Hot tub, lol! cheap sheek, middle class stew pot, filled with fecal matter and dead skin! As a plumber I know how nasty hot tubs are ! Either you are stewing in fecal matter of your own and any guest who has dropped by to take a leak or scrub thier root out and left it just for you or the chemicals you need to disinfect it enough to kill the bacteria makes it little more than toxic cocktail! lol! yes, mntnn of sludge, enjoy your hot tub, a just reward for an alliance with ignorance!