Returns

[John Michael]

what size whole is best to drill for the return to your tank? Tank size is about 75.
Gonna dril the overflow that’s gonna be 1inch but what should the returns be?

 

[RobZilla04]

In most to all cases those holes are fitted with a bulkhead. Those can vary in size, but the typical return line size is 3/4".

The first three top sellers would obviously be a good choice:

https://www.bulkreefsupply.com/pumps-plumbing/plumbing/bulkheads.html

 

[garbled]

If you are already drilling a 1", just do 1" for the return. Even if you plan to run a 3/4" locline inside the aquarium, having 1" pipe from the pump to the bulkhead will at least reduce friction losses a little bit. You can just put a reducer on the loc-line fitting.

Unless your pump outputs are 3/4, then I guess run 3/4 for ease.

 

[Cjud7982]

If you are already drilling a 1", just do 1" for the return. Even if you plan to run a 3/4" locline inside the aquarium, having 1" pipe from the pump to the bulkhead will at least reduce friction losses a little bit. You can just put a reducer on the loc-line fitting.

This is exactly what I do. Most holes I've ever drilled are going to be for a 1 inch bulkead. 1" returns are great and as mentioned reduce to 3/4. I always use threaded bulkheads for this so I can easily swap out something I don't like.