Two long. I have a 1-2 inch sand bed. So if I mount the gyre vertical, the end comes above the water line--for sure when the return pumps are off and the gyre keeps going (like when I feed), but might also be above the water line when the returns are running.I'm still deciding on a powerhead I really like the look and dynamic use of the gyres. Did you ever think about just switching the Jump Gyre to a vertical position? I see how a horizontal position could get blocked by the rockwork, but a vertical position could just go around your walls.
I understand you can take off one side of the gyres and get a cap for it so that only one side runs, but then you're paying a lot for half a gyre.