Water temperature during water change

  • #1
reading this now to myself it sounds a bit strange but lets see  :-* I have a 1,000 litre tank and if I was to change 50% of the water (500 lts) with fresh chlorinated water,  obviously with the amount of water change the temperature would drop considerably. so my question is - would I be able to fill one bucket with cold water, the 2nd with hot water  straight  from tap and vice versa until the tank is full again? PS my aI'm is to keep the water at the same temperature  so I don't stress the fish out during the BIG water change. thanks for reading  ;D o

  • #2
HI there
just wanted to let you know how I do my water changes to match the same temperature as the tank water. I take the thermometer out of the tank, and check the reading. Then at the tap I just get the water to the same temperature by checking it with the thermometer. Then I know the water I am putting back into the tank is exactly the same temp as what is in the tank. I use a five gal bucket for emptying the tank water, and another for putting new water back in. The tap water is treated with Prime before going into the tank. That's all there is to it for me. I have a well, so no worry about chlorinated water, but I believe that Prime takes care of that problem for you if you use it.
hope that helps to answer your question. ~ kate

  • Thread Starter
  • #3
thanks Kate. so after you've filled the bucket with cold water from the tap, you then add hot water from the tap to adjust the temp in the bucket to the same temp in tank? thanks. PS . just wanted to clarify that its safe to add hot water straight from tap ( with few drops of API stress coat conditioner)
  • #4
thanks Kate. so after you've filled the bucket with cold water from the tap, you then  add hot water from the tap to adjust the temp in the bucket to the same temp in tank? thanks. PS . just wanted to clarify that its safe to add hot water straight from tap ( with few drops of API stress coat conditioner)
I adjust the water coming from the tap to the temperature I want it to be. This is the water that I put in the bucket. I don't use cold... then hot... then cold.. then hot to get to the right temperature, that would take forever trying to get the right temperature. Its a lot easier to just turn on the water from the faucet to warm, check the temperature coming out of the tap by using the thermometer that I hold under that faucet, once I get to the right temperature I want, I start filling the bucket. I add my water conditioner also at the same time.
~ kate
  • #5
Just let your tap water run with both hot and cold on so you get a mix that is close to your tanks temperature. Also depending on how often you do these water changes, you are better off doing less water more frequently then large water changes once and a while. If you are doing these 50% water changes every week then no problem, but if you are only doing them every 2 or more weeks then you might be causing more stress then is needed on your fish. You would be better off doing 20%-25% water changes weekly then 50% ones every 2+ weeks. Even if the water conditions are bad, the fish will get used to it to some degree, and then if you go and add a lot of new water, the conditions will suddenly change from bad to good in the tank. The problem is the word "suddenly" as any quick change (even if it's from bad to good water) stresses the fish. It's much better to keep things stable in the tank and slowly make changes to water quality. If you are doing the 50% every week then it should be ok, but you might be stressing yourself out unnecessarily . If your nitrates are around 10ppm after the change and only rise say to around 20ppm after a week, just change enough water to get it back down to around 10ppm. It could be less then 50%, but might take a bit of experimentation. Just throwing that out there.
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  • #6
for the last 10 days or so Ive been doing 20% daily water changes to try to bring my nitrate levels down from 40ppm . todays reading shows the levels have dropped to 10ppm which I'm happy with. Doing just 20% water changes and adding just 'cold' conditioned water hasn't done much to drop the temperature in the tank due to the volume of water it holds. I also read that 50% water change now and again is more likely to stress fish than a 25% water change more often. thanks for all your input regarding this,

