# How Long For a New Filter to Cycle in a Cycled Aquarium?



## Raymond S. (Dec 29, 2012)

Two weeks. Take out a small piece of the old media from the old filter and put it in the new. After the two weeks(if you actually want this to be "seamless"...it won't be completely but as close as possible) start taking out the old filter media about 20% at each time you do it over two more weeks. The filters will develope equal amounts of bio bacteria at first. Taking out small amounts will force the new one to grow additional bacteria till it has the full amount needed when you remove the old filter on the last time you take some of the media out but instead just remove the filter.
I had a high stocking level in a tank and removed 20% of the media once to rinse it and forgot to put it back as I got distracted. By the next day I had several dead shrimp.


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## Diana (Jan 14, 2010)

Ditto Raymond: 
If you can share any media that will instantly transfer the bacteria. 
By removing the Tetra media a little each week for several weeks the transition will be as smooth as possible.


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## BBradbury (Nov 8, 2010)

*Switching Filters*



goodbytes said:


> I've replaced my old Tetra 30/60 HOB with an Aqua Clear 70 and I've got them both running now so I can seamlessly transition from the Tetra to the Aqua Clear. How long do you think it would take for the new filter to colonize so I can remove the old one?


Hello good...

Run them both for a couple of weeks. Then, you can remove the old filter. You have plenty of back up bacteria on the surfaces inside the tank. What you remove when you take away the old filter will reproduce to former levels in a few hours.

B


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## Diana (Jan 14, 2010)

> ... will reproduce to former levels in a few hours


No, they won't. Nitrifying bacteria are slow growing compared to many other bacteria.


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## Briggadane (Apr 28, 2014)

Keep in mind, you got the answer to the question you asked. I suspect you really want to know: how can I quickly seed my new filter so I can remove the old one ASAP. 
&#55357;&#56841;


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## goodbytes (Aug 18, 2014)

Briggadane said:


> Keep in mind, you got the answer to the question you asked. I suspect you really want to know: how can I quickly seed my new filter so I can remove the old one ASAP.
> ��


Yeah, I definitely should have been more clear. My intention is just to run both without tampering with either until I can simply unplug the Tetra and store it. I'm going to give it a month and hope I don't have any sort of cycling--which I shouldn't as I also have many plants and a sponge filter. It would be nice if I were using a custom media that I could just transfer over but unfortunately the black bio sponges that come with the large Tetra filters are tall and narrow and just don't lend themselves easily to being stuffed into the Aqua Clear.


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## wendyjo (Feb 20, 2009)

Can you cut up the old sponge and put peices of it in the new when it's time for the final transition?


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## goodbytes (Aug 18, 2014)

So I just ended up using safety pins to bend one of the bio sponge in half and jammed it in among the layers of Aqua Clear filter elements. Hopefully that'll speed things along.


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## Diana (Jan 14, 2010)

It will. 

Just have to think of it this way:

No matter how many tanks you have, how many gallons, how many filters... it does not matter. 

If you have F many fish, then you have F x 1,000,000 bacteria. 
It does not matter how much bio media you have, or where it is located. If the water from the fish flows through the media, the bacteria will grow there. But only enough to match the waste load of the fish and other organisms in that tank. 

But if you had M amount of media, now you have M x 2 media, then each bit of media will only have half as much bacteria, as long as you keep the same number of fish. You are not GAINING any bacteria, just spreading it around. 

When you remove the extra media to another tank, you are shorting the established tank of that population of bacteria. 

This may not be so important in a thriving planted tank, the plants do a lot of the work. But I would still watch out for ammonia and nitrite spikes when you remove the second filter media. 

Better: 
Just run the 2nd media long enough to get a little bacteria growing, then put it on the new tank and complete the fishless cycle. 
Or, take up to 25% of the established media (any- sponge, floss, bio, even month old carbon) from the existing tank, and share that with the new tank to jump start the bacteria growth. I have shared a max of 25% of the established media, even from tanks with no plants, and the donor tanks were fine. 
Remember that 25% of the media in the filter does not mean I was taking 25% of the bacteria. There is a lot more bacteria on all the surfaces of the tank- the substrate especially. When I took a bit of the sponge, floss or bio media, I may have been taking 1/8 or less of all the bacteria in the tank. 
But that was plenty to jump start the next tank. 

