propagation system for sps.

[djbh]

Hi all,
Am starting a prop system I have a 55,33,25.The 33 and the 25 are well established (3 years) with aragamax oolite.Live-rock and all.I want to plumb the 55 into both.Making it a 3 part system.
Is it better for the 33 and 25 to overflow into the 55 or vice versa.
Should I leave the prop tank bare bottom and make racks for elevation of SPS.

Anyone have pics of their systems to start me off?
Thanks
Dan