180 gallon plumbing question

[Sean Norman]

Picked up a used and well cared for 180. It was a custom build, 72 long, 20 wide and 29 high.
It has two installed overflow boxes mid tank on the back wall.
They each have two bulkhead holes in them, a 3/4 and 1 inch.
My other tank is a 112 with a primary, secondary and emergency drain and return line.

Wondering.. just plumb two. 1 inch durso drains and two 3/4 return lines? Or could I get away with one 3/4 return line and use the other as an emergency?

 

[CHIEF_OF_THE_REEF]

I have seen that before, and I have also seen the returns come over the top on the out side of the tank before.

 

[Jmcg89]

I have seen that before, and I have also seen the returns come over the top on the out side of the tank before.

That's how I did my 180 herbie style in the over flows and one return line in the back middle outside