I mount my spraybars on the side glass, so that it pushes the water across the length of the tank, not into the glass directly in front of it. With the narrowness of the 55 gallon, it takes a little creativity but it's possible - I did it. I also put the intake in the same corner of the tank as the spraybar. I saw a computational fluid dynamics model that demonstrated that that was the best placement of the intake.
I would still get a powerhead though, to put on the opposite side glass, in the back, 2/3 up from the bottom. That will give you the best circulation.
I would still get a powerhead though, to put on the opposite side glass, in the back, 2/3 up from the bottom. That will give you the best circulation.