Each Cinderella model tells you automatically, though the exact signal varies. The Comfort and Freedom display an “Empty Ash Container” message on the LCD screen with a beeping alert at 90 uses. At 120 uses, the same alert appears but the toilet won’t let you start another cycle until the ash container has been physically removed and reinserted. The Premium works the same way, plus its display shows a running flush counter so you can see exactly how many uses have accumulated since the container was last emptied. The Travel model doesn’t have an LCD display, so it uses beeping along with a sequence of flashing LED lights to signal different messages, like when to empty the ash container.