Why is it uncommon to extend the sump to plumb straight down?

[NancyFish]

Just the normal fitting size. The street allows you to just have one glue joint and no pipe required.

Thank you, you’ve been super helpful!

 

[VintageReefer]

My 75 has an internal overflow and I positioned the sump so my drains are straight. I use smooth flex tubing for the return. Its nearly vertical, just a very gradual slight curve.