Drain placement - Back of tank or Bottom?

[VLDesign]

Drain placement - Back of tank or Bottom?
Is there a performance difference between a drain being in the bottom of an overflow box or in the back of the same box?

My problem is the bottom of my new tank is 18" from the floor, and the sump is 24" tall in the next room. I can either use the standard 2 x 1.5" drains and let them go up 6" before draining or put the bulkhead in the back of the overflow and have it all drain down hill.

Im trying to not lose any performance with the drains.

Reason I ask is I have a 40 gallon tank with the drain in the back towards the top and it doesn't drain nearly as quick as another 40 with the drain on the bottom and both have 1" pipe.
Hobby Experience: 7 years Fish only

 

[saltydog_1]

i have both but they both take water from the surface i like the drain in the back more though i just sleep a little better knowing if there is a plumbing problem my tank wont be emptied onto the floor when i wake up in the morning

 

[gomezladdams]

I like the back too for the same reason

 

[BIGgourami]

the one with the drain at the top, is it at the waterline, or below?

 

[VLDesign]

Below

 

[BIGgourami]

back.