I would take that much from several tanks, so the new tank was starting with perhaps 1/4 of a load of bacteria, then I would build up the fish population slowly. (This was before I had heard of the fishless cycle). 
I am still doing that concept today. Except that I am adding in the fishless cycle for uninhabited tanks. Gets them ready pretty fast. 

Just keep thinking about how much bacteria you have, and where it is. 
You can move it around, but you cannot grow more unless you set aside a tank without fish and feed the bacteria with ammonia or fish food.


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## roadmaster (Nov 5, 2009)

Diana said:


> No, they won't. Nitrifying bacteria are slow growing compared to many other bacteria.


 
Have read that the nitrifying bacteria can double through binary division in 8 to 24 hours.
Initially,yes they are slow to develop but once established, they can reproduce fairly quickly compared to other bacteria.

www.bioconlabs.com/nitribactfacts.html


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## Diana (Jan 14, 2010)

a) They have the wrong species.
b) They say their bacteria is slow to reproduce. Many hours compared to some bacteria that can reproduce as fast as 20 minutes (this is the group that causes cloudy water in a new set up).

See the second and third items in this link. The correct species of bacteria have been known for 10-15 years. That any aquarium company continues to market the wrong species is unethical. 
http://www.drtimsaquatics.com/resources/library-presentations/scientific-papers


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## roadmaster (Nov 5, 2009)

Diana said:


> a) They have the wrong species.
> b) They say their bacteria is slow to reproduce. Many hours compared to some bacteria that can reproduce as fast as 20 minutes (this is the group that causes cloudy water in a new set up).
> 
> See the second and third items in this link. The correct species of bacteria have been known for 10-15 years. That any aquarium company continues to market the wrong species is unethical.
> http://www.drtimsaquatics.com/resources/library-presentations/scientific-papers


Is good article as well, yes
I guess for me,,a few hours to reproduce compared to the weeks that it takes initially for nitrifying bacteria to develop a colony does not seem all that long.


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## Diana (Jan 14, 2010)

Look at how many times a colony needs to double to build a reasonable population, meaning a cycled tank: Takes 3 weeks under optimum conditions, starting with just the smallest starter colony, or depending on bacteria finding the tank (and they find it really fast; these bacteria are all around us). 

But look at how fast heterotrophic bacteria can create cloudy water: 
From start up (this first cloudiness is substrate dust settling) and within 24-48 hours the heterotrophic bacteria can be growing fast enough that the water looks a bit cloudy. This is somewhere around 100 'doublings' (20 minutes time to double means it doubles 3 times per hour, or 72 times per day. If the cloudy water shows up in 1-2 days that is between 72 doublings and 144)

For nitrifying bacteria to double that many times (using 16 hour doubling time) takes about 2 months. (mumble... mumble... 16 hours means 3 doublings in 2 days, to get 100 doublings needs 33 x 2 days...)

So...
Heterotrophic bacteria needs 2 days to double 100 times. 
Nitrifying bacteria needs 2 months to double 100 times. 
That is slow. 

Now, if you already have a big colony of nitrifying bacteria, and want it to double, that might go faster (a day), but faster than what? Faster than waiting for those same species to reach that population level starting from scratch. (a big colony of heterotrophic bacteria would have doubled by the time you got back from lunch)

Alternate method to start a new tank:
Divide an existing, well established tank this way: (assumes the tanks are the same size)

Old filter to new tank. 
New filter to old tank. 

Old tank keeps its plants, substrate, decor, but gets pruned to donate cuttings. 
New tank gets cuttings, and new plants. 

Half the fish stay in the old tank. 
Half the fish go to the new tank. 

What you have done is try to equalize the bio filter (plants and bacteria), and share the bio load (the fish) as equally as possible. 

