Aromatherapy can be something as simple as cookies baking in the oven, and something as powerful as getting a person who will not eat to eat. There are lots of things that aromatherapy can do. In a hot tub it is just meant to relax you and make it a more wonderful experience. Try adding a few whole bay leaves to the water, I know that sounds a little crackers, but an entire perfume industry grew up over the smell of Bay Leaves and has existed for decades....it is called Bay Rum.