How much flow through a 1" bulkhead

[SlavicSavage]

I was wondering how many gph a one inch bulkhead can handle? I was planning on drilling my reef ready 90 gallon on the back and have sealed up the holes on the bottom. However, part of why I was re-drilling it is because I wanted to be able to pure more flow from the system down to the sump and had heard a 1" bulkhead can only handle ~600gph depending on how its plumbed. A friend of mine told me he saw a tank that was running 1800gph through a 1" hole with a stockman. Can you do that?

[Kabuto]

I think I read the max was around ~850 but most people use 600.

Just looked at the RC calculator and it say 600gph requires a 1.01 in.