Use our Sodium Di-Chlor Chlorine Granular to kill visible algae blooms and invisible bacteria, which could cause illness to swimmers. Your daily chlorination of the pool will kill most bacteria and other contaminants. To be sure that the water is completely sanitary, it is best to super chlorinate by shocking the pool every few weeks. Doing this also allows you to oxidize everything in the water, especially the various contaminants that may exist in the water.