HTH Pool Care Green to Blue Advanced Shock System 2 Step Solution Green to Blue 1 Kit The HTH® Super Green to Blue Advanced Shock is a 2-part system. Pack I shocks your pool with a boost of chlorine helping you fend off bacteria. Pack II is a powerful flocculant that drops particles to the bottom of the pool for easy vacuuming. Both packs work together to create beautiful crystal clear pool water within 24 hours. How To Use HTH® Green To Blue Advanced Shock System: Simply follow the on-pack instructions for both Pack I and Pack II. Pack I is the Cal Hypo Shock treatment and Pack II is a flocculant that drops dead particles to the bottom of the pool for easy vacuuming.