
Stuff growing on filter in rental hot tub— bad stuff or just gross stuff?
I’m at a vacation rental with a hot tub. I know nothing about pool maintenance and the owner is adamant that “if there’s no mildew and the water is clear, it’s fine.” But these soft, brown growths are attached to the filter, and maybe also something calcified on the side? I kicked this by accident and some of the brown bits detached, then some reattached. They don’t float.
So is this stuff gross but harmless, or bad? If it’s bad, is it like flesh-eating amoeba bad?