When moving fishes to a new tank, can I simply re-use all water of the old tank?

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kachibi

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I am raising some koi fishes (freshwater ones) and I will have a new tank very soon. So, I am going to move the fishes from the old tank to the new tank. The sizes of the tanks are similar.

So, I know the first thing to do is to fill up the new tank with new, salty water and leave the water there for at least one day. This step is to ensure the tank does not leak and to sanitize the tank ( the use of salt to eliminate toxic substances of the new materials like the glass and the glass glue).

So, after this 1 day, I withdraw all salty water from the new tank. I guess some people may then fill up the new tank with new water (and perhaps mix it with some water from the old tank), and then start the series of letting the air pump and the filter run, adding dechlorinator, cycling the tank, etc. for few days, before putting fishes in.

Assume that I will re-use all the equipments (the filter, the air pump, etc.) in the new tank. And now I decide to simply relocate all the old water to the new tank. And my old water is safe (which is cycled in the old tank, and the fishes are alright with it). So basically the difference is just the tanks. Can I skip the "pouring in new water then start the series of running the air pump, the filter, dechlorinating, cycling, etc." hassle in the new tank before putting the fishes into it?
 
I asked a similar question a week or so ago and just had to try it and pray .... week later all still alive water chemistry is fine , I started by getting the tanks half and half by using my old tank water I then put all my slate big wood and plants out of the old into the new , I used new gravel and sand , I then collected my 20 fish and put them in the new tank I then rushed to put my air stones and filter on then used as much of my old water as possible , worked for me don’t want to recommend that method as I’m sure there are others with better ways
 
Yes, I will use the same filter (so the bacteria as you said are in it), so no problem on the whole right with the old water, right?

And I don't have other things like wood, slate or plants.
 
I would just use new water. Bacteria lives in the filter and on your slate, wood and plants, not in the water.
That's the way I have always done it.

This.

Just treat your new water as you would a WC. Otherwise, as stated, the majority of your BB lives in your filter. You might have a bit of a mini cycle, but you should be golden with just a little extra maintenance. Just keep an eye on your parameters and respond accordingly.
 
Do you mean I can relocate (and hence reuse) the filter and other things like the air pump to the new tank. But never re-use the old water, the water must be new. And then just simply cycle the new water with the old filter?

First (hope someone can answer one by one), the above is yes/no?

Second, if yes, if I cycle the new water with the old filter (where bacteria lie), since all bacteria are there already, I guess certain steps are not needed? Please someone provide the steps (days needed included) of the process.
 
Do you mean I can relocate (and hence reuse) the filter and other things like the air pump to the new tank. But never re-use the old water, the water must be new. And then just simply cycle the new water with the old filter?

First (hope someone can answer one by one), the above is yes/no?

Second, if yes, if I cycle the new water with the old filter (where bacteria lie), since all bacteria are there already, I guess certain steps are not needed? Please someone provide the steps (days needed included) of the process.
Basically, when you're cycling a tank, you're not treating the water itself as such- you're building colonies of two different nitrifying bacteria. One type eats ammmonia and converts it to nitrite, the other eats nitrite and converts it to the much safer nitrAte.

That is what we're doing when cycling a tank. Creating a food source and surface area (the media in your filter) for those bacterial colonies to grow. They don't live in the water column, they live in the filter and on surfaces like the glass, the substrate, decor etc. So say you have a brand new tank, and a shop sells you their old tank water "to help jumpstart the cycle". This is next to useless, since the water isn't where the bacteria live. A bit of filter media or substrate however, can help. You then have a small amount of the right kind of bacteria, and the colony can grow to meet the demands of your tanks bioload.
 
Do you mean I can relocate (and hence reuse) the filter and other things like the air pump to the new tank. But never re-use the old water, the water must be new. And then just simply cycle the new water with the old filter?

First (hope someone can answer one by one), the above is yes/no?

