Abstract: Embodiments of the invention provide a stationary fire fighting system for retrofitting into a structure. The system can include a flowmeter in fluid communication with a water line in the structure. The flowmeter can generate a flow rate signal. The system can include a controller connected to the flowmeter and a proportioner pump connected to the controller. The system can include an additive supply tank in fluid communication with the proportioner pump. The controller can operate the proportioner pump based on the flow rate signal to provide additive from the additive supply tank to the water line to create a solution. The system can include at least one sprinkler head to distribute the solution within the structure.