You could run one side to side and then one near the top to "roll" the water column forward. This should drive any CO2 enriched water forwards and down into the open areas to help distribute it. The tough part will be making sure it gets through the plants.
An alternative could be to aim it down and try and get the CO2 down and into the thicker growth in the back first. The side to side action of the other bar just helps to mix the intake water a bit to help even everything out with nutrients and such.