I would suggest (and I am far from an expert) a two way split from the return pump to direct flow from the center top to the corners. Unless you have a need for high flow this might be enough. You can even get fancy with the mag 5 and run it into a SCWD (Squid) and then into two seperate returns in the tank. That will provide alternating current. I use something like this with my Closed loop.
http://www.melevsreef.com/closedloop.html
For instructions on the closed loop.
In your situation you would simply build the SCWD to return portion. No need to build the intake portion.
HTH
George