If you knew what lives in a hot tub, regardless of how clean the users you would never go near one. While folks think they control what lives in there, they are sadly mistaken. And for heaven’s sake never, ever use a hotel hot tub.
One of my biggest customers was a hotel chain. They had a legionnaires outbreak. I tracked it to the hot tub. And believe me, the chlorinated that thing to a fair thee well.
Critters adapt and become quite happy breeding in chlorinated water. That’s why in industrial water systems we change biocides routinely.