PAK® 27 Algaecide is approved for use as an algaecide by the U.S. Environmental Protection Agency (EPA). Depending on state regulations, it may be considered a Restricted Use Pesticide. PAK® 27 is also approved under NSF/ANSI Standard 60 (drinking water treatment chemicals). All ingredients in PAK® 27 have either “Generally Recognized as Safe” (GRAS) food additive status from the U.S. Food and Drug Administration (FDA) or exemptions from tolerances from the U.S. EPA. The active ingredient in PAK® 27 is sodium carbonate peroxyhydrate, which is an addition compound of sodium carbonate and hydrogen peroxide (H2O2).PAK® 27 is approved for use as an algaestat or algaecide for the selective control of blue-green algae in lakes, ponds, drinking water reservoirs, irrigation, drainage and conveyance ditches, canals, laterals, estuaries, bayous, lagoons, water gardens and water features, impounded water and waste water, and aquaculture.