Tank disinfection with sodium hypochlorite

Hello everybody, I am trying to disinfect the water in a 500-L tank using sodium hypochlorite at 6 g/L concentration. I usually insert 125-150 ml of solution when the tank is full. My goal is to achieve a FRC concentration of 0.2-0.5 mg/L. Anyway, by checking  the FRC I found out a layering of the disinfectant solution proving bad mixing: 0.8 mg/L at the output placed at the bottom of the tank and 0 mg/L at the surface water in the tank. What could be a good way to have a homogeneous concentration of the solution? Inserting the solution at the water inlet or before filling the tank to increase turbulence? Any other ideas? Thank you for helping.