They’ve been around for almost 30 years now, having originated in Europe, where they are called swimming ponds. But many Americans are just becoming aware of this alternative to the typical chlorine-scented, eye-reddening swimming pool. Natural pools use plants and gravel to filter water, rather than relying on chemicals.
Natural swimming pools combine swimming areas and water gardens. Materials and designs vary — the pools can be lined with rubber or reinforced polyethylene and may look rustic or modern — but they all rely on ‘regeneration’ zones, areas where aquatic plants act as organic cleansers. The pools have skimmers and pumps that circulate the water through the regeneration zone.
Owners need to adjust to the idea of their pool as a living ecosystem and master the maintenance particular to natural pools — trimming dead plants; fishing debris and the occasional snake or turtle out of the water. It’s not for everyone. But the advantages include infinite design possibilities to give the pool year-round visual interest.
For further reading, see these articles:
http://www.motherearthnews.com/diy/natural-swimming-pool-zmaz02aszgoe.aspx
http://www.gardendesign.com/water/natural-pools.html
http://inhabitat.com/natural-swimming-pools-let-you-beat-the-heat-and-ditch-the-chemicals/
http://organics.org/16-natural-swimming-pools-that-you-wont-believe-are-real/
For the large part, the typical pool will take anywhere from six to eight hours to completely circulate. Exactly like any in-ground pool, an above ground pool ought to have a functional pump and filter system.