Need help on drilled return placement

[AJ192]

Hello everyone I hope your having a good day.

I am planning to drill 2 3/4 inch return line in my 60” long tank. But I need help on placement. I’ve read many places that you need to drill right below the waterline to prevent too much back flow from going into the sump and flooding it. But I can’t figure out how far in from the side I should go. What are your thoughts?

 

[lapin]

I use the the hole diameter as a guide as to how far from the edges or each other.