This is nearly the same as organic or inorganic, but a distinction needs to be made for films on surfaces-biofilms versus scale deposits. Usually the two are mutually exclusive, because the high temperatures that often lead to scale formation usually kills micro-organisms. However, commercial ice makers of the recirculating cascade or spray types are susceptible to both, simultaneously. Scale develops because the minerals in the water become progressively more concentrated as the ice grows, but psychrophilic (cold-loving) bacteria and molds also form complex slimes that require regular clean-up.