SpaSILVER - Concentrated Colloidal Silver - 500 mL bottle An all natural, odor free, safe and effective way to keep hot tub/spa water clean Use by itself or concurrently with a UV system or a reduced traditional water treatment program Keeps water fresh longer Contains .9999+ pure Silver as bioavailable nanoparticles colloidally suspended in pure water Long lasting, does not evaporate as do chlorine or bromine treatment programs