Creating a Waterfall in a Planted Aquarium
Written by Andrew Nunn   

I was curious as to how the tank seen below, which took World Ranking 7 in the Aqua Design Amano 2007 Aquascaping Contest created the waterfall illusion. I had seen similar effects created by rising bubbles, but this seems to end before reaching the surface, meaning it is created using a different method, or there was a good deal of photo editing involved. However, a poster on my blog tipped me off to a website (www.xylema.net) that explains exactly how it was created, and it is quite creative. Let’s investigate how the effect is created. To start off, from the initial impression, the illusion appears to be created using rising bubbles that where either edited out with photo software, or vacuumed away into a hidden cavern.  I come to find out neither were the case. Bubbles play a large role in the mechanics of the illusion, but they are not what the viewer is seeing.  Instead, the viewer is observing a steady stream of falling sand.  That’s right,  sand.  

 

Through a cross section of the "waterfall” we can identify how the sand is used for the effect.  A tube and airstone blows bubbles up through a hidden space behind a  wall. This creates a vacuum of bubbles that drives a water current towards to the surface.

As the water rises, tiny grains of sand from a reservoir are pulled into the vortex current.  The sand grains move with the water current and drift out through an opening near the top of the wall, and fall back down the front side of the wall.  A strategically placed incline ramp at the base catches the falling sand grains and returns them back into behind the scenes reservoir.   The cycle is repeated and the viewer sees an endless cascading waterfall inside the aquarium.

This effect is not the most practical for everyday use. A very fine sand must be used in order for it to be lift with the current. The falling sand is affected greatly by other currents inside the tank, and it will inevitably fall outside of the reservoir.  With a filter running, it would probably blow the falling sand everywhere else in your aquarium.  I'm sure much tweaking is necessary to find the best type of sand suited for this application, and what size space behind the wall works best. How the sand is ejected from the top of the bubble column is also probably a problem area that requires a lot of attention and adjustment. It's hard to tell from the diagram, but the bubble column space most likely extends above the water line. This forces the water pulled up by the bubbles out the sand-ejection opening. Otherwise, the sand would continue to follow the current of bubbles and water up and out the top of the column (and you'd have a messy volcano effect instead of a waterfall!). The final effect, if done correctly, looks absolutely stunning in aquascaped planted aquarium.