Second, if yes, if I cycle the new water with the old filter (where bacteria lie), since all bacteria are there already, I guess certain steps are not needed? Please someone provide the steps (days needed included) of the process.
You can use some of the old water if you like. It's just not needed. If you haven't done many large water changes or you're switching to a new water source (say, switching from hard tapwater to RO water, then saving the water would make sense, as that would be too big a change in water parameters for your fish, too fast. If you were changing the source water, doing it in stages over a number of days/weeks would give the fish time to acclimatise. But if you've always used tapwater in your tank and are continuing to use the same water, then no need to save old water. You're basically just doing a 100% water change.

Just set up the new tank, substrate, water, decor, plants etc. When you're ready to move the fish, turn off the filter and airpump etc, move them to new tank, catch fish and move them over too.


Do your water tests more often at first, because you'll be losing the bacteria that were living on the substrate and surfaces of the old tank, but it won't take long for the bacterial colonies in your filter to catch up. So just keep an eye on ammonia/nitrites/nitrates, and be prepared to do a water change if ammonia or nitrites spike.
 
@AdoraBelle Dearheart
The reason why I prefer using the old water is because if I use the new water, I have to do those cycling things for 2-3 days. Because of geography, I have to relocate the fishes to a bucket or other kind of container (instead of keeping them in the old tank, since we don't have space at home). So if I have to cycle the new water in the new tank for 2-3 days it means the the fishes will be in the bucket or other container for 2-3 days, which is pretty dangerous I think--jumping out. Having a big bucket/ other container also means much space is taken up in the room.

So that's why I come up with relocating the old water to the new tank--since I can save the time of cycling new water in the new tank--and hence avoid keeping the fishes in another space-consuming and potentially dangerous container for the same period of time.

What do you think? Unless you tell me I also have to cycle the old water for few days in the new tank, so the things above are inevitable then I have nothing to say.
 
There are virtually no bacteria in the water as they live in the biofilm which is tightly bound to every surface in the tank. As long as the filter and as much decor as possible is moved, you can use all new water.
Cycling is the process of growing these bacteria, but you already have them in your filter and on your decor. Running a tank for 2 or 3 days is not cycling, it's just running a tank which is not necessary.
When you do a water change do you run tap water, add water conditioner and put it straight in the tank? You do not let the new water sit for 2 or 3 days before adding it to the tank? Moving the fish to a bigger tank with all new water is just like doing a very large water change.



The only time using old water is preferable is when the tank has been neglected so that the tank water chemistry is very different from tap water. But if the tank has been properly maintained - large weekly water changes - the tank water will be almost the same as tap water.
 
@essjay
When you do a water change do you run tap water, add water conditioner and put it straight in the tank? You do not let the new water sit for 2 or 3 days before adding it to the tank?

I normally just minus 1/3 of the tank's water (which was originally tap water) and add in 1/3 new tap water, yes, with adding in dechlorinator and some nitrifying bacteria. But I don't let the treated water sit for 2-3 days before pouring it to the new tank. I just do all steps at once. The fishes are fine with it.

So now, can you confirm the following steps are alright:

1) I soak the brand new tank with salty water for 1 day to ensure sanitation and no leakage.

2) Then, I dispose all salty water in the new tank.

3) I install the old filter and other old equipment in the new tank. And I pour new water in it. No other steps (like cycling, running the new tank, etc.) that will take more than 1 day are needed here right? As for the old tank and fishes, due to lack of space (cannot accommodate two tanks at the same time), I move the old water plus fishes to a bucket. So, if someone can tell me no other steps take more than 1 day (like cycling, running the tank water, etc.), I can move the fishes to the new tank without waiting, and eventually dump the bucket and the old water and the old tank altogether afterwards.
 
I would get new water. You can never have to much fresh water.

If you have a filter in the pond, you can just add bb to it, and have an instant cycle.
 
As I said in my last post, running the tank with just water in is not cycling.

