Need Help Designing the Plumbing for a 260g Tank

[b.branscombe]

After much thought, I've decided to replace my three sumpless tanks - one 220g and two 125g's - with a single 260g tank (96"Lx24"Wx26"H). I have numerous reasons for making the switch, and I won't bore you with them unless someone really wants to hear them. The tank will be drilled for overflows and return lines, with my current 220 becoming the sump.

This is where I need everyone's help. My previous tanks were sumpless, so I have a fairly small knowledge base about this type of thing. I want to install a center overflow instead of two corner ones, as I will be running a Tunze wavebox and extension, and would like to put them in the corners instead of the overflows.

I am looking for information regarding placement of both drain and return lines, as well as an appropriate diameter for the drains, what type of overflow I should utilize, and also wondering how many GPH through the sump I should be looking for.

Am I correct in thinking that most sumps are gravity fed from the tank? In my situation, the sump is going to be sitting in an adjacent room from the tank. From the bottom of the display tank to the top of the sump, there will only be a vertical change of 12", but the water will have to travel 11 feet horizontally. Is this doable, or will I need to use a pump?

Thank you.