just use pumps?
just use pumps?
It seems the most difficult part of these designs (whether DIY or manufactured) is creating a single device that can both suck and purge reliably...why not just hook a pair of closed-loop little giant pumps to a dual wavemaker power center, set the returns at opposing ends of the tank, and dial the timing in so they turn on and off exactly as the surge reaches the other side of the tank (longer tank = longer time between surges)?
If you prefer a wider surge, then just spread the flow over several horizontal outlets...or even across a square matrix of returns (like a checkerboard).
With this system you can adjust exactly the placement and power of the surge...no belts, boxes, obtrusive sounds, or headaches.