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Common Name(s): Monochloramine
Molecular Formula: NH2Cl
Used For: Disinfectant in municipal water supplies
Caution: Don't inhale
Material Safety Data Sheet: Chloramine


Chloramine is increasingly being used to disinfect household water supplies, instead of using chlorine. It's advantages are that it is more stable, does not dissipate from the water before reaching the tap, significantly lower tendency to form chlorocarbons, does not produce a chloride odour and has an improved taste. Marine organisms are sensitive to chloramine, so it must be removed before use of tapwater.


Before use in any marine aquarium context, the chloramine should be removed from the water. In the case of chlorine, removal is as simple as leaving the water stand for a day with aeration, and the chlorine then simply dissipates into the atmosphere. Chloramine is much more stable than this, so requires chemical treatment to remove it.

If a tap water filtration device such as RO/DI or DI is being used, then the initial activated carbon stage will remove the chloramine from the water and it is not a concern. If for some reason tap water is being used directly (which is not a good idea in the first place), then there are some commercial dechlorinators available that will also remove / neutralise chloramine. However, take care, as some dechlorinators will only treat the presence of chlorine and not chloramine, so check the details on the bottle for the product.