newbie piping questions - what size return - what size overflow?

[mark]

check out a Herbie, just needs 2 holes and you'll find quieter than a Durso, Stockman or Hofer.

As for as pipe size, I've got a 1" return and 2x2" drains, can easily handle 2000gph so hindsight could have gone smaller. If you do go a Herbie or Bean, look at Bean's calculator, seems you get a lot of water through a relatively small pipe on a full siphon.