Ok I have the jist of what your saying.So any size overflow will work.2 things I was wondering.The water level has to be a certain highth so it slowly goes in overflow,but how do you set that point or is it trial and error.My second thought is can I have a small pump run outta my wet dry area into refuge,so in essence water goes into wet dry 2 pumps out.1 back to tank and one to refuge or that a disisater waiting to happen.It sounds like i'm babling,but I understand what you mean now,just fine tuning right my brain right now.