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Aquarium Science High School Class - Cycle Trouble


GoGreen
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Hello All.  I have just finished my second aquarium science class which has been a huge success overall.  I have had countless kids tell me that it was their favorite class they have ever taken and in 2 quarters, we have started 20 tanks that the kids have taken home.  All the success aside, we have had a little trouble cycling our tanks...or keeping our tanks cycle.  We are doing a fishless cycle over the entire course of the class.  We start in week 1 with the goal of starting with 4 ppm of ammonia solution that I make for them (using the ammonium chloride powder from fritz).  We test the water twice a week (we go through a LOT of test strips!), with the goal of stocking our tanks in week week 7 of the 9 week class.  Before the kids are allowed to purchase fish, they are required to show me that the tank has 0 ammonia and 0 nitrites and explain how they know the tank is cycled.  Every tank is a little different because some kids buy plants, some kids put in driftwood, decorations, etc, but the testing requirement before we get fish is the same.  So I know the tanks are cycled; at least initially.  The kids who cycle early, put in about .25 ppm of ammonia every testing day to ensure the bacteria stay alive.  

All of this prep work aside, both quarters when we have ordered fish and put them in the tanks, we end up with detectable levels of ammonia and nitrite in the tank, and some dead fish.  I have been racking my brain trying to figure out what might be going on.  An example...we have 10 gallon tanks with aquarium co-op sponges.  A student put 2 African dwarf frogs in yesterday afternoon and when she put them in, nitrates were between 0 and 10 ppm, with ammonia and nitrite at 0.  Today when she tested, nitrates were up to 25, nitrite was up to 5 ppm and ammonia between .5 and 1 ppm.  We obviously changed water and got those numbers back under control, but I cannot figure out why this is happening.  It is not an isolated occurrence.  Another group had 2 dwarf frogs as well and then 6 zebra danios (maybe 3/4 in long) and her numbers were almost identical. 

I cannot figure out what is going on.  I went through some of the usual culprits; neither fed their tanks at all so it isn't over feeding;  neither put in water from the shipping bags, our school is on a well so there is not any chlorine killing the bacteria.  Anyone have any ideas that I may have overlooked.   

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I think it may be b/c the bacteria only grow to the bioload in the tank. When you introduce fish/frogs etc, the bacteria needs time to reproduce up to those levels. The .25 ppm ammonia was just enough to keep things going, but for a very small bioload. That's why it's good to start off with a small bioload (even "pest" snails), and build it up slowly. Once your tanks become more seasoned, this becomes less of an issue - esp if you have plants helping things out. Your post-frog numbers show that the cycle is still working, but maybe that was a bit much of a bioload to start with. 

 

Edited by MattyM
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On 1/12/2023 at 11:26 AM, MattyM said:

I think it may be b/c the bacteria only grow to the bioload in the tank. When you introduce fish/frogs etc, the bacteria needs time to reproduce up to those levels. The .25 ppm ammonia was just enough to keep things going, but for a very small bioload. That's why it's good to start off with a small bioload (even "pest" snails), and build it up slowly. Once your tanks become more seasoned, this becomes less of an issue - esp if you have plants helping things out. Your post-frog numbers show that the cycle is still working, but maybe that was a bit much of a bioload to start with. 

 

On 1/12/2023 at 11:26 AM, MattyM said:

I think it may be b/c the bacteria only grow to the bioload in the tank. When you introduce fish/frogs etc, the bacteria needs time to reproduce up to those levels. The .25 ppm ammonia was just enough to keep things going, but for a very small bioload. That's why it's good to start off with a small bioload (even "pest" snails), and build it up slowly. Once your tanks become more seasoned, this becomes less of an issue - esp if you have plants helping things out. Your post-frog numbers show that the cycle is still working, but maybe that was a bit much of a bioload to start with. 

 

 

On 1/12/2023 at 11:37 AM, Darax said:

I'll second Matty* . Try increasing your virtual bioload during fishless cycling next semester. 

 

*except for the suggestion to use pest snails. 🙂

That makes sense and was where I was thinking, I just didn't believe it.  It seemed like adding that amount ammonia every 3 days would sustain more bacteria than a few small frogs that haven't eaten in several days (they were shipped to us); but that is anecdotal, so apparently that isn't the case.   Another tank in the same class, following the same methodology, has a betta fish and several guppies and they did not have any issues.  Everything stayed 0 in their tanks (and they brought the fish from home, so they had a full gut and everything).  

