming to remove physical debris - keeps the water safe.
The pool in Alberta uses similar natural filtration. A "Neptune Filter" made of layers of granite rock filters out large debris, while biofilm on top of the rocks filters out microorganisms. Plants in the hydrobotanical beds take phosphates, nitrogen, carbon dioxide and other contaminants out of the water, and intense ultraviolet from the sun controls bacteria levels.
Borden Park is Canada's first chemical-free public swimming pool which uses natural filters like stone, gravel, sand, and an ecosystem of plants and microorganisms to keep the water clean pic.twitter.com/LaYhJMcGx4
— Unrtd.co (@unrtd) September 8, 2019
Does this all sound familiar? It should. It's similar to the system we use in our Ecosystem Ponds.
Ecosystem Ponds are manmade water features that use some clever tricks to mimic natural processes. A skimmer removes physical debris. A biofilter gives beneficial bacteria - the stuff that prevents your water from turning green - a place to colonize. Gravel on the bottom adds even more nooks and crannies where good bacteria can grow, and plants filter out excess nutrients.
This system has helped us create ponds with crystal-clear water and happy, healthy fish for more than 30 years. It works in everything from tiny goldfish ponds to acre-sized swim ponds.
It might even work in your local pool.