CVBN, also known as "Gerbera Tabs" is essentially Chlorine. It sterilizes the stems and the bucket. Being a volatile gas, the Chlorine dissipates with time. A small amount may be absorbed into the plant, but in general this product is used for surface sterilization for plants with "dirty" stems. These are usually slightly fuzzy or hairy stems that allow bacteria to proliferate. Gerberas, Zinnias, Sunflowers for example. It also is said to neutralize Daffodil "slime."