As I am tying all this out, I am starting to wonder if they were following the protocols.  It makes no sense a seasoned fish keeper like the student with the guppies would have complete success and the others would not.  Something I will have to ask/keep an eye on as a possibility.  

 

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This feels like a prime setting for a cycling experiment! Like put bottled bacteria in some, others get a handful of gravel, others get an old sponge squeezed into it, and then others are a control group.

But to actually be helpful... Do you monitor KH? Maybe the carbonate is getting used up in some of the tanks when they are cycling

I think what the others have said are good advice. Maybe increasing ammonia levels while in holding pattern. Or if you have an established tank you keep in the tank you could throw a few class guppies/mollies in the tank once they are "cycled" to help keep the bacteria alive and establish the tank more. That way you get the benefit of living stuff adding poop and whatnot without worrying about infesting everyone's tanks with snails. I personally like snails but I know that's not everyone's thing.

Doing cycling testing sounds like a good way to figure out cycling techniques while existing it as a way to teach scientific method... Let them hypothesize about what the best way would be

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On 1/12/2023 at 11:53 AM, Aiden Carter said:

Wait, your school system has an aquarium science class?!?!! I want one: (

Yeah, we were looking for electives last year and this was the one that I pitched and got approval for.  It is by far the most fun class that I have ever taught. 

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On 1/12/2023 at 8:54 AM, GoGreen said:

Another tank in the same class, following the same methodology, has a betta fish and several guppies and they did not have any issues.

Was there a difference in setup? Like substrate depth?

 

On 1/12/2023 at 8:53 AM, Aiden Carter said:

Wait, your school system has an aquarium science class?!?!! I want one: (

I second this. Feels like a good class too, think about how much science you learn when you really dig into how this work 

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On 1/12/2023 at 11:54 AM, Schuyler said:

This feels like a prime setting for a cycling experiment! Like put bottled bacteria in some, others get a handful of gravel, others get an old sponge squeezed into it, and then others are a control group.

But to actually be helpful... Do you monitor KH? Maybe the carbonate is getting used up in some of the tanks when they are cycling

I think what the others have said are good advice. Maybe increasing ammonia levels while in holding pattern. Or if you have an established tank you keep in the tank you could throw a few class guppies/mollies in the tank once they are "cycled" to help keep the bacteria alive and establish the tank more. That way you get the benefit of living stuff adding poop and whatnot without worrying about infesting everyone's tanks with snails. I personally like snails but I know that's not everyone's thing.

Doing cycling testing sounds like a good way to figure out cycling techniques while existing it as a way to teach scientific method... Let them hypothesize about what the best way would be

That is a good idea.  Maybe I will try something like that next quarter.  I have a bigger tank in the room and a tank with "class fish" for the students who aren't planning on buying their tanks.  

We do monitor KH.  Our water is harder than hard in our district.  So hard in fact, that the aquarium coop test strips turn a different color than is actually available.  With that, our buffer is usually in the 180+ ppm range.  

On 1/12/2023 at 11:57 AM, Schuyler said:

Was there a difference in setup? Like substrate depth?

 

I second this. Feels like a good class too, think about how much science you learn when you really dig into how this work 

Very minimal differences.  One used dark pebble substrate, one used light and they had slightly different amounts of driftwood.  1 tank that did well and 1 that did poorly had a few live plants, the other that did poorly used fake.  Other than that, the setups were identical.  

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With 2 juvenile goldfish in 20 gallons doing a fish in cycle (I didn't know what I was doing...) , ammonia was over 4ppm after two weeks. When I figured out my mistake, I did daily 50% water changes. IIRC it was still two weeks before the ammonia starting becoming nitrate (and another week or so for the nitrate to fall to zero and nitrites started climbing).

Not sure what load frogs and such put on a tank, but it does sound like it is higher than intuition suggests. 

Edited by Darax
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There are some interesting experiments discussed on aquarium science (.org) regarding cycling, showing whether "bacteria in a bottle" actually works, etc. If you haven't seen it, it may be worth a read through. I actually tried one of his methods, and cycled a tank in like 9 days. 

Edited by Bill
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On 1/12/2023 at 9:33 AM, Bill said:

There are some interesting experiments discussed on aquarium science (.org) regarding cycling, showing whether "bacteria in a bottle" actually works, etc. If you haven't seen it, it may be worth a read through. 

I was just about the mention that too. Although maybe getting students to add urine to there tank could land you in got water with the school board...

https://aquariumscience.org/index.php/2-aquarium-cycling/

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On 1/12/2023 at 12:34 PM, Schuyler said:

Although maybe getting students to add urine to there tank could land you in got water with the school board...

