The major difference between chloramine against chlorine is that chloramine is less volatile. It stays in the water longer and is less reactive with organic matter.

Chloramine is a chemical used to disinfect water. It is ammonia (NH3) bonded to chlorine. It resists breaking down and is used because of its stability in water. Many commercial chlorine removers can be used to remove the chlorine, but when used alone, ammonia is left over. 

Adding chlorine and chloramines to our drinking water is very important to keep people healthy. But the same chemicals which keep us safe can be very toxic to fish. Adding tap water with chlorine or chloramine to a tank can quickly kill off fish.
It can also kill off the nitrifying bacteria that keep your tank stable and healthy.

The simplest and most effective way to remove chlorine and chloramines from your water is using chemical dechlorinators. 
If your water is treated with chloramine. The dechlorinator reacts with the chlorine portion of the chloramine. The chlorine is eliminated, leaving the ammonia free in the water.

Ammonia is toxic to fish, even at low levels. So, if you use a simple dechlorinator that only contains sodium thiosulfate, you are solving one problem (chlorine) and creating a new problem (ammonia).  
 
 
Instructions:

• Add 2ml of aquarium water in to the test vial.
• Add 4 drops of the CHL reagent and swirl gently for 10 seconds.
• Allow to stand for 1 minute.
• Place the vial against the colour chart to obtain a reading.