Originally Posted by waffle
I've decided to go with a small overflow box on the inside of the dt about 2"x16"x7", I also plan to have a ledge extending the length of the back of the tank similar to a coast to coast but instead of a box it will just be a signal glass strip siliconed on a angle feeding into the internal box for the external I plan to modify a 5 gallon with a ba overflow in it ...the question is how big should the hole(s) be connecting the internal and external?
If I followed that correctly, your asking how large a hole, and connecting pipe work for the drain should be. It depends on your tank size, and pump flow. Your can google that information easily.