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

[MikeInToronto]

Originally Posted by kien

All you need are two drains to run a herbie as already mentioned. One for the main and one for the emergency. It looks like you have a third in your overflow box? I'd either cap that off and don't use it, or 'T' two of them together as your main and use the third as an emergency. Another option is to use the third as a second emergency which I think you were planning but that is a little overkill. Nothing wrong with that though I guess. If your drains are 1.5" it will be very hard to overflow a wide open 1.5" drain unless your return pump is rated for something insane like 3000gph (don't forget about the loss of flow due to elbow, head and such), which it probably won't because then you're pushing way too much water through your sump in my opinion

He has 3 because he's planning a Beananimal, and he has more than enough room to do it. I wouldn't sacrifice the extra security if I didn't have to, even if I thought it was redundant.