Here's old video at the end of a water change (we pump the water into the tank via the mechanical filtration system) You can see the extremely swift current generated with a Reeflo Hammerhead pump and a venturi return nozzle. The oscars do a little body surfing in the swift current, and the venturi nozzle keeps spitting out air after the tank is filled. Love the aeration. Good thing it's enough aeration, because my knuckleheads destroy everything put in their tank. We started off with a bubble wand across the back of the tank - it didn't last very long. Sorry Jon M for slightly derailing your thread/