They’re not called hot tubs anymore…they’re called spas. This article in The Times by Denny Lee has some photos of beautiful tubs along with a history of the rise, fall, and rise again of the, um, spa. The big deal is why they no longer pose a health risk or stink with chemicals. Short answer: new water ionizers clean just like air ionizers, (whatever those are.) Perhaps you can get your Super to install one on the roof….