Plumbing Question!

[Semper.Reefing]

This might be a dumb question but im really over thinking it.. Im building an external 2.5g refugium for my waterbox 20. I saw this build on youtube and its relatively cheap compared to ones you can buy from BRS.. I went ahead and bough .75" bulkheads. What size elbows and tubing will I require? .75" or .5"? I was also getting a ball valve for the intake. The return from the refugium to the tank will be gravity fed.

I understand a refugium isnt completely necessary for my tank.. I want to make a little mangrove display for my kitchen counter and am in need of a new project. Thank you in advance!

 

[lapin]

"bulk head size" means it requires that size pipe.