Consider the duration of the injury. There are two types of back pain: acute and chronic. Acute is a type of injury that is there for a few days and then goes away, best described as coming and going.. Symptoms are often reasonably intense and heal in around four to six weeks.
Pure water usually has a pH around 7. Lemon juice is acid: dissolved baking soda is alkaline. (Properly speaking, dry materials don't have a pH.) Balance chemicals help you to avoid damage to your pool, either in the form of corrosion or scale deposits. Actually, it's a bit more specific than that: balance chemicals allow you avoid problems that result from having too much or too little limestone in the water (calcium carbonate).
The need for on-going use of pool chemicals also can cause corrosion of metal around pools, in the mechanical room where off-gassing of chlorine and Muriatic Acid can cause damage to all metals. Salts, chlorines and other chemicals will corrode metal, even stainless steel, that is not protected.