Standard activated carbon (coconut shell or coal based) does a very good job offiltering free chlorine but is minimally effective at removing chloramines (sometimes called "combined chlorine").
When chlorine comes into contact with activated carbon, it reacts chemically andproduces chloride, a harmless compound. Activated carbon filters are great forremoving standard chlorine from the water because they have a large surface areaand exchange sites. But chloramines as a substance are unique in their stability.They are not catalysed with the same efficiency and speed when in contact withactivated charcoal.
Activated carbon has very long contact times to effectively remove chloramines byseparating chlorine from ammonia. That makes activated carbon a poor choice forchloramine reduction as you cannot shower or run a full water bath at such a lowflow rate. Skin sensitivity is one of the primary reasons people want to get rid ofchloramines, so a filtration system that is able to maintain at least a moderate flowrate is key to success.
