In a newly cycled tank how long can I go before fish need to be added

BaldAndBeard · Jan 4, 2024

Greetings,

I've been searching on this topic for a bit, and I have found a few rough answers, but looking for a bit more guidance/advice. Situation is I am about to start cycling my new tank. I know the process for this, so I think I'm well prepared in that regard. However, I have some family things coming up and then it will take a couple of weeks to get a couple clownfish as well once I'm ready for them. So, I just have no idea when I'll be able to actually get the fish and add them to my tank. Say I have my tank cycled, how long can I wait before I need to start adding fish, and what are the steps to fill that gap to simulate the bio load the new fish would create in the meantime?

So, it is a bit of a different question than usual, I'm not looking to add things as quickly as possible, rather how slow I can go, lol.

Appreciate any advice here. Just don't want to go through the whole cycle process and then screw something up because I waited too long to add any livestock.

rhitee93 · Jan 4, 2024

You can wait as long as you want. The bacteria you build up during the initial cycle don't starve. They'll just be waiting patiently for your first fish to go in.

brandon429 · Jan 4, 2024

Agreed. If you cycle a tank, then leave it fishless for five years it's still cycled and you can put fish in when you want. Water bacteria cannot be starved in an open topped home tank, feed is always getting in via trace means 24x7

ErikVR · Jan 4, 2024

The best advise I can give you is, patience is key in this hobby.
In my experience... If you find yourself asking how fast you can do this or that, you need to take 3 steps back

Just follow the steps on the starter bottle you use.
Your answer to how long it takes: when ammonia and nitrite is gone.

No need to worry about bacteria staying alive for a couple of weeks without additional bio load.

tomtheturkey · Jan 4, 2024

BaldAndBeard said:
Greetings,

I've been searching on this topic for a bit, and I have found a few rough answers, but looking for a bit more guidance/advice. Situation is I am about to start cycling my new tank. I know the process for this, so I think I'm well prepared in that regard. However, I have some family things coming up and then it will take a couple of weeks to get a couple clownfish as well once I'm ready for them. So, I just have no idea when I'll be able to actually get the fish and add them to my tank. Say I have my tank cycled, how long can I wait before I need to start adding fish, and what are the steps to fill that gap to simulate the bio load the new fish would create in the meantime?

Appreciate any advice here. Just don't want to go through the whole cycle process and then screw something up because I waited too long to add any livestock.

So depending on if you used live or dry rock will be a little different on the answer.

If live rock it has bacteria on it and bacteria is already there and you can feed a small amount of fish food to the tank that will break down to ammonia and feed the bacteria.

If its dry rock I would feed the tank once or twice a week and just start testing the water.

If you are using the bacteria in the bottle Like Fritz turbo or Dr Tims combination of the above will be more than ready for a couple of clownfish whenever you are ready. Just add the bottle the day of fish addition

But I agree with others it will always be there I just add fish food to keep the bacteria growing and building for peace of mind so a little feeding here and there isnt going to hurt

jda · Jan 4, 2024

It is well publicized and researched fact that Ammonia Oxidizing and Nitrite Oxidizing heterotrophic Bacteria do indeed die off from lack of things to process, but they also quickly multiply once needed. A few weeks is likely nothing to worry about in any case.

In a new tank, AOB and NOB are likely all that you have. In a more established reef, there are more types of consumers for fish waste that are less likely to die back. Most folks don't even understand that processing fish waste shifts from AOB/NOB to more direct consumers over time.

I have a small 10g QT for fish if I ever need to treat them. It has a HOB filter and sponge filter. I can run at 0.00 or 0.01 ppm of nh4 on Hannah digital for months while fallow. If I put a fish in there, the ammonia can get to 0.15 or 0.20 while the bacteria multiply. These numbers are not a concern to me and I can change some water if I care. In a day or two, the numbers are back down again.

