You'll want a shallow section where your plants and ecosystem can take root without being disturbed, this zone is usually about the same size as your swimming zone. Ensure that your regeneration zone isn't placed at the very bottom of your yard or property. Drainage must be considered in the case of rainfall and runoff -- you'll want to prevent this flowing into your regeneration zone as much as possible.
Instead of building an entirely separate pool, you can also build a shallow shelf which surrounds your swimming zone. This should be impounded with a submerged shelf so that plants don't slip into the swimming zone.