  • #7
You have a 1000l tank! My god that must take days to maintain. P.S. am also very jealous
  • Thread Starter
  • #8
armadillo . the larger the tank the easier the maintenance so I'm told ! Ive had the tank around 2 years now and all is good. usually consists of weekly water change (20%) unless nitrates are high. clean the glass and gravel and every 2 months clean the powerful eternal filter which keeps the water crystal clear. this little bit of maintenance is nothing compared to the pleasure I get from it. now added lots of plants and looks pretty good now. must get pics as soon as I get my hands on a digI camera.
  • #9
What about the gravel vaccuuming. Does that take a lot longer? And the water changes, do you carry hundreds of buckets around or do you have a fancy system? I'd love to save up and get a bigger tank, but I want to know what am setting myself up for.
  • Thread Starter
  • #10
the only hassle I suppose during maintenance is the water changing which requires filling the bucket up with water x4 then transferring it to the tank ( so not much work involved ;D ) the external filter has a valve which I attach a pipe to and then able to drain the water straight out into the drain so no heavy lifting. I have a lot of snails in my tank which come to life during the night when lights are off and these really help with cleaning of gravel. PS if I'm honest I don't clean gravel that much myself and 90% of the time all my API test reading are good. ( also my clown loaches help to keep the snail population down a little) Ive some plants in tank like Java moss which snails seem to leave alone. so genearally not a lot of work involved at all and fish seem happy so must be doing something right ;D if I was to sell the tank I would definitely have to get a decent size one again. lucky I have patio doors leading to living room or the tank would not fit into the house through normal sized doors :-[

  • #11
OK, 4x is fair enough I suppose. It's 2x 2 for me (only have 50L, but filling and emptying require a trip with bucket), so that's not that much of a change. How come, if your tank is 20x the size of mine? Am not that practically minded, sorry. Probably a stupid question.

So the valve empties it, but you have to carry the water to fill it again, is that it?

Was a bit worried about getting snails for some reason. I think I read of outbreaks at times, and how a lot of diseases treatments for fish would kill the snails off. But that was from the corner of my eyes. Good to hear good feedback about them.

Thanks for your enlightening responses. Am more and more thinking of going big... My next step is 150L, and we'll see if I can handle that. That's already 3x the size, so it's a decent step up.
  • Thread Starter
  • #12
basically that's all there is to it. check out 'fluval fx5 external filter' on google. pretty expensive but well worth it in my opinion. I had a 150l tank and I was always changing the water because it soon got cloudy. maybe someone else out there can answer the question why a larger tank needs less maintenance than a smaller one. I know that when we had a power cut ( 12 hrs) and the temperature dropped considerably all the fish survived because the more water in the tank the longer it will stay warm if the heater was to pack in.

I think snails add to the natural look but I do agree with you that some may carry diseases and they can breed like mad ;D if I really wanted to get rid of a few id leave some lettuce or cucumber in a jar and within 2 hours or so the jar would be full of them then id get rid of them. but at the moment they are manageable lol

There is one downside after all ;D at night when the tank is lit up I tend to watch the fish rather than the repeats on tv ;D the tank lights up the living room and is very relaxing to watch
  • #13
Oh, so it was true about the snails not always being welcome? Really wasn't sure. I think I'll steer clear of them. Don't want the moral dilemma of having to dispose of the excess population! Meet the chairwoman for the defense of invertebrates!
  • #14
maybe someone else out there can answer the question why a larger tank needs less maintenance than a smaller one.
Think of it like this, take a small cup of water and drop 1 drop of food coloring into the cup. Chances are that the water just turned a new color. Now take that same single drop of food coloring and drop it into a 5 Gal (19 L) bucket of water. Chances are you didn't see anything happen other then the drop just completely dissolve into the water and disappear. The same holds true for adding ammonia (though fish waste and food) or whatever chemical you are adding to the tank though whatever means. In a small tank you are going to see the concentrations of that chemical rise at a much faster rate because there just isn't as much water in the tank to dilute it to non-existence like the drop of food coloring in the large bucket. So maintenance is required much more frequently in the small tank compared to the large one simply because of it's large volume. There is more too it then that (i.e. if you have an overstocked large tank you will have just as much problems as a small tank, etc.) but you get the idea.


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  • #15
very well explained Luniyn, make sense now. so bigger is better ;D
  • #16
very well explained Luniyn, make sense now. so bigger is better ;D
No matter what she tells you... oh sorry... wrong discussion . But yeah that's why it is always highly recommended to get the largest tank you can afford as your first tank and not these little 5 or 10 Gal "Starter" tanks the pet stores try to sell you. The have their place, but a newbie will have a much easier time with a larger tank because it leaves more room for error.
  • #17
I read here that once I add fish to my tank and do water changes I need to make sure the temp of the water I add is as close to the one in the tank...how do I do that? thanks
  • #18
I purchased a cheap digital kichen thermometer that I use to find the temp as I turn the knob on the bathtub, then I fill the bucket and double check the temp once it is full.


