Floaters dispense chemicals into the spa water 24/7, whether they’re needed or not. When the spa is closed with the jets off, the floater will stay in one location in the spa, spilling chemicals onto the horizontal surfaces immediately below it. Because the tablet does not dissolve evenly, those bits will etch and pit the plastic shell surface, leaving a rough surface that will not be comfortable to sit on and can damage swimsuits. These rough patches cannot be sanded or removed from the shell. View Hot Spring water care products