Yes, very much like a hot tub. The spa shares water, pump, filter, heater, and most likely an automation system with the pool. It may also have it's own pump for the jets, or it might use the pool pump for that as well. Normally you run the pool with the spa spilling over into the pool so the water in the spa is constantly replenished form the pool. Then when you want to soak you change the settings so the equipment is all connected to only the spa and use the pool heater to heat it up to temperature. When you are done, you go back to sharing water with the pool.