  • #19
I use my finger.
  • #20
I use my finger also I put my finger in the tank water to feel the temp and then do the same when adjusting faucet.
  • #21
Good morning,

I have moved your thread to the Aquarium Water/Temperature section of the forum.

You can use an aquarium thermometer to make sure the new water added is the same, or close to within 1 or 2 degrees, as the water in the aquarium. Sudden changes in water temperature can be fatal to your fish.


  • #22
We go by touch when first setting the faucet for the python and then, as Ken suggested, we watch the thermometer during the fill. If it varies by more than 1 or 2 degrees, we adjust the faucet water accordingly.


  • #23
thanks to all I think I'll buy another thermometer..cant trust my fingers I'm always cold!
  • #24
I highly recommend the digital thermometers rather than those tube ones. They're easy to read and pretty accurate. Some models also allow for an alarm hookup, so that if the temperature goes outside of boundaries you set, the alarm goes off.
  • #25
  • #26
when getting tap water any point using Hot to reduce clorine?

if you are patient, and going to add water later in the day does it help to use Hot Water,
let it sit for 1/2 day in bucket to come to room tempature, to speed up release of Clorine, and add the Stress coat or AquaPlus at end of day

is it better to add Stress coat or AquaPlus in the hot water or let the Stress coat or AquaPlus sit for a few hours before adding to tank?


  • #27
  • #28
Aloha again. You might remember me from such threads as "Aloha, new member here".

I have a question about water temperature. I also have a sub-question about chloramine.

First - I've been using spring water for water changes. When I had two goldfish in an unheated aquarium it was no problem but now I've got fancy guppies at 78 degrees and it's a bit of a logistical problem to get gallon jugs of water heated up to the proper temperature and keep them there while I do the water change.

So my idea - if I gradually lower the water temperature in the tank then I can avoid shocking the fish when I add room temperature water. This brings up my first question;
Are the guppies going to be okay at 68 (or so) degrees for a little while? I've lowered it from about 78 down to about 73 already and everything is muy bueno so far. (No ka oi if you're kama'aina like me. You can ignore that if you think I've had too much caffeine. )

My second question regards chloramine. I've read some articles that say that chloramine is difficult to remove from tap water. My local utility just switched over to chloramine in spite of a huge stink in the paper. A few people claimed that now they can't use tap water for their fish tanks. So is it? I can keep getting spring water for free (I've got hook-ups) but the temperature problem is making me think about how tempting it would be to be able to adjust the temperature coming out of the tap.
  • #29
Solution #1 for the bottles of spring water. Run some hot water in the tub and place your jugs in it to warm up. 1 gallon jugs won't take long to warm to 78 degrees. Shake the jug occasionally, and test the temp before using it. It might take the length of time it takes you to drain the desired amount of water out of your tanks to get it to the right temp, but you'll need to try it to find out for sure how long.

Solution #2, for chloramine treated tap water. Just use a really good water conditioner such as Seachem Prime, or Kordon Amquel+ with Kordon NovAqua+. These products disassemble the chloramine into its separate components of chlorine and ammonia, and then remove the chlorine and detoxify the ammonia so that it is safe for your fish.

Here's a little info on those products.

Don't alter their temps. It can stress them, make them susceptible to things such as ich, as well as other nasty things.
  • #30
Yeah, Prime will solve all your problems. I <3 prime.


  • #31
I was misinformed about chloramine it appears.

The bathtub idea is totally great by the way. I wouldn't have thought about that myself.

The fishies are totally getting a water change in the morning then. The ammonia is getting high. No signs of changed behavior but I've had just about enough of sick, dying or dead fish. I'm gonna nip this one in the bud before it gets out of hand.
  • #32
You could also get a 5 gal bucket and preheat it overnight with a 50watt aquarium heater. Might cost $20 at the most.
  • #33
Good luck dealing with the ammonia Illinest. I've read some of your posts and in general it sounds like you know how to handle it so... happy water changing!
  • #34
Good morning,

I had to heat water jugs for many years. I used the kitchen sink and the hot water set at 120 degrees. 4 jugs of cold water only took a few minutes to warm to 80 degrees. As Toosie mentioned, be sure to shake the jugs from time to time due to the fact that heat rises, shaking the jugs will help you to get a more accurate temperature.

