Who said power heads are unsightly was bang on. I looked at Jacks return loop on his older tank (60 gallon) I think and it was an awesome set up. I tried plumbing a couple of Mag3's into some PVC and having it branch out behind the LR in various areas when it was all said and done it still looked cumbersome and unsightly. I was also thinking of putting a float switch on a pump to return the water from the sump but that was kind of kiboshed through domestic issues. I thought a 50 gallon sump with a small holding area and the float switch to push most of the water back to the main tank then switch off when the water level got to say 3 inches deep in the sump have that on a timer so during the day I had lots of movement then at night just have a smaller pump running for less surge(less noise).
I think what we really want rather than tons of water swirling around is that back and forth surge, on a real reef there isn't all these little currents always but there is always the motion of the ocean
that surge is what moves nutrients to the corals and moves debris away. I think that toilet plunger idea is an excellent one, I wonder what size of refugium/holding tank you'd need to get the full effect of the surge.
To reduce bubbles what about putting in a trap, lower than the surface of the water, then have the tubes come back up and into the tank, that may reduce some of the bubbles... or maybe I'm way off track.
Doug