Bulkhead for deep blue 30g tank

[DazAquariums]

Hello! I have a deepblue 24x24x12 frag reef ready tank. I need to get a bulkhead for the return. I learned the hard way 1 inch is to large. I see no documentation for it online. Anyone know what size the return is?

 

[ca1ore]

Return on my deep blue is 3/4” bulkhead.