mandolin open g

Looked on you tube ( but no luck ) for the correct open g tuning for the mandon as it seems to give a brilliant bluegrass sound . Can anyone tell me what the strings need to be tuned as ? Also - when I heard the stuff being played it seemed to be a lower tone  ( ie strings tuned looser ) - which I quite fancy as the strings on my mandolin are way to tight and are killing my fingers even though they are reasonably tough from guitar playing . thanks .