Continuing MitchM's post and Stir Crazy's request here is another option for mass movement.
Below is the simple line drawing for a pumped surge device.
This pic shows the 4 sequences and how the direction of the tank would be affected, please npte that these are views from above, red are C/L feeds to pump and blue are C/L returns from the OM unit.
In Stir Crazy's situation the outlets could be split to get the laminar flow he desires,