big pump, little pump ?

[BlueAbyss]

Okay, one more thing. With a closed loop, you don't need to worry about head pressure, since the outlets and inlets are at the same level the head pressure is negligible. Even if the pump is 12 feet below the tank, you should get similar flow to a pump that is right below the tank, though there will be some loss because of the length of pipe running to and from the pump.

Count your turnover through the display, not the entire system's capacity. Your corals won't care if you have 30x turnover through the sump, unless they're in the sump.

[mark]

Comment about the Barracuda, it's loud. I personally can handle the Dart directly below the display, but no way could I see having a Barracuda.

Could consider having a CL Barracuda in the basement as well, leaving the 4way directly below the display.

As for turnover, like this Canreef thread for a idea of what others have.