As a reference for the last picture above, the bottom 1 1/2" line feeds the Vortec that supports the frag system. That vortec feeds the two frag tanks, two reactors, and the skimmer. It might be a lot to ask of a single pump but I'm not planning on running a huge amount of water through the frag tanks, just a lot of internal circulation for each tank.
The second line from the bottom is the feed line that comes from the main system. It also won't run an enormous amount of flow through the sump, just enough to keep the frag system water well mixed with the main.
The top line is the return from the skimmer.