FreshWater Vanishing Act XL is an easy way to reduce calcium levels in larger spas and swim spas during initial start-up or refill, or when calcium levels are unusually high and a regular size Vanishing Act won't be enough. High calcium levels reduce the lifespan of your hot tub and sanitizing system.
For most large hot tubs, you can simply place the Vanishing Act XL pillow in your spa and wait 24 hours for the calcium level to decrease.