I won't go into how it is now as this is a temp test to see if I like the dual injectors. I'll explain how I had it and how it will be setup up tomorrow.
My whole system runs off basically one pump, Reeflo Barracuda (something like 4800 GPH). The reeflo which runs externally from my sump is ran into a T. One directs to the OceansMotion and the other runs to a Manifold. The Manifold is what runs my Skimmer, UV, Chiller, 2 floor retuns and water change valve. My Chiller, UV and Skimmer are all ran on one valve and strung together in that order. The floor returns has one valve that is also on a T. Change valve is on it's own and obviously only turned on when pump is off to drain the DT for water changes.
The Oceans Motion controls the other 4 returns on the tank.
Edit: Oh and forgot one valve for the refugium, which is set on a very light trickle.
Edit: Sorry, I see I didn't answer the questions lol
It is ran inside the sump under the tank.