How to Tell If a Swimming Pool Has Too Much Chlorine. Keeping the proper chlorine level in your pool is very important for two reasons. First, chlorine keeps the levels of bacteria that could cause cloudy water and algae growth down. Second, you need to make sure that there isn't too much chlorine in the water, because this could cause eye and skin irritation.
Purchase a good-quality test kit that can test the levels of chlorine. You might want to think about spending more money for a DPD chlorine kit. This kit will measure free, combined and total chlorine levels. If you use an OTO kit, you will only be able to measure free chlorine levels.
Read all instructions on the test kit that you purchased. There are many different kits out there, and the directions will differ. The recommended swimming pool chemical standards set forth by the National Spa and Pool Institute are between 2.0 and 4.0 ppm for free chlorine and none for combined chlorine.
Know that if you can smell the chlorine in the water but your test shows that there isn't any chlorine, then the level of chlorine is probably excessively high. In this case, the chlorine probably bleached out the reagent used in testing. You need to either dilute your sample of pool water with an equal amount of chlorine-free water or double the number of DPD drops used in the test. You would then either divide or multiply depending on which method you chose.
Public pools should undergo chemical testing every hour, while household pools should undergo testing a few times per week.