Pool Water Chemistry Cheat Sheet

Posted by John Keene

 Understanding pool water chemistry is an essential part of maintaining your swimming pool. You should be familiar with how different factors like chlorine, pH, total alkalinity, calcium hardness and cyanuric acid affect your water, pool structure and equipment.
Below is a table of recommended chemistry levels divided by pool type. Save or print this table and keep it with your water testing and pool supplies for an easy reference. Click the table for a saveable or printable view.

Free Chlorine (FC): Chlorine is a disinfectant that kills harmful bacteria and other organisms in your pool water. High levels can cause skin and eye irritation, and low levels harm sanitation.
pH: The pH in a pool measures the level at which your pool is acidic or alkaline. High levels will lead to cloudy water, scale deposits, filtration issues and reduced chlorine effectiveness. Low levels cause acidic water which can lead to eye irritation and corrosion.
Total Alkalinity (TA): The measure of your pool water’s ability to resist change in pH. High levels cause a stronger resistance to change and lower levels can cause rapid pH fluctuations.
Calcium Hardness (CH): Measures the amount of dissolved calcium in your pool water. High levels can cause cloudy water and scale deposits, while low levels can lead to corrosion.
Cyanuric Acid (CYA): Also known as stabilizer or conditioner. It forms a bond with free chlorine in pool water, protecting it from the sun’s ultraviolet rays that cause chlorine loss.