||Does low-maintainability mean installing lots of filters, chemicals, concrete, and no fish or plants?
Yes and No. The primary key to low maintainability is to design and maintain the pond and waterfall in concert with nature and natural biological systems. This is not Zen, but simply biology, correct technique, and common sense. Does a natural crystal clear pond, with fish and water plants use mechanical filters, swimming pool chemicals, or concrete?
The secret is building a man-made environment that is designed correctly to work, and then is allowed to remain in balance with natural biological processes. Fish and plants help achieve this balance. If you accomplish this, maintenance is at a level no higher than any other landscape feature. A mechanical skimmer, and yearly clean out of the pond should be all that is necessary.