Overflow advice

[golf nut]

Originally Posted by Kalifornia

Hey fellow reefers

Need some input to help my buddy out with his 90 Gallon cube tank.
It's drilled in the center and he is building an overflow there , to ensure the ABS 8" pipe adhere's to the glass what is his best way of doing so ?

Thanks

What size bulkhead has he drilled for? does he have a sump return bulkhead near by also?