Now, both tanks have smaller bio loads, and smaller waste handling ability, but both have a generous starter colony of bacteria and plants that can grow quickly to handle a full bio load. 

Give the two tanks a week or two to settle in, the plants to recover and start rooting. 
Then gradually add more fish to both tanks.


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## roadmaster (Nov 5, 2009)

Yes Diana,

We are saying the same thing (Me thinks).
We agree that to build initial colony of nitrifying bacteria takes far longer than it does for established colony to re-produce.
I tend to look at nitrifying bacteria as the many parts that make a whole.
Water from an aquarium looked at on a slide under the microscope ,would show many bacterium,microfauna.and tiny organisim's that all together make the whole .
Is why I never much cared for the term "Cycled aquarium" for it implies that at some point,the process is complete when in fact it is ongoing process where the many bacterium that make up the whole increase and decrease as needed to maintain the nitrifying process of oxidizing the ammonia created from excess food which is common along with adding fishes and waste produced by the fishes.
Bacterial colony shrinks a little bit if you will by reducing the organic input for the food that it feeds on has been reduced.
Once the sum of the many parts (bacterium) which helps create a Mature tank rather than merely a "cycled tank" has developed initially re=producing does not take long ,maybe a day or two.
If this was not so,,then it would reflect at the end of the Fishless cycling method that many folks use when they re-dose the water in the aquarium back up to four times the amount of ammonia a healthy nitrifying bacterial colony/fishes will ever see (hopefully).
I respect your views,and I know that this is all known to you. 
I'm not able to communicate effectively sometimes, but I struggle on in hopes that other's can maybe not have to.
I would add that a heavily planted tank which is three or four weeks old and plant mass is thriving ,that bacterial colony does not really become much of a player in my book for the plants are best at biological filtration.
Takes time to get the plants growing well and is what I try to do before introducing fishes into a newly established tank.
Silent cycling or Maturing if you will.


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## Diana (Jan 14, 2010)

I hear what you are saying and agree with it:
The "Cycle" we talk about the most is the Nitrogen Cycle. The growth of the specific organisms responsible for making ammonia and nitrite into nitrate. 

The concept of a 'mature tank', meaning the growth a many other micro and macro organisms is one that is not talked about much. You hear only passing comments such as "this fish needs a mature tank'. 

Many of the organisms that live under water also live out of the water, or at least can travel between bodies of water via air. 
When these organisms find themselves under water they will either thrive, sort of sit there, or die. While many many species are doing this, and arguing with each other about the real estate, the tank is not mature. 

Roughly it takes about a month for the most active of these organisms to state their case and settle down. It may take several months for little details to work out. 

In the mean time, that first month is also when the nitrogen cycle bacteria can grow a really good population, so following the fishless cycle is also allowing time for many other organisms (including plants) to get a good start in the tank. 

When there is a mature tank available, meaning an aquarium that has been running with fish and plants and they have been healthy for more than a month (and some people say as long as 6 month minimum) then that tank is a good source of many microorganisms, not just the nitrifying species. Sharing filter media or anything else from such a tank with a new tank will speed up the cycling (in all forms) of the new tank. If you share just a little bit of stuff, then the cycle is not sped up very much. If you share a lot, then all the organisms are getting off to a better start, so the new tank will cycle (nitrogen cycle) and become mature (all the other organisms) a lot faster.


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## BettaBlake89 (Jul 22, 2021)

goodbytes said:


> I've replaced my old Tetra 30/60 HOB with an Aqua Clear 70 and I've got them both running now so I can seamlessly transition from the Tetra to the Aqua Clear. How long do you think it would take for the new filter to colonize so I can remove the old one?


To me it's easy cheesy. You just leave both filter in there two weeks to a month. It honestly depends on your tank and the bio load it takes on on a daily basis. If you have a small bio load it may only take 2 weeks for you to have enough bacteria colonized. If you have a high bio load like in cichlid tanks, obviously it could take a month or more.


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