Return plumbing question

[sgallagher7]

Im close to plumbing my tank and want to do it right. I plan on using flex pvc to reduce head loss. The question is my eheim return is a 3/4 as well as the return in the overflow. Should I use a coupling to go from 3/4 to 1" and then a reducer at the overflow return back to 3/4"?

 

[EdKruzel]

It's best to keep it all the same diameter.

 

[sgallagher7]

Thanks. Just want to do this right the first time.