Return lines

[sarimus]

Hi
Our tanks sump inlet is up top, do we just plumb the return lines to shoot the water across the surface and rely on wave makers to circulate the tank water.

 

[ENDUexe]

Sounds about right.
If the return nozzles are below the surface, you are all good. Otherwise, use some loc-line so the inlets are submerged or they will splutter and splash everywhere.
You'll struggle getting proper flow with just your returns without the addition of a bunch of noise. Wave makers are the way to go.