# Water change temperature



## Jaseon (24 Feb 2021)

When you water change what do you shoot for with regards to getting the temps to match the tank. Do you look to get it exactly the same or dont mind being a few degrees out either way? Im guessing having your new water roughly there will dissipate in the tank with no noticeable change in temperature.


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## Sammy Islam (24 Feb 2021)

I usually add water that's 1°c cooler than what the tanks set at. Doesn't take long for it to heat back up to the desired temp.


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## Mr.Shenanagins (25 Feb 2021)

Within a few degrees is okay. I’ve matched my faucet to the tank with very small sharpie marks of where the hot and cold need to be. I change this when the weather changes because then the cold water comes out at tropical temps


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## Conort2 (25 Feb 2021)

I go a few degrees cooler as it normally kicks my Corydoras in to breeding mode.

Cheers


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## papa_c (25 Feb 2021)

Mr.Shenanagins said:


> with very small sharpie marks



Jeez that's brave ...... my Mrs would castrate me if I drew on the taps! 🤣


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## hypnogogia (25 Feb 2021)

I heat mine with a spare tank heater, so it is more or less the same as the tank water, as I mix rain water with cold tap water.


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## Jack B (25 Feb 2021)

You don't hear many (any?) bad stories so I assume it's not that big a deal. Erring on the side of cooler seems more common than hotter. Mimics the effect of rain after all.


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## Courtneybst (25 Feb 2021)

I normally go 1-2c cooler. On the rare occasion my tap plays ball I can get a steady temperature that matches the tank water. Otherwise, I've worked out the ratio of warm and cold water I need to add to reach the desired temperature.


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## ian_m (25 Feb 2021)

This is what I use. Makes plant fiddling, bit of cleaning, emptying water onto front lawn and refilling tank about an hour to do.
Water change heater project.

I and many other people have often run cold tap water straight into the tank, remembering to dose dechlorinator into tank first, yes tank temp can drop to 15'C but fish don't seem to mind.


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## Mr.Shenanagins (25 Feb 2021)

Jeez that's brave ...... my Mrs would castrate me if I drew on the taps! 🤣
Hence the “very small” lol


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## Jaseon (25 Feb 2021)

Jack B said:


> You don't hear many (any?) bad stories so I assume it's not that big a deal. Erring on the side of cooler seems more common than hotter. Mimics the effect of rain after all.


Im always reading about being careful of swings in temperature etc, but as you say it mimics rain. I would guess that water temperature in the wild isnt a constant either, but there's a fuss made of having a stable constant temperature. I dont know how many fish in the hobby could react to changes in temps...Discus maybe? i dont know.


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## dw1305 (25 Feb 2021)

Hi all,


Jaceree said:


> I would guess that water temperature in the wild isnt a constant either, but there's a fuss made of having a stable constant temperature.


We have a <"few threads about this">. My guess would be that fish that come from the Rio Xingu etc need a more stable temperature. 

cheers Darrel


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## Jaseon (25 Feb 2021)

ian_m said:


> This is what I use. Makes plant fiddling, bit of cleaning, emptying water onto front lawn and refilling tank about an hour to do.
> Water change heater project.
> 
> I and many other people have often run cold tap water straight into the tank, remembering to dose dechlorinator into tank first, yes tank temp can drop to 15'C but fish don't seem to mind.


Reading through the thread now. 

I read this guy on another forums who said sudden changes in temp can kill fish, and affect their immune systems. On the face of it i would agree if you were to lets say do a 50% and pour freezing cold water in. Even then where's the evidence for that, as it seems to be passed around the hobby as a statement of fact, and we go along with it. Im more inclined to say ok fair enough how do you know it affects fish immune systems?...how do you actually test for that?


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## Jaseon (25 Feb 2021)

dw1305 said:


> Hi all,
> 
> We have a <"few threads about this">. My guess would be that fish that come from the Rio Xingu etc need a more stable temperature.
> 
> cheers Darrel


Ill check it out.


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## mort (25 Feb 2021)

I just stick my finger in the new water as see if it's roughly the same, I don't mind a few degrees either way and nor it seems do the fish. 

I think this is only really a problem if you are doing massive water changes with a dramatic difference in water temperature.

It's also interesting with regards to lower temps to stimulate breeding behaviour, as there are a few breeders I've come across that had fish that actually responded better to a slight increase in water temperature, so not all fish are created equal.


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