Liquid replacement systems

A liquid replacement system is provided for introducing additives to an open recirculating system or a closed loop boiler water system in a controlled manner. The liquid replacement system comprises a make-up line and an additive system disposed therein. A make-up liquid enters into the make-up line where the additive system is structured to provide a controlled release of an additive to the make-up liquid, and the make-up liquid carries the additives into the open recirculating system or a closed loop boiler water system. The liquid replacement system allows for controlled release of additive components to the open recirculating system or the closed loop boiler water system, thereby delivering an effective concentration of additive components over an extended period.