Don't Jellyfish need rounded corners?

Since the 1960's jellyfish have been kept in plankton kreisels that are formed from a rounded sheet of acrylic secured inside an acrylic tank. This circle or oval shape is the framework that aids the incoming water to create current that suspends the jellyfish. A circular, gentle current is created as a result, and the jellyfish remain in motion. 

In the 90s, public aquariums took a step away from Kreisel tanks, and ventured into the square-flow arena. The Jellyfish Tumbler tank was born. This new way to experience jellyfish keeping uses a spray bar to direct flow down over the filter plate, then out across the bottom, keeping jellyfish suspended. The most important aspect of this design is that the jellyfish experience a more natural existence than with a kreisel. The traditional kreisel keeps the jellies in a whirlpool, which they do not experience in nature. The tumbler tank offers a gentle up and down flow which simulates natural currents of the sea. This flow stimulates proper feeding and bell development, leading to happy and healthy jellyfish. 

The JellyKeeper drop in filter converts standard glass aquariums into a Jellyfish tumbler tank. The hidden spray bar creates a flat curtain of flow over the filter plate, keeping the jellies safe from harm. Water passes through the filter plate, then up over the overflow before entering the back filtration area. JellyKeepers come equipped with room for a Red Sea nano-mat or filter cup. Space is also provided for the Sicce protein skimmer, and room below for biological media.