Biospot Effervescent Chlorine Tablets are recommended around the world as the safer, more effective, economic and convenient disinfectant. Biospot Effervescent Chlorine Tablets are based on a dry chlorine donor, Sodium Dichloroisocyanurate (NaDCC) which is blended with effervescent components before being compressed into tablet form. The result is a fast-dissolving, highly convenient, safer and more accurate alternative to liquid bleach.