Some reptiles have a salt gland near the nose to get rid of excess salts from their diet or water source. This causes crusty white buildup around the nose sometimes. It is NOT excess calcium (a common myth). The salts are primarily excess sodium or potassium. Do not change your calcium supplementation as the buildup is completely harmless and not a cause for concern. Check your water for sodium content and you may need to use distilled water. If the crusts bother you or your cham then gently wipe them away with a moist q-tip.