what are they set at now? Roger suggested interval 2 to me, and originally I balked, because I wanted some back and forth. But on INT 2, there is always good turbulent flow, and when the pulse kicks, you still get the back and forth, just not as extreme (especially with a 4 foot tank like a 120). It also reduces cleaning frequency. I have my stream in the back corners angled toward the opposite front corner, INT 2, with pulse at 6 seconds.