Drilled Hole Size And Connectors For External Filter

[mjbarnard]

I am getting my new tank drilled so that the filter(s) can have their inflow and outflow directly through the base of the tank from the cabinet below.

The aquarium company wants to know what size holes I want.

I will probably use Eheim filter, model not yet decided. My questions are ;

1) Where can I find the hose size for the input and output of any Eheim filter?

2) What size drilled hole should I specify, for a given filter hose size?

3) What bulkheads and connectors will I need to plumb in the filter in this way?

Thanks
Matthew