I have read a few different ways people on this site go about cleaning their misting system and nozzle. The things I read was to pull the system out of the cage and run a few cycles of a vinegar/water mixture or lemon juice/water mixture. Other said that soaking the nozzle in CLR over night and throughly washing it after soaking works well. To help prevent this problem in the future use a RO system to filter your water and remove the impurities.