Yeah they should stick with the Ace hardware ammonia. I used Black Kow in a bio bag, and added the ammonia every day as he suggested (differed from the Dr. Tim method), and there was some tannins in the water when finished, which I got rid of overnight with a bag of purigen in my canister.

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On 1/12/2023 at 10:53 AM, Aiden Carter said:

Wait, your school system has an aquarium science class?!?!! I want one: (

No kidding. If my high school had classes like this and fermentation/brewing (for Dad, of course...) I might have actually been interested in science as a kid.

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So when designing experiments for ecology, which this effectively is bacterial ecology, you will never be able to isolate all the variables.

 

And doing so as @MattyM stated means that the population is not ready for increased bioloads and will fail. For instance you say some kids use driftwood and others use different decorations. Well as the driftwood decomposes it too releases building blocks for which bacteria feed. And here is where I say be VERY careful of aquarium science. He likes to input opinion stated as fact. He states in an article wood does not release nitrogen as it decomposes, it’s just cellulose. If that were true, wood would (lol see what I did there) not decompose and be a vital part of soil and aquatic ecology. Wood as it decomposes releases nitrogen phosphorus and a few other “building block” chemicals. It’s so necessary in some soils, plants will literally unalive themselves if mature wood isn’t present in the soil. I’m looking at you huckleberry bushes.

 

Anyway I digress before I write a novel. Ecology has too many variables to isolate and adding macro biology to the micro only complicates it further. So don’t. It is written in many early ecology books that trying to isolate a variable in an ecological system is doomed to fail. I would instead focus on the much more interesting cycle and how it relates to animal health. It is a far more interesting topic anyway and learning ecology in the current climate of the world Id argue is one of the most significant things a child can learn in the classroom. I really appreciate what you’re doing here and would have loved to take this class.

 

I will leave it at that, and invite some others here with science background to weigh in. @OnlyGenusCaps @dasaltemelosguy @modified lung @Odd Duck 

 

the aforementioned article from aquariumscience:

https://aquariumscience.org/index.php/14-10-wood/
 

and an article I skimmed about wood ecology on terrestrial organisms but I needed something because I felt what aquariumscience was saying was wholly untrue, but needed proof to ease my mind:

https://www.nature.com/articles/s41598-022-20377-3

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On 1/12/2023 at 10:29 AM, Biotope Biologist said:

And here is where I say be VERY careful of aquarium science. He likes to input opinion stated as fact. 

On 1/12/2023 at 10:29 AM, Biotope Biologist said:

I will leave it at that, and invite some others here with science background to weigh in. @OnlyGenusCaps @dasaltemelosguy @modified lung @Odd Duck 

the aforementioned article from aquariumscience:

https://aquariumscience.org/index.php/14-10-wood/
and an article I skimmed about wood ecology on terrestrial organisms but I needed something because I felt what aquariumscience was saying was wholly untrue, but needed proof to ease my mind:

https://www.nature.com/articles/s41598-022-20377-3

@Biotope Biologist, thank you so much for expressing this in such a constructive manner as I have exactly the same sentiments, but words failed me. Admittedly, I'm no fan of aquariumscience's absolutism or sensationalist style, but that alone would not exclude him as an information source. What does exclude him as such IMO is so much on the site is simply incorrect. I too would STRONGLY recommend that ANY information gotten from that site be VERIFIED.

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Some fish and critters do not do well in newer environments. Frogs I believe are one. Gearing towards hardier fish is a better idea. Things like zebra danios do well in newer tanks. 
So much life happens that is interconnected in longer running tanks we are usually unaware of become so vital to more sensitive tank inhabitants along with stability. Many critters just can’t handle the fluctuations occurring in newer setups. 
Also check that your students are selecting critters who do well in your water parameters and temps etc. 

Best of luck. 

Edited by Guppysnail
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On 1/12/2023 at 12:29 PM, Biotope Biologist said:

For instance you say some kids use driftwood and others use different decorations. Well as the driftwood decomposes it too releases building blocks for which bacteria feed.

This is an excellent observation!  Further, if the wood is decreasing the pH, that can slow a cycle as well.  Also, if the wood is added later, and the pH shifts, you can shift the community and temporarily destabilize it. 

