All ozonators are NOT alike. I can't really tell you which is best or necessarily explain the features of each but to some degree you get what you pay for. At the same time, you don't necessarily need the best high output ozonator with a smaller spa but IMO I wouldn't go gett a UV unit or a cheapo CD unit just to save $$ and have something that isn't too effective. As much as I am an ozone backer, with some of these $100 units I wonder if you're not better off going ozone free and just use more chlorine.