Did you know that the sun hastens the dissipation of chlorine, so the best time to add sanitiser is in the evening. If your sanitiser is added automatically (eg in a salt pool) while the pump is on, run it at night if you can, for best efficiency?
Having lots of swimmers at any given time will introduce more pollutants like body oils, perspiration, suntan lotion and so on, and you need to compensate by adding more chlorine. Encouraging pool users to shower first has merit, but welcome to the real world!
Heavy rain will usually make the water in your swimming pool lose its clarity (start to turn green, or lose its transparency).
