ReefArtist...82mm would be perfect, but 85 works well with the large gasket that comes with schedule 80 bulkheads.
rsxs...Diane informed me that I will be putting hardwood flooring in about 600 sq. ft. of our house starting this month, so I'm thinking freshwater testing next month. I still have to finish some plumbing and the skimmer pumps. Then there's the lighting. If all goes well with the water test, I'll cycle the quarantine (thank you) and start making salt water for the 390!!!
CaveManOhio...I had a quick connect fitting added for the cup. The skimmer is just over 38 inches, with about 1.5 inches over it. Only requires 0.5 inch for removal. You have a sharp eye!!! Small amount of plumbing compared to yours.