I have a HydroSpa Lexxus III, installed Jan 05 and have had a great deal of trouble with the heaters open circuiting. HydroSpa has been of no use other than to keep sending replacement heaters and asking me to install them because they cannot get a service tech to my location.
The unit uses a Balboa HS200 controller with integral heater tube.
I appear to have solved the problem by replacing the controller but HydroSpa would not supply one under warranty and I had to buy a replacement myself.

Warning - do not buy a HydroSpa unless you can service it yourself. And pay for it.

Out of curiousity, what size element have you been using? Balboa controls generally use a 4Kw element. Running a higher wattage can do one of two things if your system isn't designed for it... burn out the heater relays on the circuit board, and shorten the lifespan of the element due to inadequate water flow.

The HS200 controller uses a 5.5kw heater element. A 4.5 kw is available as a replacement. Next time I replace it will be the lower wattage