Need help with overflow.

Hi.

I'm about to attach the overflow in my diy AIO and need some advice so i get it right.

Dimensions.
Totall tank size 43x25x13" and sump messuring 25x9x13"

To calculate the lenght on the overflow i am using reef central calculator.
"Recommended minimum linear overflow size = 5 inches" for my 317 gph.

So what do thing about between 6-8" lenght instead, or is that just uneccessary?

(Tank specs)
http://ift.tt/1KMaqH7

Regards.

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