Planning to upgrade our 90 gallon to a 120 at some point so doing some planning research , the 120 is what I should have started with to begin with but that's another story. The question i have is internal single center overflow box , or a external overflow. What's everyone's opinions. The tank I am looking at has both options with a 3 hole internal box I would run bean animal and then have it drilled for 2 returns. Or should I run the external ghost overflow box configured the same way. What's everyone's thoughts on this ? Is it just personal preference or what is the real advantage other than space saving and looks. Thanks in advance