http://www.drsfostersmith.com/Produc...&N=2004+113782
Switching Current Water Director (SCWD)
* Produces waves with your existing pump
* The most energy-efficient wavemaker available
* Bi-directional water movement
SCWD uses your existing pump to create bi-directional water movement in your reef aquarium. Plumbed inline, SCWD directs incoming water to two alternating outputs, switching automatically at a rate depending on incoming pressure. It delivers quiet, smooth operation, and is clog-resistant. Features low back pressure so there