Return lines?

[sacsalt]

Hi
would like to know what size hole should I drill for the return bulkhead?. I have the overflow bulkhead size at 1 1/2in.

 

[flukes]

I found this
"Pentair Aquatics 1 1/2" Threaded Bulkhead is threaded internally on the face end of the bulkhead (end facing down in photo). The opposite end is for slip fittings. Requires 2 3/8" hole."
I hope that this helps. Good luck!