A tank on a firefighting aircraft initially is loaded with water. A polymer gel emulsion vessel is provided but gel emulsion is not activated and mixed with water in the tank until such polymer gel preparation is initiated by an operator. When initiated, a pump pulls water from the tank and returns water back to the tank with a dose of gel emulsion supplied therein. Double elbows and/or the pump impeller fully activates the polymer gel. The activated polymer gel is mixed within the tank by one of a variety of systems including sparging with air, routing of return water from the pump through nozzles and providing a baffle for generating circulatory mixing flow within the tank, or utilizing a mixer element which moves dynamically within the tank. Hydrodynamic forces associated with the aircraft passing over a body of water can power dosing of the water with polymer gel emulsion.