Conditioning tap water (removing chlorine)

Fish close view

Running tap water

Conditioning tap water is essential in aquariophilia. Fortunately, it’s extremely simple!

In order for tap water to be consumed by humans, it is freed of bacteria and various pathogens through the use of chlorine. Chlorine is well identified by the smell of the water and its characteristic taste.

Unfortunately, chlorine is toxic to our fish (burns gills, among other things) and also destroys the beneficial bacteria in the filter. It is therefore necessary to get rid of it before any water change.

How to remove chlorine from tap water?

Seachem Prime Water Conditioner

There are 2 methods: one method can simply be to let the water rest in a bucket for 24 to 48 hours before adding it to the aquarium (make sure that the replacement water is at about the same temperature before pouring it into the tank). It is recommended to stir it on the surface with an air pump to ensure that the chlorine is properly discharged; you can also filter it with activated carbon (which removes chlorine and heavy metals).

However, many water companies now use chloramines to prolong the effect of chlorine: chloramines cannot be neutralized by the first method. If your water contains chloramines (contact your local water authority or ask your nearest pet store), a water conditioner should be used to break down chloramines and eliminate chlorine (most aquarium water conditioners can do this – read the label on the bottle carefully). If you do not know if your water contains chloramines, to stay on the safe side, get a good quality water conditioner from your pet store.

Good water conditioners can also help to neutralize heavy metals that may be found in tap water (metals can have a long-term negative effect on fish).

Among the best brands of water conditioners, we can mention: Seachem, AquaCare, JBL, API, Tetra, Aquarian, Sera, Fluval, Interpet, Easy-Life, NT Labs and Waterlife.


Warning:Exclamation mark
The approximate temperature of the water used when changing water should be as close as possible to the temperature of your tank. Indeed, water changes with water that is too cold can lead to white spot disease, for example.