The air dryer is for use with any Aqua Medic Ozone Generators. Ozone output can decrease dramatically if the supply air is very humid. Ozone Booster should be used to dry the air, particularly if a protein skimmer is supplied with ozone using the humid air present in the aquarium cabinet. In some circumstances ozone production can be almost doubled. The unit utilises silicagel as the drying component. The silicagel should be changed as soon as the indicator beads change their colour from orange to blue.