Report Mps Allergy in Hot Tub Water Chemistry Posted February 22, 2015 It sounds like, and looks like a chemical reaction. Our source water is chlorine neutral, If we switch to liquid chlorine, (ie. bleach) could she have the same reaction to it? Her rash is only where the jets hit her back, legs and arms. I really doubt this is bacterial, between the ACE system and the weekly shocks, the FC level never drops below 2ppm at the least, if there is a high bather load that day, and that is quickly corrected with dichlor. How much and what kind of liquid chlorine should we use to take the place of the dichlor? She has a Dr. appt. in the morning so maybe he can tell us for sure if it is bacterial or chemical. Thanks for your help.