I don't know if this link will work, but they are commonly called "organic pools". I think this might be what you are after? If the link don't work, do your own search. Notice the rock edges that create the swimming area, and then the shallows for plants. They frequently have a waterfall feature of some sort to help with water quality too.

https://www.bing.com/images/search?q=org...lay&first=1