How to plumb returns?

[Kzang]

I got 125g aqueon reef ready with dual overflows. Not sure how I should mount the loc returns. Both on outside, or both inside?

I'm thinking both on outside and put a mp10 in middle back focusing on rockwork to have flow in the back between the two overflows.

I have or will have two mp40s pointed on the ends at each other

 

[ndrwater]

Definitely on the outside. You will need the appropriate sized bulkhead to thread the loc line into.
That said, th gasket on the bulkhead goes on the tank side with the nut on the inside of the overflow