Essential to prevent the water in the small intex pool with a diameter of 2.44 from getting cloudy, along with algaecide liquid. It smells like chlorine, but not unpleasantly, dissolves very slowly. According to the dosage and some comments I read, I broke the large tablet into 4 pieces and added one. However, be careful to use a plastic dispenser because it will discolor the pool if it touches directly.