Many other conditions sometimes cause weakness (see Table: Some Causes and Features of Muscle Weakness). For example, electrolyte abnormalities (such as a low level of magnesium or calcium) can cause weakness that sometimes comes and goes, as well as muscle cramping and twitches.
For swimming pool chlorination, see Swimming pool sanitation. Water chlorination is the process of adding chlorine (Cl. 2) or hypochlorite to water. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, typhoid etc.
Chlorine is the chemical most often used to keep swimming pools and Jacuzzis free of bacteria that can be hazardous to humans. Chlorine kills bacteria though a fairly simple chemical reaction. The chlorine solution you pour into the water breaks down into many different chemicals, including hypochlorous acid (HOCl) and hypochlorite ion (OCl-).