Systems, devices, and methods are presented for optimizing the formation of gas nanobubbles in a disinfecting solution. In an example system for treating contaminated water, a centrifugal pump draws the water from a reservoir and circulates the water in and through a circuit of elements including a mixing chamber in the pump, a pressure vessel, a backflow valve, a Venturi injector, and a pair of nozzles immersed in the reservoir. The system injects ozone-rich gas into the fluid to produce an aqueous solution containing a volume of gas nanobubbles. The nozzles release the gas nanobubbles into the reservoir, creating highly reactive compounds that destroy organic compounds and other contaminants in the water.