Here is all that you need to know about the starting a tank. First, any method or technique to start a tank will work if you are smart and go slow enough - any method can be safe but also any method can harm the first inhabitants if you are too hasty. Second, the cycle never ends - it is cyclical like the name cycle implies and the tank will always be expanding and contracting certain things as things change. You can enjoy your tank and have fun with it as it matures and continues to develop over time, just know where you are at in the process and know that nothing is ever truly done.

twentyleagues · Jan 16, 2024

jda said:
It is well publicized and researched fact that Ammonia Oxidizing and Nitrite Oxidizing heterotrophic Bacteria do indeed die off from lack of things to process, but they also quickly multiply once needed. A few weeks is likely nothing to worry about in any case.

In a new tank, AOB and NOB are likely all that you have. In a more established reef, there are more types of consumers for fish waste that are less likely to die back. Most folks don't even understand that processing fish waste shifts from AOB/NOB to more direct consumers over time.

I have a small 10g QT for fish if I ever need to treat them. It has a HOB filter and sponge filter. I can run at 0.00 or 0.01 ppm of nh4 on Hannah digital for months while fallow. If I put a fish in there, the ammonia can get to 0.15 or 0.20 while the bacteria multiply. These numbers are not a concern to me and I can change some water if I care. In a day or two, the numbers are back down again.

Here is all that you need to know about the starting a tank. First, any method or technique to start a tank will work if you are smart and go slow enough - any method can be safe but also any method can harm the first inhabitants if you are too hasty. Second, the cycle never ends - it is cyclical like the name cycle implies and the tank will always be expanding and contracting certain things as things change. You can enjoy your tank and have fun with it as it matures and continues to develop over time, just know where you are at in the process and know that nothing is ever truly done.

I'm glad someone besides me said this. I have just returned to the hobby 1 yr and have read stuff here that is so far off of what I knew/know that I'm astounded. I get it things change but how does something that is/was 99.9% true and known do a complete 180 in 14yrs? Bacteria dont die off, lol they sure do! The bacteria population will expand and contract according to bio load. If you completely cycle a tank with 2.0ppm of ammonia the bacteria will be able to handle 2.0ppm of ammonia in a given time frame if you load in 4.0 ppm of ammonia you are going to have 2ppm leftover until the bacteria population grows. Which could be detrimental/deadly to those producing the ammonia. ( I just put numbers in dont quote them its not that simple)
OP you will still have a cycled tank for weeks but add your fish slowly dont go get 2ppm worth of ammonia producers as soon as you get back. (that'd be quite a lot of fish and again numbers added for effect)

CKW · Wednesday at 9:09 AM

Go slow and enjoy every step. I know it’s difficult at times but do it anyway! You will thank yourself later.

BeanAnimal · Wednesday at 9:22 AM

twentyleagues said:
I'm glad someone besides me said this.

Almost everybody understands this, save a few members of this forum who think they can redefine "science" for whatever reason.

The "cycle" itself is never "done" unless it denotes initial "seeding" of each tier of nitrifying bacteria. From that point forward (barring any massive damage) those populations will expand and contract based on availability of food.

They can fall out of equilibrium due to chemistry or other changes, but typically this is a result of adding substantially more food than they can process at their current population levels. So tossing a fish or two in an idle 75 gallon tank and feeding them is not a problem. Tossing a dozen fish and inverts into an idle system and feeding them may result in an ammonia spike as the bacterial consumer populations take time to catch up.

Cell · Wednesday at 9:34 AM

The hand wringing over semantics and subsequent sniping around here is exhausting. Bacteria may die off, but not all of it such that in practice, you should not need to feed to maintain a bacterial population which is the question. It may not be as robust, but you shouldn't have to go through the cycle process again. And yes, the cycling may never technically be done, but for our intents and purposes, ie what actually matters to us, we use the term "cycled" to say a tank is ready to support livestock.

Cell · Wednesday at 9:41 AM

BeanAnimal said:
Almost everybody understands this, save a few members of this forum who think they can redefine "science" for whatever reason.

