People

• Pools with heavy usage will see a drop in alkalinity and require daily testing. People that use the pool secrete body oils that affect the water alkalinity. Human waste such as urine, saliva and perspiration can cause the alkalinity to drop in the pool water.
  
  

Tap Water

• Tap water in many regions has low alkalinity, which can lower the alkalinity in the pool. When you replenish the water in the pool with water from the tap that has a low alkalinity, the alkalinity in the pool will drop. Water should be checked after each filling if water in the region has a low level of alkalinity.
  
  

Debris and Rain

• Debris, dirt and leaves that blow into the water will lower the alkalinity if left in the pool. When debris floats around in the water or settles on the pool floor, it starts to degrade and affect the total alkalinity, pH and chlorine levels in the water. Areas where the rain is acidic will lower the pH, but can also lower the alkalinity. After a rainstorm, the water pH and alkalinity are checked and adjusted as needed.
  
  

Chemicals

• Chemicals added to the pool water will reduce the alkalinity in the pool water. Pools that have a high alkalinity need a treatment with either muriatic acid or sodium bisulfate, which also lowers the pH level in the water. Generally, adding 20 oz. of muriatic acid or 24 oz. of sodium bisulfate per every 10,000 gallons of water will lower the alkalinity.