If you have a spare tank and room to set it up, perhaps you can use it to preheat, treat and prefilter your water for your water changes. Then you can use a mag drive pump to pump the water from tank to tank or possibly just siphon it from tank to tank. See thread below:

The above might make your water changes a bit more fun, less work.



  • #35
Here is what I have discovered about temperature over the years. Fish normally do better in the upper range of their particular temperature spectrum so keeping them in the lower range all the time isn’t a good idea. One way that a lot of fish-keeper get egg layers to spawn is to slightly lower the water temperature in the tank over a 24 hour period which makes the fish think that the rainy season has arrived which is their normal spawning season. You wouldn’t be able to simulate this seasonal change if your tank is always kept at the low end of the temperature range. This isn’t as much of a big deal with livebearers but it does seem to slow down their gestation period so if you are planning on breading you will be slowing down how long it takes for the fish to give birth. One last note on temperature is if it is already on the low side and you have a power outage your tanks temperature could drop very quickly into the danger zone and kill your fish.

So what I am trying to say here is I would advise against keeping your tank at such a low temperature.
  • #36
Update. The temp only went down a few degrees and I found all the guppies huddled up near the heater. I felt like a heel and raised their temp back up. The tub warming method worked beautifully.
My ammonia readings aren't so great. Just shy of 4 ppm prior to change. Slightly under 2 ppm after. I think I may be overfeeding after seeing the crud that got kicked up when I was adding water back in. Still happy to report that the guppies are showing no signs of distress but I want to get their water right.
Whats the best vacuuming method? My tank is in an upstairs bedroom about forty feet from the nearest sink. Id prefer not to run water hoses like I saw on the python website.
  • #37
  • #38
Yep, just get a couple of 5 gallon buckets so you can pop the hose from one into the other quickly. You can also buy this bucket clip for the syphon hose so that you don't have to worry about the hose popping out of the bucket, and you can use it to slow dow the syphon and virutally stop the flow when you need to move the hose from one bucket to the other.

I've also used this little doo-hicky to start the syphon, in case you ever have problems with that. Just put the nozzle into the aquarium and pump the bulb to get water into the hose, put your thumb over the end and move it to the pail, OR I also found if you put the nozzle against your arm and squeeze the bulb, it worked well to start the syphon too. Fastest and easiest is to start off with a little water in the pail, place the nozzle into it, and pump the bulb once or twice.


  • #39
Wait a minute. You use a siphon hose to vacuum?!? Does that even make enough suction?
  • #40
Yup, works great. But it's not just a hose. It is a hose connected to a plastic tube. Then you just push the tube down thru the gravel to the bottom of the tank, lift ou move over a little push to bottom etc.

I got my gravel vac at PetSmart, and it came with a bucket clip so there was no need to buy one seperatly.
  • #41
I use a 65 gallon trash container to preheat my water{200 watt}to 78 degrees in my basement.I have a sump in there with a 60 ft hose to fill the tanks.
  • #42
Illinest, why not use treated tap water? It would be so much easier than heating containers of water. If the spring water has a different pH, you would have to acclimate the fish the first time, but after that it would make things a lot easier.
  • #43
I get a box with gallon jugs of spring water, 6 of them, delivered to my front doorstep on a pretty regular basis.
Suuuuuuure I could drink it but I've always used it for my fish before. This was my first water change with tropical fish so I just did what I was used to without thinking about whether it's the easiest thing or not.

I must say that the bathtub warming method turned out to be pretty easy overall. I think I might alternate until I decide which I like better. I think that for my situation they'd end up being pretty equal when all is said and done.
  • #44
Because the water chemistry between the spring water and your tap water is likely very different, that is, different hardness, different buffering capacity, different total dissolved solids, different pH, you'll want to be careful how much water you change out at a time if you want to try using your tap water. Do a very small water change when you try it. If you decide you like using your tap water, do more small water changes everyday for a few days to get the fish used to the tap water, and then you can start increasing the amount you change and go back to your regular routine.
  • #45
Update and new question:
I got my vacuum and did a cleaning. Looks better. Been feeding less. Changing water. Ammonia still present but its down below 2.0. I also wanted to address the fact that my filter is only rated for ten gallons so I figured rather than buy a new one I could just hang two filters. I had one left over from my last tank. I also figured that it would make it easy to clean the filter bags without losing my bacteria.
My question then - is it possible to have too much filtration?
  • #46
No, it is not possible to have too much filtration...but you can get too much current. Of course you'll know there is too much current if the fish are being tusseled about by it.
  • #47
Yep, just run em side by side if you have the space. And only rinse your filter bags and don't replace them unless they are falling apart.

