Return line size

[SaltyVT]

I am running a 1.5" drain, if I run two 3/4" returns to a tee should the main line out be 1.5"???

[Urchinhead]

I believe it should be the size of the output pipe on the return pump. For example on a Mag 9.5 the return nozzle is 3/4" so your pipe size would be 3/4"