jackrae:
Won't the convection currents set up by the 6kW heater produce enough stirring action for you. Alternatively have you thought about simplifying the problem by using a dip tube and "bubbling" air through the water. Yes, that doesn't answer your question but it might be a solution to your problem.
Yes the 6 kW element will agitate the water, but not enough from my research, I am running 50 ft of 1/2 tubing for heat exchange coil and need something a little more aggressive in agitating the water.
I have also thought about air bubbles as well, but I am leary that I may end up with super or overly oxygenated water. I intend to use this liquid at a later time and it may effect the end product if I have overly oxygenated water in the procress. I think I might be a little to picky on this one and may have to test it further though. Thanks for the idea!! And if you haven't guessed already I am home brewer and I am designing a new system with all the bells and whistles.