Red sea max e170 sump plumbing help


Reefing newb
has anyone found pipes / fittings to fit the red sea max e170 bulkhead? Ive found info on the reefer but dont know if its the same. have all the acrylic to build my sump / refugium but really need to get the plumbing squared away. ive heard the use 32 mm pipe but when measuring the plug in bulkhead looks closer to 1.75" not 1.25 (32mm) any help greatly appreciated, dont want to drain the bulkhead only to find out i need different parts. thanks for any help

heres my current sketch of sump/refugium any info appreciated

just realized i put skimmer before refugium. updated pic