A chemical control system for controlling the chemistry of a chemical solution having predetermined chemical constituents in a plating system, such as a NiFe plating system, employs a mix container for containing a plating solution and a hold container for containing a plating solution delivered from the mix container. A precision delivery arrangement delivers a precise predetermined quantum of a predetermined constituent of the plating solution to multiple mix containers and the hold containers. Transfer of plating solution between the mix and hold containers is effected by a transfer pump. Nitrogen gas that has been humidified with deionized water protects the plating solution from either acquiring water or becoming dehydrated, the humidified nitrogen gas being humidified to a predetermined relative humidity with respect to the temperature of the plating solution in the mix container. This is achieved by urging the nitrogen gas through a column that is at the same temperature as the plating solution. Precise delivery of the chemical constituents is achieved by a pneumatic pump arranged serially with an orifice and an inexpensive flow meter. The pneumatic pump is a positive displacement, double diaphragm pump.