Return Pump plumbing size!>!!??!?!

[BBoley24]

I am going to be running 2 return pumps. A Mag9.5 and Mag1200. One will be hooked up to a SQWD. Now I have heard that your piping should be double the size of the exhaust on the pump. Is this true? What would you recommend on my 140gRR?

[sjm817]

Yes. 2x outlet size which is 1.5". The SCWD will really kill the flow. It cut my Mag9 flow in 1/2.