http://www.intheswim.com/Pool-Chemicals ... MiraClear/
Billed as a clarifier - what is it really?
"#Place the shell shaped gel cube in your pump basket and start clearing up even the cloudiest water conditions immediately! The gel cube will dissolve within 24 hours while your pump is running.
Increases the power and efficiency of your sand filter by removing the microscopic solids and stain-causing metals that are not normally filterable.
No mess, hassle, or measuring!
Treats up to 30,000 gallons. Lasts up to 30 days."