The difference between a spa and a pool is a matter of scale. I once owned a house with a poorly maintained pool. I spent hours and hours shocking it and filtering it until I realized that I would have to drain the damned thing. So I drained it, repaired some cracks and filled it up again. Then I had to get the pump motor overhauled, and while that was taking place, the water turned greenish.
After about $1000 in chemicals and other crap from a store laughingly called "Pinch A Penny", I got it to a swimmable state. Then along came Hurricane David, which shut up the electricity for two weeks and destroyed the screens surrounding the pool. I doubt that a spa could possibly be such a pain. Spas are small, and easier to clean and maintain.
I saw an ad in the Miami Herald about a special sale on spas. So I went to the showroom of the company that had the ad, and the salesman had never heard of anything that was in the ad, and was so utterly Joe Isuzu a character that I abandoned the entire idea of a spa. No matter what this creep sold me, I just knew it would be a mistake. No infomercial I have ever seen even came close.