Matching Water Temperature

[blfoster]

When I do my weekly water change, I try to get the water I add as close to the temperature of my tank as possible by mixing the right amount of hot and cold water. I'm wondering how close it really needs to be. I've calculated that when I do a 20% water change, I would need to be off by 5 degrees to cause a change of 1 degree in the tank temperature, so it doesn't seem like it needs to be that close. I always get the water I add wthin 1 degree, but that takes time.

 

[Miss Wiggle]

When I do my weekly water change, I try to get the water I add as close to the temperature of my tank as possible by mixing the right amount of hot and cold water. I'm wondering how close it really needs to be. I've calculated that when I do a 20% water change, I would need to be off by 5 degrees to cause a change of 1 degree in the tank temperature, so it doesn't seem like it needs to be that close. I always get the water I add wthin 1 degree, but that takes time.

unless your fish are especially sensitive to temp changes don't worry about it. The vast majority of fish can handle a fluctuation of a couple of degrees, it's no worse than them heating a bit in summer then cooling down at night.

 

[andywg]

I change 40% on my big tank with water straight from the cold tap, and there are no heaters in the actual tank, still never see the temp dip by more than about 2 or three degrees.

You can be out by 18 degrees on a 24 degree tank and still only have it drop by 2.4 degrees in the coldest part of winter with 20% changes.

You will find that almost all people with larger tanks will water change straight from the cold water tap, uinless doing very large changes.

 

[SamUK]

When I do my weekly water change, I try to get the water I add as close to the temperature of my tank as possible by mixing the right amount of hot and cold water. I'm wondering how close it really needs to be. I've calculated that when I do a 20% water change, I would need to be off by 5 degrees to cause a change of 1 degree in the tank temperature, so it doesn't seem like it needs to be that close. I always get the water I add wthin 1 degree, but that takes time.

i did the same till i read what andy said a few months back.


now i jus fill from the cold tap.


i jus run the hose slowly. fish seem to like it too cos they play in the bubbles from the hose.

 

[Tolak]

20% with cold tap water works fine, as long as you fill it a little slower. Water changes with colder water is a method used to induce spawning in many fish. Spawning fish are happy fish.

 

[blfoster]

Great, thanks everyone.

 

[Tokis-Phoenix]

I try to make sure the water temp of new water is as close to the existing water in the tank- temp fluctuations can be bad for fish particually small bodied ones who are more sensitive to these things.
In the past i once did a water change with cold water and one of the guppys who swam into the flow of cold water later came out with a bout of septicemia that day. Ever since then i have adjusted the temp carefully (by testing the temp with my hand) and never had any issues since.

Even if some people do cold water changes, it cannot be benneficial for all species/types of fish; i know that cories can often spawn after a cold water change, but this is only because in their natural habitat they spawn after the rains flood the rivers and lakes after the long dry season- cories are programed to spawn when faced with dramatic change in water quality or temp changes (reflecting the wet seasons changes and flooding). Sometimes transporting cories for long periods of time and then putting them in a tank is enough to make them spawn, but this obviously isn't great thing for them.
I guess doing a cold water change in a tropical tank would be like being chucked into a cold bath i.e. it wouldn't kill you but it sure would be unpleasant and could make you a cold.

 

[SamUK]

do you think the same applies if its run in slowly tho?


i mean i kno its not ideal but it takes about an hour to refill my big tank (dont use the hose on the smaller tanks) and the temp drops a couple of degrees but surely over an hour they shouldnt notice too much.


id never fill buckets with coldwater and jus chuck them in cos that would be like jumping in a cold pond but i didnt think it was as bad as the temp takes a while to drop?

 

[Tokis-Phoenix]

do you think the same applies if its run in slowly tho?


i mean i kno its not ideal but it takes about an hour to refill my big tank (dont use the hose on the smaller tanks) and the temp drops a couple of degrees but surely over an hour they shouldnt notice too much.


id never fill buckets with coldwater and jus chuck them in cos that would be like jumping in a cold pond but i didnt think it was as bad as the temp takes a while to drop?

