I get asked frequently if I sell salt systems in hot tubs. The answer is no. Although it makes perfectly good sense to sanitize your pool (large body of water and cold vs hot water) with a salt system the cost to put these in hot tubs and the difficulty changing out the cell makes it less attractive in hot tubs. Not to mention most clients really don’t understand that you do need to change the cell every 500 hrs of usage or so.
In most cases I would recommend you consider a UV (ultraviolet light) to assist you in your sanitation of your hot tub. Many countries use UV lighting to kill bacteria in their drinking water. In fact, most people in Canada who are on a well system use UV light to kill bacteria. These units make good sense in a hot tub.
So when you are thinking salt, think yes for a pool application and no for hot tubs. Ask questions, do your research, ask a professional as this allows you to make good buying decisions.