The spa has two drains, and one caretaker valve in the floor to circulate chlorinated water to the spa when the pool is the primary use. It has four jets that are specific to the spa when that is the primary use. The valves for the system can be turned so that the sole (I think) intake and return are for the spa, the pool, or both. Whether turning the valves so that the sole drain and return is through the spa jets constitutes a "total isolation," I don't know.
I'm in NY and obviously the swimming season is over.