Pouring the water i slowly gradually will help a lot, but even if you add a bit of warm water to the new water you put in the tank i am sure it will make the water change a lot more pleasant for your fish - how do you fill your tanks up or go about water changes?

 

[Tolak]

I think a little bit of common sense needs to be used here as well. If you keep your tanks at 80F, & do a 50% w.c. with water that is 50F with a hose wide open on a 20 gallon, you will fill that tank in around 5 minutes. You just dropped the temperature to 65F, bad news.

Do a 20% w.c. on a 100 gallon with those same water temps, letting it run in slowly over an hour, it would be a 6F change, not counting the heater helping to heat the tank, ending up with a few degrees difference over an hour. This won't bother all but the most sensitive fish. I've done it with larger angels, it's a spawning method.

If you are doing a smaller change, and have the time, slow down the flow & use cold. A larger, faster change, match the temp & open it up. I do 50% to 80% in most cases, with a hose cranking it in, I match the temperature.

 

[SamUK]

Pouring the water i slowly gradually will help a lot, but even if you add a bit of warm water to the new water you put in the tank i am sure it will make the water change a lot more pleasant for your fish - how do you fill your tanks up or go about water changes?

i thought about adding hot water but surely unless i added it slowly like the hose going in with the cold then id cause the temp to rise which is jus as bad. i spose you could jus add a lil bit every few mins but again i dont kno if that would cause more temp fluctuations than if you jus left it to drop slowly.

personally i use the hose through my bedroom window on my big tanks (180G and 80G) but on my smaller tanks i still use a bucket and get the temp roughly the same (with my finger).


i guess it wouldnt make any difference if i did jus use the hose because im still replacing the same amount of water (in ratio) so the temp drop should be the same........ i think.


dnt like doing it tho still so i stick to the bucket on them.

 

[Ginge]

And i have heard stuff in hot water tanks cant be good for the fish anyway.

 

[Tokis-Phoenix]

Pouring the water i slowly gradually will help a lot, but even if you add a bit of warm water to the new water you put in the tank i am sure it will make the water change a lot more pleasant for your fish - how do you fill your tanks up or go about water changes?

i thought about adding hot water but surely unless i added it slowly like the hose going in with the cold then id cause the temp to rise which is jus as bad. i spose you could jus add a lil bit every few mins but again i dont kno if that would cause more temp fluctuations than if you jus left it to drop slowly.

personally i use the hose through my bedroom window on my big tanks (180G and 80G) but on my smaller tanks i still use a bucket and get the temp roughly the same (with my finger).


i guess it wouldnt make any difference if i did jus use the hose because im still replacing the same amount of water (in ratio) so the temp drop should be the same........ i think.


dnt like doing it tho still so i stick to the bucket on them.

Ah, when i do water changes i take the water out via buckets and fill the tank up via buckets- that way i can mix the warm water and cold water creating the right temp in the bucket before adding it to the tank.
If you have a shower you may be able to attach a hose to it, so you can adjust the temp of the water coming out of the shower into the tank .

 

[Fwapp]

I too try and match temps a close a possible, but am intrigued by people saying that they feed water in direct from the cold tap. When you feed the water in do you add the dechlorinator at the same time? or before/afterwards? Also do you dose for the tank volume or the volume you have replaced?

Please do give a response, as I can feel a reduction in bucket-hefting coming on!

 

[SamUK]

Ah, when i do water changes i take the water out via buckets and fill the tank up via buckets- that way i can mix the warm water and cold water creating the right temp in the bucket before adding it to the tank.
If you have a shower you may be able to attach a hose to it, so you can adjust the temp of the water coming out of the shower into the tank .

yea i used to do that but it took far too many buckets.

my bedrooms downstairs and the showers up so i use the kitchen tap but thats pretty rubbish. were getting a new sink tho soon i think so i mite see about a python then cos i do agree it is better to get the temp right.

the hot tap pressure isnt much more than a trickle downstairs tho so im not sure ill be able to do it even then (and its another reason why buckets was so painful).

oh and i jus siphon out the window too.

jus stick the hose over my filter output to get it goin and sit back for 10 minutes.