500g is a little over a pound so that would be way too much to add. For a recent porter that I made I used .25 lbs (115g) so that might be the most you'd want to toss in there.
Keg 1: Calypso, Azacca, & Mosaic IIPA
Keg 2: Pigskin Brown
Keg 3: Kolsch Pale Ale
Keg 4: ESB