Help with sump..please

[aquashelle]

Alright, forewarning, I'm a complete noob when it comes to sump..so I'll try my best to get everythign correct.

We have a 155gal tank, that is not drilled.
I recentally purchased a pm skimmer, that came with a mag 12. (1200gph)
The skimmer is an Es100, along with a WC410 extra collection cup.
(Link to skimmer)
http://www.precisionmarine.com/html/es100.html
I'm going to have to purchase an overflow, and I'm looking to build a sump.
Due to the size of the tank, and rate of the pump, how big of a sump could I get away with? I'm looking to do that smallest possible, and I am in desperate need of help as far as how far apart the baffles go, etc etc ETC.
Any help is GREATLY appreciated!!

 

[i<3reefs]

At that size I wouldn't go smaller than 20 gallon, but if you could go 40 gallon you would be really happy long term. With the extra room you would have the option of running a phosphate reactor and/or carbon.