Some interesting text in a newsletter from the Pool Guy who installed our pool.
Until I read this, I didn't know acid rain was affecting my water balance so much! (sarcasm)
"RE-BALANCING YOUR POOL WATER BEFORE CLOSING!!!
The last thing most people want to do in the fall is spend more money on their pool- especially when closing it. However, the damage that can be done to your pool if water balance is ignored can be devastating! Low pH turns your pool into an acid bath during the winter which causes damage to your pool surface, paint, and liner. Many customers believe that once they balance their pool water in the spring, it is good for the season. Nothing could be further from the truth. Youíve heard of acid rain, right? Well, itís not a myth. When it rains, the rain water which falls into your pool is very acidic. This causes your alkalinity and pH levels to fall, which in turn causes the calcium hardness level to fall because the pool water requires more calcium at lower pH levels. The result is a negative saturation index, a term used to describe the balance of your water in regards to alkalinity, pH, and calcium hardness. Most people donít see these changes in their pool water, except that it looks cleaner and clearer than usual. Proper water balance is essential to keeping your pool ready for the winter. So bring in another water sample and have us analyze it for FREE and keep your pool clear and balanced for the winter!"