Quote Originally Posted by Polizei View Post
I think what' he's talking about is a sharp 90° bend to angle the output of the first pump down into the inlet of the second pump.
Exactly, bends right before entering the pump impeller is bad. The gveneral rule of thumb is to provide at least 4x the diameter of straight tubing entering the impeller. This supposedly helps straighten the flow and allow an even loading of the impeller.

While bends are relatively insignificant in the loop, they are fairly critical right at the pump itself especially at the inlet side.

Thanks for the testing skinnee, will be nice to get some science behind how well these work. I was always skeptical compared to two separated tops, but now well know..