What is the cause of plaster popping off in multiple locations on a 7-year-old pool?

Several factors can contribute to plaster popping off in multiple locations on a 7-year-old pool. Here are some common causes:

1. Improper Installation: If the plaster was not installed correctly during construction, it may have insufficient bonding strength with the underlying concrete substrate, leading to popping and delamination over time.

2. Water Chemistry Imbalances: Incorrect water chemistry, such as high levels of calcium hardness, pH imbalances, or excessive alkalinity, can weaken the bond between the plaster and the concrete, causing the plaster to pop off.

3. Structural Issues: Movement or settling of the pool structure, such as shifting or sinking due to improper compaction or weak soil conditions, can cause stress and cracking, resulting in plaster popping off.

4. Freeze-Thaw Cycles: In areas with fluctuating temperatures, repeated freezing and thawing can deteriorate the plaster and cause it to chip or pop.

5. Hydrostatic Pressure: High water pressure behind the plaster, often due to improper drainage or blocked weep holes, can exert force and lead to plaster popping off.

6. Poor Water Circulation: Insufficient water circulation in the pool, especially in areas with high temperatures, can lead to localized heating of the plaster and its subsequent popping.

7. Chemical Treatments: Overuse or incorrect application of harsh pool chemicals, such as concentrated chlorine solutions or acidic cleaning agents, can weaken the plaster and lead to popping.

8. Age and Wear: Over time, even with proper maintenance, the plaster can deteriorate due to continuous exposure to chemicals, water pressure, and general aging, resulting in popping.

To determine the exact cause, it is recommended to consult with a qualified pool professional who can inspect the pool, evaluate the plaster condition, and recommend appropriate solutions to address the issue.