Dry, stable, high available halogen sanitizing granular compositions with a rapid rate of dissolution comprising halogenated 1,3,5-triazine-2,4,6-triones and a dissolution accelerant that is an alkali metal salt of 1,3,5-triazine-2,4,6-trione are disclosed. The disclosed compositions may include inorganic and/or organic disintegration agents. Additionally, these compositions may contain other performance enhancing additives such as water clarifiers, algaestats/algaecides, surfactants, glidants, processing aids, and binders. These UV stable sanitizing compositions contain a high available halogen content, and are stable even when stored in high-humidity environments.