Reef Dynamics has a replacement pump, SP3-c for $180, and ASM has theirs for the G-4 for $98. Both are modified Sedra 5000 pumps. I'm wondering what the big differences are in the mods? The venturi size? Pinwheel design? Obviously the SP3 is made for the euro-reef body so I assume that the mods are tweaked for it but is it that much of a difference?

