I removed the bottom and extended the Vortex tube to the gravel,
and I got this silent effect that my fish all seem fascinated with.
the 1mm gravel keeps recycling so the effect never stops, but
I have a feeling the plastic will get chewed away after a while.
hmmm, come to think of it, if it went any deeper it might chew
away my water retaining silicon fish tank seam
and yes, it's in focus, well lit, and done with the use of a tripod
Now for the World Premier of:
SpyPet's Vortex GRAVEL
100% Co2 Diffusion Reactor! 
<--click here