Pools that are unattended, without chemicals, circulation and cleaning, don't last long. Within weeks, they become green, and within months, they become home to frogs and mosquitoes.

There are situations where it is necessary to change the water immediately, no matter the other factors. Foul odors, green water, slimy walls, excessive debris, and cloudy water are all signs that the water is unsafe and should be changed.

The use of chlorine Chlorine is the most popular treatment for keeping swimming pool water chemistry balanced because it's highly effective and relatively low cost. Other disinfectants include bromine, ozone, and ultraviolet (UV) radiation.