2.0 ammonia is dangerously high...I don't remember and am too lazy to re-read the thread, but if it wasn't brought up already be sure to use Prime or AmQuel to nutralize that ammonia, and frequent water changes.
  • #48
I just bought some Prime but I also just put more Tetra SafeStart in the tank. The TSS is supposed to be replenished if you do a water change, which I've done a few times this week. If Prime neutralizes the ammonia then what happens to the bacteria that lives off of the ammonia? I want to get rid of the ammonia but I don't want to kill my bacteria.

"You can test the water any time, but really, you should probably wait at
least 48 hours. We expect TSS to start slowly seeding the tank, and
making a difference in about that time. You have to have some ammonia
occur in the tank to provide the cycle needed, so it will usually create
levels or reduce levels to around 1.0-1.5 ppm, and they should stay
there for a week to 14 days, and then come down. Sorry, these levels
would be for both ammonia and nitrite. These are considered stress, but
not toxic, levels, and should not cause any long term damage to the

We recommend waiting two weeks before a water change. Of course, if for
some reason, the levels go up to a high level again, we would recommend
a change at that point, and another dose. Usually, the hobbyist has
done something wrong the first time, in such cases."

This describes my situation pretty well. It's from the TSS Q and A
  • #49
Prime doesn't kill the ammonia...It neutralizes or masks it safe for the fish but it still feeds the nitrite and then nitrate.

Everything I've read TSS doesn't work and there is no way that I would wait 14 days to make a water change with ammonia at 2.0.

Also, from my personal research of store shelve, TSS is usually way past the expiration date. But furthermore how can bacteria in a bottle stay alive without being fed and suffocated...Especially past the exp date? I don't know, maybe it will fertilize a fish-less cycle. I just don't see how it can be anything more than "fertilizer".

Ask your LFS if they can supply some cycle filter media.
  • #50
I don't have a whole lot of experience with the bacteria in fish tanks but I was pretty interested in brewing beer for awhile and I think there are some useful parallels. Yeast is not a bacteria of course but they do operate in similar ways. Yeast I know can go dormant, and I believe that the TSS bacteria is probably dormant in the bottle as well.

In a beer for example the yeast converts the complex sugars and creates alcohol until the alcohol content gets high enough to shut down the yeast's ability to convert. Your Nitrosomonas (according to Tetra) aren't effective in converting ammonia to nitrites when the concentration is greater than 4.0 ppm. I don't know that the process is exactly the same for bacteria as it is for yeast but it sounds very similar to me. As another example - consider the packets of dry baker's yeast that you can buy at the store. There's no water or air or anything in there but as soon as you add water those yeasts rehydrate and are ready to grow.

The TSS isn't dead bacteria or else there'd be no point in adding it. More likely it's bacteria that was made dormant by putting it in solution with its' 'food' in concentrations great enough that it can't make conversions while in the bottle. If that's the case then it may stay effective inside the bottle for an indefinite period. When the bottle is poured into the water the ammonia is diluted and the TSS bacteria can begin to grow.

I do have to admit that I'm not experienced enough to say that TSS works or doesn't, but I know that a chemical like Prime is only going to be a temporary fix. It won't tell me what I originally did wrong to get elevated ammonia levels. So far I'm thinking that it did work at least a little, because this tank never got cloudy like any of the others I've done, and the guppies never went through the 'barely hanging on' phase that I used to see when I was just starting out.

If the levels weren't consistently going down then I'd definitely say 'screw TSS' and protect the fish from the ammonia. I really think that I was the problem however. I am certain that I was overfeeding. If not for my overfeeding I think I would already be telling you a TSS success story.

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