over flow help?

Hello,
I would like to build my own over flows for my new tank.  I just got a all glass, 120 48 x 25 i think.  i want to order the stuff to build them from bulk reef but im not sure the size of the pipe and stuff that i would need does anyone have any idea's?
Thank you,

 

do you know what gph you will be using? what kind of overflow are you talking h.o.b or built in .

 

My tank is drilled with 1 1/2 in holes . i purchased the piping from home depot and the glass from ace hardware

 

eyah the tank came drilled and that was another question i would have is what pump to get as a return

 

IMO i would go with around 1200 gph ive read alot of ppl go with the 10x rule but its really personal preference there are atvantages to both slow and fast

 

so mag 12 or something like that then i would think

 

Yeah ive heard good things about mag pumps.