Jelly Bean Tetra - Ladigesia roloffi - Federation of British Aquatic ...

Q: When doing a partial water change on tropical tank, how do I get the
replacement water to correct temperature before adding to the established
water already in the aquarium?
A: Whilst most people try to add replacement water at the same temperature
of the existing aquarium water, it is not absolutely necessary to do so and
many aquarists simply use water straight from the tap- often through a
hosepipe.
To digress a little, some tropical fish, Corydoras catfish for instance, can be
triggered into spawning by adding far cooler water to their tank.
This imitates Nature where melting mountain snow runs down to fill the rivers;
where this causes the rivers to overflow, the knock-on effect drowns millions
of insects on which any baby fish can then feed. Hence adult fish, upon
sensing a cooling down of water temperature, quickly get into breeding
mode!
But back to your question. If you only take out a reasonable amount of
water from the tank - let's say a large bucketful/ a couple of gallons –
just standing the bucket in the same room for an hour or two will warm it up a
bit, even more so if you have a space-heated fish room.
Alternatively, you could warm the water up in the bucket by adding a kettle of
boiling water or even use a spare aquarium heater to heat up the water to the
required temperature.
When using water from the tap, it is advisable to use water-conditioning
agents to neutralise heavy metals and/or chloramines present in the water.
Notice that the word ‘dechlorinator’ has passed out of use as old-fashioned
chlorine is now no longer in regular use by the water authorities.
In some areas, rain water from the butt may be acidic due to atmospheric
pollution or otherwise contaminated from dirty roofs and metallic
guttering.
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