What causes pebbles to fall off in pools?

Pebbles may fall off in pools due to a combination of water flow and erosion. Water currents can dislodge loose pebbles, especially if they are not firmly embedded in the pool’s surface. Additionally, sediment buildup and changes in water levels can contribute to the movement of pebbles. Over time, factors like temperature changes and chemical reactions in the water can also weaken the adhesion of pebbles, leading to their displacement.