This is what I would do -
Get everything ready before you start. If using new substrate wash that before starting.
Test the tank by filling with salt water, then empty and rinse all the salt out.
Siphon some old water into at least one container. Put any decor into a container of old tank water. Catch the fish and put them in the same container or a different one and make sure it is covered even if it's just with a towel. Put the filter in a container of old tank water, if the whole filter won't fit put the media in the container. If you will be using the same substrate, scoop that out and put it in a bucket
Empty the old tank and move it out of the way. Clean it up later.
Set up the new tank. If you are reusing the substrate it will be dirty so wash it with dechlorinated water so you don't kill the bacteria which live in there.
Fill the tank with new dechlorinated water at the same temperature as the water in the container with the fish.
Set up the old filter in the new tank.
Move any decor you are reusing into the new tank.
Catch the fish and put them in the new tank.

If you have bottled bacteria you may as well add it, but once you are sure ammonia and nitrite are staying at zero you don't need to use it again.



There is only one reason for leaving a tank to run 2 or 3 days and that is if you don't use water conditioner. In the days before water conditioners were invented, chlorine was always added to mains water to disinfect it. Letting water stand for 2 or 3 days allowed this chlorine to gas out of the water so it was safe to use. Nowadays a lot of places use chloramine instead of chlorine and this does not gas out so a water conditioner has to be used. Even in places where chlorine is used, it is quicker to use a water conditioner rather than have water standing round for days.
 
@AdoraBelle Dearheart
The reason why I prefer using the old water is because if I use the new water, I have to do those cycling things for 2-3 days.

No, you don't. Again, you're talking about cycling water. We don't cycle water, because a cycle is referring to the nitrogen cycle, the beneficial bacteria that live in the filter/on substrate/on surfaces. Your current tank is already cycled, and it has nothing to do with the water. It is the bacteria in your filter that process the fish and food waste that begins to accumulate in the water your fish are in, but those bacteria do not live in the water itself. You're going to be adding fresh, clean water, just as you would with a water change. This has not yet been pooped in and had a lot of food in it, so it should have almost no ammonia/nitrates/nitrates in it yet. (some tap water has some levels of these, but that's what declorinator and your already cycled filter is for, and since you use it in water changes immediately without problems, yours is likely fine).

We don't cycle the water. Your fresh tap water doesn't need to sit for days running though the filter "to cycle". Cycling is about building the bacteria in your filter, not about processing the water itself exactly, just ensuring that you have the bacteria colonies in your filter grown enough to eat the ammonia and nitrites that your fish produce once they are in the water. Running the new, fresh, declorinated water through the filter for days before adding fish is not needed.
@essjay
I normally just minus 1/3 of the tank's water (which was originally tap water) and add in 1/3 new tap water, yes, with adding in dechlorinator and some nitrifying bacteria. But I don't let the treated water sit for 2-3 days before pouring it to the new tank. I just do all steps at once. The fishes are fine with it.
As @essjay just said while I was typing out this essay, you don't need to wait and leave fish in buckets. Treat it like a really large water change, and add nitrifying bacteria this time, but you can move everything over, including fish, in the same hour even, no need to wait for days, and in fact, would be risky to leave the fish in buckets for days without the filter.

You don't need to add nitrifying bacteria at every water change. Again, the bacteria don't live in the water. The ones you add go straight through the filter, and by now, your filter should already have a large enough colony to handle the bioload your fish produce. The colony grows and shrinks according the amount of waste your tank/fish produce. If you're adding more new fish to the fish you already have, it can take a few days, but the bacterial colony will grow in order to handle the additional ammonia/nitrites produced, as long as there is enough surface area in the filter for them. This is why it's always recommended to add fish to a new tank in small batches, and to test levels and do additional water changes when first establishing a tank. Adding them in small groups over the course of a couple of weeks gives the bacterial colonies a chance to grow and catch up in order to safely process the additional bioload.

In your case, your filter has been running with your number of fish in it for a long time, and the colony is already large enough that you say your ammonia and nitrites are at zero. That's great. So no need to add more nitrifying bacteria at every water change, your colonies of bacteria already have it under control.
 
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Thanks:D. All my doubts are cleared:good:. Thanks for all, especially the last few forum users.

By the way, just a side question: if I am to add nitrifying bacteria to the tank, you guys say they don't live in water, where should I add them to? Directly to the filter media, the filter pad, or where?
 

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