Di Resins come in two different colors, Blue or green. They will all change colors when they are depleted, usually to a rust or clear brownish color. As for DI in a bag, try to seal it air tight as they will go back if in contact with the air. Reason is that the air always has some kinda humidity and it contains water which the resin will absorb. If the bag or resin container is sealed. what ever moister is in that container will only stay in the sealed container.