Interesting.
I have seen it done with the tubes before which is cool.
They had a couple different applications on the sight, one of which was ugly as sin IMO (the one with the tanks corners meeting), the other with them side by side i thought would look pretty cool if were done with a lil more care (joints looked horrible lol) and decorated right.
I was thinking of trying it with a couple 10 gallons just as an expirement next time i have a lil extra cash or can find enough scrap acrylic, and see how it goes. Assuming i figure out the physics of it.
As i said I didnt take the time to read any of the directions, but it seems to me it would work on a vacuum set up...Fill the 2 bottom tanks past the bottom of the top tank, then pump the air out of the top one and it would suck the water into the top one, and i assume if sealed well, would hold the vacuum to support the water in the top tank once the pump was removed....
At lease that works in my mind, but then I've said that one before lmao