More specifically, it lowers the pH and TA and increases chloride (salt). Generally speaking, the amount of salt buildup from Muriatic Acid is far smaller than than from chlorine, but even that is a rather slow buildup since salt is rather innocuous except at much higher levels. With bleach or chlorinating liquid, at 2 ppm FC per day chlorine usage the salt increases by around 100 ppm per month if there is no water dilution.