Spa Essentials Chlorinating Concentrate is a spa and hot tub sanitizer. Customers prefer this product because it is a fast acting granular stabilized chlorinator that acts as a sanitizer and an oxidizer. This is a hard-working product that will kill and control bacteria - resulting in water that"s a pleasure to soak in. Spa Essentials brand chemicals are the easiest to use: reach and maintain beautiful spa water. 97% Sodium dichloro-s-triazinetrione.