Yes thanks for that link as I have seen pictures of that tank before and wondered how the waterfall effect was created. Very cool concept but don't know how practical it would be with filters and current in a tank. I would assume that it was only on for the pictures.That actually seems rather cool. Thanks for the link.
Maybe an airlift. This is common in water treatment filters.One of the contest winning tanks from a few years back used a flow of fine white sand as the waterfall. I don't recall how it was pumped, and I'm sure the effect would be hard to maintain for very long, but it was beautiful.