These Environmental Protection Agency (EPA)-registered sodium carbonate peroxyhydrate products are fast acting algaecides (algae killer) or algaestats. Algaestats do not kill algae outright but instead inhibit their growth, preventing bloom formation. Lake managers apply these products to the water to prevent algal blooms or to treat existing algae. Lake managers use these products as an alternative to copper-based algaecides not allowed in most Washington water bodies. In some parts of the world, there are copper-resistant algae strains and these products provide an alternative to treat copper-resistant algae.
The EPA registered sodium carbonate peroxyhydrate products for use in ponds, lakes, reservoirs, and drinking water sources. Sodium carbonate peroxyhydrate acts as an oxidizing agent to kill algae. When applied to water, these granular products break down into sodium carbonate and hydrogen peroxide. Some anecdotal evidence suggests that sodium carbonate products are more effective when used to prevent the occurrence of algae blooms. Waiting until the water turns green may not be the best time to treat. Some people claim that these products successfully spot-treat filamentous algae. Several brands of sodium carbonate peroxyhydrate products are on the market including GreenClean™ and Pak 27™. Some brands are advertised as being selective to blue-green algae.