A dispenser for dispensing solid or liquid water-conditioning/treating agents into a body of water (such as a pool, hot tub, or the like) comprises a hollow body adapted to receive water treating agent which can be solid (tablet form), granular, powder or liquid. The dispenser has an overall specific gravity such that, when the dispenser is substantially empty of water-conditioning/treating agent(s), the dispenser will float, but when the dispenser contains water-conditioning/treating agents, the dispenser will sink.