overflow sump HELP

[eli@fijireefrock.com]

i understand that you have 2 holes in your over flow box.(i don't see why one is smaller than the other)
if that is the case i would use the smaller one as an emergency drain to the sump in a Herby setup.

[intarsiabox]

The smaller of the two holes is usually for the return line from your pump back into the tank. You, of course, do not have to use it for the return line and an emergency overflow is also a good use of it.