Actually, I have a few suspicions about fishless cycles.  I've done them a number of times at this point, and I find them to be inherently less robust.  I suspect that my adding ammonium chloride we are only feeding the nitrifying bacteria, and not the critical heterotrophs which are responsible for consuming a variety of other organic waste compounds.  Without a reasonable population of these other decomposition organisms, once living, waste producing, interesting macro-organisms are added, the bacterial community still takes time to adjust.  I've not put a lot of thought into precisely how I see that playing out in the bacterial community as it relates the the ecosystem processes in the tank.  But, my observations seem to support the pattern even if the mechanism remains unknown.  This would also account for why putting in a well "cycled" sponge and instant cycle a tank as the entirety of the bacterial community is present for full waste decomposition.  It also help explain why so many people struggle with fishless cycling.

Against the advice of Dr. Tim (who I have had a couple of heated, but professional, discussions with on this topic), when I fishless cycle now, I do it for longer and continue to add ammonia, as you did.  But I do so until 2 things happen: 1. a large quantity of NH4 can be broken down in hours, 2. there starts to be a "gunk" build up from the dead and now decaying nitrifying bacterial populations, which would give the generalized heterotrophs something to eat and build their populations.  Since moving to this route, I've found fishless cycling to be more reliable.

On 1/12/2023 at 1:01 PM, dasaltemelosguy said:

I too would STRONGLY recommend that ANY information gotten from that site be VERIFIED.

I would broaden that our to, well, the whole Internet!  🤣

On 1/12/2023 at 1:08 PM, Guppysnail said:

Some fish and critters do not do well in newer environments. Frogs I believe are one.

Totally agreed!  As someone who would self identify as an "amphibian guy", I think you are spot on!  Amphibians are generally speaking a bad choice for unstable, and especially chemically unstable environments.  I know even back in the day, when my amphibian peeps set up a tank, we never considered it "ready" until it has been building up gunk for 3 months, at least!  When I was breeding alpine newts, they did better if the "new" tank was 6mo old or more.  Plus many amphibians don't really like hard water - which I think OP said he has - though I don't know this for sure with ADF. 

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On 1/12/2023 at 8:09 AM, GoGreen said:

The kids who cycle early, put in about .25 ppm of ammonia every testing day to ensure the bacteria stay alive.  

This may be one of the reasons. More importantly, what you seem to have here is another great lesson for your class.

The amount of ammonia in the water is the biggest factor  that determines which specific types of nitrifiers grow. The nitrifiers that started growing when the 4 ppm of ammonia was added may not be able to metabolize the 0.25 ppm ammonia. So the nitrifiers that prefer higher ammonia will entered dormancy during a lower ammonia period if it lasts too long because they can't eat any of it.

Meanwhile, the nitrifiers that prefer lower ammonia are very slow at metabolizing. They can be slow because they don't have to compete with the nitrifiers that prefer higher ammonia. If there isn't enough of the nitrifiers that prefer lower ammonia (because the cycle was complete only recently, that is the "biofilm" is still young), a single frog or fish can produce ammonia faster than the those nitrifiers can eat it.

But then the nitrifiers that prefer higher ammonia wake up and go into overdrive which creates a lot of nitrite very quickly. But in nature nitrifiers aren't used to being exposed to very much nitrite at a time. Any nitrite is usually there and gone almost immediately so most aren't adapted to nitrite exposure. That means if the nitrite gets too high, most if not all the nitrifiers will be affected. Some will slow way down, others may go into dormancy. Now even the still active nitrifiers that prefer higher ammonia can't metabolize it fast enough. 

What this will look like if you tested every day or maybe few hours is ...ammonia will go way up, then way down, nitrite will go way up, then ammonia will go up again but this time not as much, and nitrite will keep going up.

But if you do a big water change and get nitrite down below 0.9 ppm (in my personal experience), the next day the cycle will re-establish and work fine from there.

That's all an idealization of course. Weird things happen sometimes. It's impossible to know all the variables at play.

 

@Biotope Biologist @dasaltemelosguy lol warms my heart to see others jump in on being critical of aquariumscience.org. I seemed to be the lone voice in that corridor for a long time. 

Speaking of the bottled bacteria experiment on that website. Not saying he's necessarily wrong in his conclusion or that he did this on purpose, but he basically set up his bottled bacteria experiments to fail.

Edited by modified lung
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On 1/12/2023 at 8:09 AM, GoGreen said:

All of this prep work aside, both quarters when we have ordered fish and put them in the tanks, we end up with detectable levels of ammonia and nitrite in the tank, and some dead fish.

Could it be that the dead fishes are the cause of the measured ammonia spikes, at least in some cases? Even in established aquariums an undiscovered dead fish, hiding under a rock or behind a plant, is a plausible cause for a newly discovered ammonia spike.

