4 6100's may be overkill, I would try on in each back corner using Interval 2 mode and aim the pumps so they hit the front pane 4 ft away. Set the Interval at about 6hrs and pulse from 30-100% every 3 seconds.
Another option with 4 pumps would be to use sequence mode. Place the first pump in a back corner and then place each additional pump 12-18" away on the back wall. Aim them so they are all facing parallel to each other with the last one hitting the nearest front corner. You can stagger them in height, they will come on one after the other with all four running at the end of the sequence creating a surge.