Help rerun pipe size

[Tcm99]

Hey I am building a 45 gallon cube. I drilled it for a eshopps prodigy over flow. I want to have two returns. 1 on each side of the over flow. I am wondering what size pipe is should run on the return 3/4 or 1/2. If you guys have a similar set up post pics please u need a lot of ideas

 

[mfinn]

My first thought was dual 1/2" return lines should be more than good for a 45 gallon tank.
Maybe 3/4" or 1" coming out of the pump ( whatever the pump is) and then split into dual 1/2" lines, somewhere it's convenient.