Setting Up Refugium & Sump ** NEED ADVICE**

[ZachAttack]

OK, so I think I understand this a bit better. So, with the lip type that you are planning on, does the back wall of your tank need to be shorter than the other walls so that it will flow over that into the overflow?? I`m confused how you get that to drain into the overflow without drilling. Also, I took a closer look at the refugium that he has, and am confused as to how that part fills, because the wall is higher than the sump section.