It is a fact that rain will decrease your Total Alkalinity level in the pool over time, requiring a pool owner to raise the alkalinity. … Heavy rains will dilute your pool alkalinity level, causing it to fall by 5-10 ppm a day. Low Alkalinity and low pH levels in pools can create a corrosive water environment.

Does rain cause high alkalinity pool?

Rain almost immediately causes the pH (Potential Hydrogen) in the pool water to rise while also reducing the TA (Total Alkalinity) slightly via dilution. Higher pH will cause more of the chlorine in a pool to become inactive or “fall asleep” reducing it’s effectiveness.

What causes pool alkalinity to drop?

There is a perfectly natural reason for this: evaporation and agitation of your water leads to a drop in the total alkalinity. … and high heat levels will increase the water evaporation and degassing phenomena. For all these reasons, the total alkalinity in your swimming pool will fall continually during the season.