I don't know if this will be helpful or more confusing, but here goes.
This is what I have done to get all my equipment and sump in the basement (and yes it makes the display tank very clean and quiet this way).
I've labeled all sorts of stuff in the image to try and help explain what's going on because there is a lot of PVC!!! It's really pretty simple though. Water from the overflows on the display tank comes in via the 1 1/2" pipe that dumps into the filter box on the left side of the sump (it's works like a sock and allows me to run various media there with lots of flow over it). There are no baffles on this setup as the return pump is on the far right side and it's far enough away from the inlet and skimmer that no bubbles make it over there. The return goes back to the tank in 3/4" pipe which then splits into two 1/2" returns at the display tank. The fuge sits right on top of the sump. It's fed by a little pump (modified
power head actually) that pumps water into the left side via 1/2" pipe. The fuge is drilled on the right side and has a 1" overflow which dumps out right by the return pump (I figured maybe more critters would get to the display this way).
You see quite a bit of additional stuff/plumbing in the photo since I have a kalk doser, auto topoff, and PVC DIY skimmer.
Anyway here is the photo so you can try to make sense out of it all:
You can find a some more info on how the topside (IE. display tank) is plumbed in my 125 build thread:
http://www.thereeftank.com/forums/f6...ighlight=build
Good luck figuring it all out...shout if I can help in any way.