Overflow dimensions

[Doug]

If i were to have one overflow, what would be the best dimensions for the overflow if i were to run the return as well as a durso standpipe ?
3" by 9" ? 4" x 8" (the overflow calculator on reefcentral says that i need 9inch linear overflow length for 600gph..but i dont know if that value includes the teeth or just the gaps)

I'm most likely running a 1 inch bulkheads (so 600gph) as my drain, and for my return i'd need a 3/4" bulkhead ..so taht means my largest drilled hole should be 1 3/4" inch ?

I like the two overflows for the reasons mentioned. My larger tanks had two. They were 6in. sq. inside measure. I dont like the smaller holes though. Both mine had 1.25in. drains, meaning the drilled holes were about 1.75 in. or so, depending on bulkheads.

However, on my 180 cube, I went with a single sq. corner overflow, again about 7in. sq. All these used eggcrate teeth by the way. This time I had a 2in. + hole drilled that allowed for a 1.5in. drain. I really liked that set up and the larger drain allowed for a pump size increase or not.

Just my opinion but I dont like 1in. drains. If doing so, then for sure two overflows is the way to go.
Help please, and thanks in advance. -- I asked 3 times on reefcentral, and my threads get buried in no time! Might as well try here as well!