I am planning a new tank 96"x30"x30".  I am currently thinking about running a Mag 36 or similar size for the return and one 3000 gph closed loop.  I was also thinking of 4x6100 plus controller for more circulation.  The units would be in the back corners and the middle of the sides.  Is that a good placement?  Would that be enough circulation for a varied tank?  Should I have two of the units on at all times with the other two alternating? What would your suggestion be????????