Ok, Need input on Flow direction

Ok, Im setting up my new WC system.... This will be a external kit, as I dont have room for the heatercore. Here is what I have to work with.

77' Bonivelle Heatercore
Ehiem 1250 pump
Danger Den 5 1/2 Resivor
Danger Den TDX waterblock.

I want to know the optimal flow direction, and what should go where in this system. I havent installed it yet, as I am working on a external setup in a spare case I have.

Thanks for the input guys...

My personal experience is this...it doesn't matter. I've found that any differences that might exist appear to be too small to notice.

I would agree with graystar except I think it is a good idea to keep the res right befor the pump if possible to ensure the inlet has water all the time which would mainly only be durring fillup and bleeding.

ok.. sounds good, now, Im a little confused on how to run it, my other WC kit, Thermaltake AqariousII, Im not using the res on it, and on this new setup, Im not sure where to run the tubing.. on the Ehiem 1250, I would assume the flow direction is up, but I dont really know what direction I should run the tubing...