Inlet vs outlet size

[IRL]

Hi
On the DIY 55 gallon drum filter I have read that the outlet should be twice the size of the inlet. If I have a 3/4 inlet, should I have a 1 1/2 outlet, or should I still have a 2" outlet like most people i have seen? Or, should I just switch to a 1" inlet?
Thanks

 

[addy1]

Either would work, the bigger the piping the less friction you have even on the inlet.

 

[fishin4cars]

either way would work fine, but like Addy said, if you go bigger there is less friction and better flow rates once there starts to get build-up inside the pipes. On the bottom drain, be sure and go 2" you do want to get as good a flush as possible at the bottom of the 55 gallon barrel.