If the nozzle turns green, this means bad maintenance of the device, i.e. non-sterilization of the nozzle.
We put the nozzle in vinegar in order to break down any salts which have been concentrated and in order to clean it we pour alcohol on the nozzle and inside it in order to sterilize it and then once a week we pour alcohol on the rim and in the nozzle in order to avoid such problems (as it happens in the rivers where water runs on stone and turns green, it happens because of the aerobic microorganisms which are good microorganisms and create the green color).
