In The Swim Sparkle Plus Pool Water Clarifier - 6 Ounce Cube One 6 ounce Sparkle Plus cube Sparkle Plus cubes clear cloudy water and aid in the removal of phosphates and cloudy water Even when totally dissolved, the active ingredients continue to work for up to 4 weeks Each Sparkle Plus cube treats up to 30,000 gallons of pool water Not for use in a DE or Cartridge filters