The Gyre has three modes - steady flow, pulsed waves with a short period (many seconds to a couple of minutes), and laminar/turbulent with a longer period (several minutes to many hours). I found a single Gyre to be a bit ... lacking, as the water seemed to be always moving in the same direction. That's not the ocean, that's a river.
Wound up getting a second unit - I use the one on the right in laminar/turbulent mode with about a five-hour period to simulate the tides, and the one on the left in pulsed mode to simulate the surge of the waves. Over the change of the tides, the currents grower stronger on this end of the tank for a while, then switch to the opposite end . . .
~Bruce, hoping that helped clear things up
