Abstract: A fluid injection system for dispensing a solution into a fluid flow in a flow line, the fluid injection system including a storage tank having a product to be dispensed therein. The system includes a connector for connection to a fluid flow line. The connector has an outlet port for diverting fluid from the flow line into the tank, an inlet port for returning a mixture of fluid and/or product back into the fluid flow line, and a restrictor provided between the inlet and outlet ports. The system includes an inlet dip tube and an outlet dip tube provided inside the tank and a mixing chamber connected between the inlet dip tube and the outlet dip tube. The mixing chamber is configure to mix the fluid with the product to create a fluid/product mixture, wherein the fluid/product mixture is injected back into the fluid flow line via the inlet port.