Chlorine V. Chloramine
There are many similarities between chlorine and chloramine. Both provide effective residual disinfection with minimal risk to public health. Both are toxic to fish and amphibians. Both chlorine and chloramine react with other compounds in the water to form what are called "disinfection byproducts".
The difference is that chlorine forms many byproducts, including trihalomethanes (THM) and haloacetic acids (HAA), whereas chloramine forms a significantly lower amount of THMs and HAAs but also forms N-nitrosodimethylamine (NDMA). One of the principal benefits of chloramine is that its use reduces the overall levels of these regulated contaminants compared to chlorine.
Read more about this topic: Chloramination