Why do the Dri-Z-Air crystals get hard?
The Dri-Z-Air crystals are calcium chloride, which is a non-toxic inorganic salt product. As with table salt, when they collect moisture, they harden. Dri-Z-Air crystals are like a moisture-absorbing-magnet as it pulls the moisture from the air. When the crystals have grabbed all the moisture they can hold, the liquid will begin filling the bottom of the unit and the crystals will dissolve.