does anyone know whether products like "SuperNatural ExcelloFizz" are worth a shit?

here is what it claims..

Benefits: Excellofizz as a CO2 producer: Excellofizz is safe to use around people and pets and will not raise the CO2 to dangerous levels. Excellofizz is economical for small to medium size greenhouses. Requires no expensive dispensing or monitoring equipment. Excellofizz will not add heat or moisture to your greenhouse. In fact it will remove some heat and moisture. Excellofizz contains pure natural environmentally friendly ingredients that can be safely disposed of. Excellofizz is simple to use, just add water to activate. Excellofizz releases a refreshing fragrance of eucalyptus which absorbs odors and may deter insects. Excellofizz is available as a single puck, 10 puck, or in a 50 puck container.