In some of the Aquarium Co-Op videos Cory talks about what fish go through before they get to us. In a class on aquarium science it might be interesting to cover these aspects of the industry/hobby. After hearing some of the details I am amazed they survive as well as they do. Videos about Otocinclus (often wild caught and ill fed for many weeks) or "Neon Tetra Disease" (where he describes how mass produced tetras are raised) come to mind. It might prepare the students for the eventual, and essentially inevitable, eventually that death will occur in their tanks.

On 1/12/2023 at 1:21 PM, OnlyGenusCaps said:

Against the advice of Dr. Tim (who I have had a couple of heated, but professional, discussions with on this topic), when I fishless cycle now, I do it for longer and continue to add ammonia, as you did.  But I do so until 2 things happen: 1. a large quantity of NH4 can be broken down in hours, 2. there starts to be a "gunk" build up from the dead and now decaying nitrifying bacterial populations, which would give the generalized heterotrophs something to eat and build their populations.  Since moving to this route, I've found fishless cycling to be more reliable.

I once put a group of 12 Rummy-nose tetras into a new 45G "cycled" aquarium. It was using a canister filter from an established tank. Two died within a day for no obvious reason. The remaining tetras weren't showing consistent bright red noses for a good month or two, and then went on to live apparently happy lives for many years. There is definitely more than just the nitrogen cycle that impacts the health of fish in the aquarium.

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On 1/12/2023 at 10:29 AM, Biotope Biologist said:

He states in an article wood does not release nitrogen as it decomposes, it’s just cellulose. If that were true, wood would (lol see what I did there) not decompose and be a vital part of soil and aquatic ecology.

His argument isn't that it doesn't release any. It's that it wouldn't cause an ammonia spike. He mentions down lower that it does contain ~0.03% Nitrogen but that's consumed by the organisms breaking down the wood along with nitrogen compounds in the water (like how you need way more N vs C when composting)

https://www.routledgehandbooks.com/doi/10.1201/b12487-5#:~:text=Overall%2C dry wood has an,and trace amounts of inorganics.

On 1/12/2023 at 11:01 AM, dasaltemelosguy said:

@Biotope Biologist, I too would STRONGLY recommend that ANY information gotten from that site be VERIFIED.

Do you have any suggestions for good websites with more indepth info (besides ACO obviously)?

There's so much regurgitated "facts" online like a big game of telephone with no real citations or backing.. Like if you look up information about wood in aquariums, 75% of them recommend doing a fingernail test to see if it's hardwood to know that it's safe to put in your tank.

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I'm jumping in here late, but the kid with the guppies he/she brought in from home that did well likely also moved some beneficial bacteria on/in the fish and in the water he/she transported them in. Those extra bacteria may have been enough to help things along. Bacteria being fed chemical ammonia might not be as efficient as bacteria used to eating the more organic ammonia produced by live stock when confronted with organic ammonia. Ammonia is ammonia, but maybe not to the bacteria. Their guts full of food that you thought would trigger a spike, might have been also loaded with beneficial bacteria that the food deprived mail order fish were lacking.

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On 1/12/2023 at 2:31 PM, Schuyler said:

His argument isn't that it doesn't release any. It's that it wouldn't cause an ammonia spike. He mentions down lower that it does contain ~0.03% Nitrogen but that's consumed by the organisms breaking down the wood along with nitrogen compounds in the water (like how you need way more N vs C when composting)

https://www.routledgehandbooks.com/doi/10.1201/b12487-5#:~:text=Overall%2C dry wood has an,and trace amounts of inorganics.

All that is only half true. "Half true" is kind of the hallmark of that website which is what makes it both so believable and hard to debunk.

The initial N content of the wood doesn't really matter. The fungi and bacteria that break the wood down by accumulating and injecting N from the environment into the wood. Much of that N comes from nitrate which can at some point be turned into ammonia by other microorganisms as the wood breaks down. There's also evidence that some of the same fungi and bacteria that break down wood can directly reduce the nitrate to nitrite and ammonia themselves.

"Wood chip bioreactors" actually use wood to "soak up" nitrate to improve water quality. The wood chips are then discarded before they break down or put in an anaerobic environment for denitrification afterward.

So to add to what @Biotope Biologist said, without this N being injected by the fungi and bacteria, the wood wouldn't decompose. As the wood decomposes, much of the N is re-released as ammonia.

On 1/12/2023 at 2:31 PM, Schuyler said:

Do you have any suggestions for good websites with more indepth info (besides ACO obviously)?

Honestly, the ACO blog is probably the best source I've seen. 

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