Proper water balance in any swimming pool or hydrotherapy pool can mean the difference between a safe, comfortable environment and exposure to deadly diseases. This is especially important in commercial environments, as the bather loads can reach into the hundreds a day, potentially exacerbating an already dangerous situation. Additionally, properly balanced water is clean, comfortable, and leads to happy swimmers. This post from Hayward gives some easy to follow guidelines for properly maintained water chemistry. This chart should be readily available to anyone charged with maintaning a clean, safe, commercial or residential swimming pool.
Here is an excerpt from the post: