Natural Swimming pools

These look brilliant. They provide natural clean water, chemical free "with lasting beauty year round". Who wouldn't want a crystal clear swimming pools that uses natural aquaculture.

Sanarfil say:

Pools and Ponds | Natural Swimming Ponds - Guaranteed pleasure
The natural swimming pond is the ideal synthesis of the element water and an enchanting plant world. Joy, simple pleasures, and quiet moments await you here in the midst of nature. Your own natural swimming pond is the perfect place.

Amazon has this amazing book on it (click on the cover on the left) which I found after a spotted this photo of a simple design on flickr which then also led me to Pond Doctor Daves web site (which has a few links and pics).

If you work in travel in SA, please consider where someone could build one. I have no doubt it will attract a great deal of attention, great marketing idea.