An alternative to chlorine that pool owners use to kill bacteria, living organisms, ammonia, and any other contaminates (such as dirt, debris, or algae spores) that are in pool water. Bromine does come in granular form, but by far, the most common form of bromine is the tablet. The main reason that bromine is not chosen as often as chlorine in pools is that it is fairly expensive. Bromine's niche is with spas (hot tubs), as it is more stable than chlorine in the hotter water temperatures that are associated with spa use.