For example, the housings can be made of other shapes, such as rectangular, lid 42 can be omitted, the heater can be omitted or made separate, passageway 71 can be omitted, outside housing 14 can be replaced by suitable channels or troughs, the conditioner can be made integral with the tank or its top, the disposable cartridge can have a nonsealed lid so as to make it a permanent housing, in which