When I bought my Hot Springs Sovereign about 20 years ago, I went to my doctor and told her that I have always experienced lower back pain, and did she think hydrotherapy would help. I even had the brochure, but didn't need to show it to her. She said, it would help, so I asked her to write a prescription as if I had a doctor's prescription, I didn't have to pay for Florida sales tax. (The Hot Springs retailer told me that hint.)
I would suggest you check to see if that is still in effect as that will save you hundreds of dollars.