A spa system featuring an immersion tank for holding a therapeutic liquid, the immersion tank may feature multiple sectors, a hot reservoir, a cold reservoir, and a mixer reservoir. The mixer reservoir is fluidly connected to each the hot reservoir, the cold reservoir, and the immersion tank via pipes. The hot reservoir has a heating element, and the cold reservoir has a cooling element. Pipes and pumps connect the immersion tank to the mixer reservoir and to the hot and cold reservoirs and the hot and cold reservoirs to the mixer reservoir. Temperature sensors are disposed in the immersion tank and the mixer reservoir. A control unit having a microprocessor functions to change temperature of the therapeutic liquid in the immersion tank by activating various pumps such that the temperature of the immersion tank matches a pre-programmed temperature.