Not sure what you mean by "redefine science" but science is all about redefining our existing or preconceived notions based on evidence or observations. It's not static or permanent. But nice dig.

BeanAnimal · Wednesday at 9:43 AM

Cell said:
The hand wringing over semantics and subsequent sniping around here is exhausting.

And here you are sniping.... pot meet kettle. You basically repeated what I and a few other said and threw your own jabs in. Come on man, notice the glass house that you are throwing rocks from once in a while.

Cell · Wednesday at 9:45 AM

BeanAnimal said:
And here you are sniping.... pot meet kettle. You basically repeated what I and a few other said and threw your own jabs in. Come on man, notice the glass house that you are throwing rocks from once in a while.

lol. Ok bud.

Garf · Wednesday at 9:49 AM

Cell said:
The hand wringing over semantics and subsequent sniping around here is exhausting. Bacteria may die off, but not all of it such that in practice, you should not need to feed to maintain a bacterial population which is the question. It may not be as robust, but you shouldn't have to go through the cycle process again. And yes, the cycling may never technically be done, but for our intents and purposes, ie what actually matters to us, we use the term "cycled" to say a tank is ready to support livestock.

I know @MnFish1 has done something on this topic, I believe under starvation of ammonia for 2 or 3 months. Not sure anyone will do a 5 year test though, lol.

BeanAnimal · Wednesday at 9:51 AM

Garf said:
I know @MnFish1 has done something on this topic, I believe under starvation of ammonia for 2 or 3 months. Not sure anyone will do a 5 year test though, lol.

If I remember there were some unaccounted for variables (no way to determine how much residual food they would have had), but the general results indicated that the bacterial colonies were rather resilient over that time period.

Cell · Wednesday at 9:53 AM

BeanAnimal said:
Almost everybody understands this, save a few members of this forum who think they can redefine "science" for whatever reason.

There were no hostilities in this thread, everyone was just giving there own opinion until your comment here clearly directed at one individual. Calling that out is not the same. You are simply starting the same fight that has taken over many threads already. The comment added no value whatsoever to your post.

If you are going to PM people talking about being better people, then maybe practice what you preach.

brandon429 · Wednesday at 10:05 AM

I don't know how bean is allowed to wreck all these threads, he must be immune to correction.

You can't starve a cycle in a home setting. so, if you waited five years to add a bioload absolutely nothing would change. Bacteria get food from a home setting we don't add, especially when in a puddle of water heated swirled and with strong reserves and insulated bioslicks in place from the initial cycle.

I say this due to multiple work threads I was in where we directly tested starvation from rock fallowing, and found no starvation occurs.

Bean's presence is only to bring arguments, but if anyone wants to see my examples of non starvation I have dandelion's two year fallow test before he added bioload, ammonia was reduced overnite like any cycled tank, and DJCIty's three year testing of fallow live rock sitting in his garage.

I will message anyone who wants to see the examples, I'm not providing links for Bean to go over there and wreck those same threads. legit interested parties can see them.

DJ's tank handled ammonia after three years sitting just in uncirculated water. Dandelion's example was fully cycling a dry rock nano, testing it to prove readiness, then not using it for two years. when he stress tested it, it passed in 24 hours just like a normal reef

who cares if the bac go dormant then wake up, the point is, they're able and can't be starved

Garf · Wednesday at 10:11 AM

brandon429 said:
I don't know how bean is allowed to wreck all these threads, he must be immune to correction.

You can't starve a cycle in a home setting. so, if you waited five years to add a bioload absolutely nothing would change. Bacteria get food from a home setting we don't add, especially when in a puddle of water heated swirled and with strong reserves and insulated bioslicks in place from the initial cycle.

I say this due to multiple work threads I was in where we directly tested starvation from rock fallowing, and found no starvation occurs.

I don't remember these work threads, can you post a link? It must be a seneye tested tank that has not had the calibration sent out of wack by flawed calibration methods, obviously.