which size sump????

[Canadian Man]

Thanks guys.
Yes this is for the great barrier reef Kari

The sump will only be for having a place to run my skimmer, reactor and other doo dad's from. the sump will not be lit.

I am going to have a 75g tank(my current sump) has a separate lit refugium and a prop tank hooked up the the system as well.

cheers