Author: Dr. L.E. Freese
What is chloramine?
How do I know if there is chloramine in my tapwater?
Is chloramine dangerous to my fish?
How can I remove the chloramine in tapwater?
Chloramine
What is chloramine?
Chloramine (NH2Cl) is a compound that is formed when
chlorine and ammonia combine in water. The ratio normally is 1 part
ammonia to 5 parts chlorine.
Chloramine is also formed if the water supply is treated with sodium
hypochlorite powder instead of chlorine gas.
It is used in certain areas to kill bacteria in tap water instead of
chlorine. This is due to certain factors:
- Chlorine forms trihalomethanes (THM)
- Chloramine stays in the water for much longer than chlorine
- No unpleasant odour or taste
The problem with this is:
- Need higher levels of chloramine than chlorine
- Chloramine is stable and very difficult to get rid of
How do I know if there is chloramine in my tapwater?
The best way to find out is to phone your water supplier and ask them
what is used to treat your water and if chloramines are present.
Is chloramine dangerous to my fish?
Yes, Chloramine is very toxic for fish and other aquatic life forms.
Chloramine acts differently to chlorine in that it causes little damage
to the gills but passes through the membrane and into the bloodstream.
Here it binds to the iron in the haemoglobin in the red blood cells. This
prevents the blood from carrying oxygen and this leads to a disease known
as methemoglobinemia, similar to nitrite toxicity. This causes the fish to
become very lethargic and eventually they die.
How can I remove the chloramine in tapwater?
As chloramine is very stable and does not dissipate easily from the
water, even with heavy aeration. If this is the method that you want to
use, then the water must be exposed to sunlight and aerated for at least a
week.
The chloramine compound can be broken by having very low flow rates
(5-10 min contact time) through activated carbon followed by mineral
zeolite media to remove the ammonia. This poses the problem of who has a
mechanism where the contact time is this long and before the water reaches
the aquarium? When using this method, one must ensure that the activated
carbon and the zeolite are new enough for the chemical reactions to be
able to take place.
RO (Reverse osmosis) does not remove chloramine, as the chloramine is
able to pass through the permeable membranes just s it can pass through
the membranes of the fish’s gills.
Anti-Chlorine destroys the chlorine and ammonia bond and removes the
chlorine. The nitrifying bacteria in the established biofilter will remove
the resultant ammonia. Therefore it is not advisable to clean the filter
and do a water change of greater than 10% at the same time.
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