When Is A Cycle Finished?

[backtotropical]

I'm hoping to have space for 10 at a time (the tanks wont be huge anyway), but we'll have to see

That is an experiment in itself. Do larger tanks cycle faster or slower? To me, it would seem to make sense that a smaller tank would cycle faster. For argument sake, say it takes 1 million bacteria to process 1 ml of ammonia in 12 hours. In a 5 gallon tank that is roughly 5 ppm. In a 50 gallon tank though, 5 ppm would be 10 ml so it would take 10 million bacteria to process it. Thus meaning that the bacteria colony would have to double 3 more times (roughly 3 more days) from 1 million to get to over 10 million. But it would seem that most people say that smaller tanks take longer.

Interesting, RDD. I remember Bignose pointing out that the vast majority of the original bacteria which we multiply over and over again until we have a 'cycled' filter, actually comes from the tap water.

Surely then it would be the case that if say 5 gallons of water contained 1 million bacteria, then 50 gallons of water would most likely contain 10 million bacteria, effectively making the respective tanks cycle in the same time, assuming they are both subject to the same ammonia concentration?

The only other factor which i can think may play a part in this is the flow of the filter (ie. how quickly the bacteria establish their breeding ground in the filter media), but as a 50g should in theory have 10 x the filtration capacity of a 5g (and therefore 10x the flow rate), again all should be equal. Of course, i have no evidence to back that up (seems to be quite common on this topic) but it may be an idea to experiment with flow rates too? Say have 2 identical tanks with identical filter media but 1 filter turning over say 300l/h and the other turning over 1500l/h, and monitor whether it has any effect on cycling time?

I suspect (although again no evidence) that small tanks take longer to cycle for the same reason that small tanks are more volatile in respect of water parameters. The less water, the quicker things can build up / go wrong etc etc.

As we all know there are many contaminent factors in our water which we can't / don't measure because it just isn't practical, and small tanks would be more susceptible to these (purely due to the small volume of water), should any of these contaminents be prone to stalling our cycle. This may also contribute to Bignose's theory that water changes during the cycle are beneficial, as it may be the case that water changes are removing these pollutants, hence allowing the cycle to progress faster.

I agree we definitely need some experiments carried out here, but its a case of finding someone with the cash, the space and the time. Ian??

BTT

 

[rdd1952]

What you say makes sense on the bacteria per gallon. I guess I never really thought it through. I have always thought that the small ones took longer and I'm sure it's as you say, just the volume of water. Drops in pH are much easier in a small amount of water.

If you had the time, money ans space, there is almost an infinite number of things you could test to see how they affected cycling. I wonder if we could get a grant from the government??? I have heard of them giving grants for much dumber things that this.

 

[iankent]

What you say makes sense on the bacteria per gallon. I guess I never really thought it through. I have always thought that the small ones took longer and I'm sure it's as you say, just the volume of water. Drops in pH are much easier in a small amount of water.

If you had the time, money ans space, there is almost an infinite number of things you could test to see how they affected cycling. I wonder if we could get a grant from the government??? I have heard of them giving grants for much dumber things that this.

EU or UK national lottery funding might be an option, though it might mean establishing a charity first (not all that difficult), plus dedicated people with lots of spare time

BTT - i'll see what I can do

haven't had a chance to do much this weekend, and using my Q tank as a control didn't go too well - decided it's going to be my permanent frog tank (so still need to get a Q tank lol), then accidentally contaminated it with water from the main tank, and didn't feel like cleaning it all out and starting again! doubt much will happen during the week either, but next weekend

anyone got any suggestions for the first thing(s) to compare? for worthwhile results we should change only one variable in each set (could either do a set of 10 or two sets of 5 if i have space), so what do you think first? frequency of water change could be a good start?

 

[Miss Wiggle]

If you're going to do a series of experiments then you need to run a control alongisde each one with the same original water in it.

For me the most interesting thing is pH, if I was gonna start out I'd do one at a high pH, one at a low pH and have your control running at neutral or there abouts.

Up to you what you start with though!

 

[waterdrop]

If you're going to do a series of experiments then you need to run a control alongisde each one with the same original water in it.

For me the most interesting thing is pH, if I was gonna start out I'd do one at a high pH, one at a low pH and have your control running at neutral or there abouts.

Up to you what you start with though!

Totally agree with this because this is one of the areas where the advice could be a bit better handled by beginning fishless cyclers. I was quite interested to see in one of Tim Hovanec's published articles that he was controlling water at 8.0 pH in his line of test tanks. My thought has been that perhaps something as simple as having people bring pH up to 8 via baking soda(more controllable but more maintenance work) or crushed corel (less controllable) might avoid some slower cycle processes for those who start out with lower pH.

I recognize that this would be easier at the start and get harder as nitrates begin to push the pH down and other factors make swings happen perhaps.

~~waterdrop~~

 

[iankent]

Decided to do a bit of research into pH etc, to see what we were up against, and found out quite a bit of interesting info! Sorry if this isn’t as well written as it could be, but I wrote it all out then Firefox crashed, so now I’m writing it all out again (in Word...)!!

(Just looked back through, and didn’t realise it was so long – sorry )

Converting Ammonia to Nitrite
When we convert 1mg Ammonia into Nitrite, our bacteria:
• Use 1.878905mg Oxygen
• Produce 2.701352mg Nitrite
• Produce 0.177553mg Hydrons (hydrogen ions)

The bacteria
I couldn’t find too much info on aquarium bacteria, but did manage to find a few interesting pages. There’s a good quote in this article (http/www.springerlink.com/content/m8np468735540x17/fulltext.pdf - page 20):

‘isolated a Nitrosomonas species from a Louisiana freshwater marsh and found that optimum growth in culture occurred at pH 8.5, 35 C, and ammonium concentrations greater than 0.5 g/l.’

This seems to go against the usual advice of a near neutral pH and temps of no more than about 30. The 500ppm ammonia is also much higher than we use – we normally avoid this to stop getting the wrong type of bacteria, but that didn’t seem to be a problem for Nitrosomonas.

That article also mentions on the same page that this particular bacteria need Phosphorous to grow, which is something a brand new tank could lack (or lack in any worthwhile quantities) – haven’t checked my local water stats at all, but would assume it’s quite low in phosphorous?

I’m going to try and grow my filter bacteria to try and identify it – will let you know!

Another article I found, also mentioning Nitrosomonas (http/www.freepatentsonline.com/5314542.html) mentions that they are killed by their own waste (Hydrogen ions) – see the bit below on Hydrons!

One of the two articles (cant remember which sorry) says that these are also just slow multiplying bacteria, and can take a few days to multiply in numbers – e.g., it might not be the double in 24 hours we’ve been working from?

Converting Nitrite to Nitrate
If we take 1mg of the nitrite produced, and let our bacteria process it, they’ll:
• Use 0.391589mg Water
• Produce 1.347771mg Nitrate
• Produce 0.043818mg Hydrons

The bacteria
Haven’t had a chance to do any research on these, but will find out more soon – hopefully! I’d imagine they’d be happy in more or less the same conditions as the ammonia oxidising bacteria!

The Hydrons
I’d always just assumed that the Hydrons (hydrogen ions) would dissipate at the surface of the water, but I was completely wrong! When the Hydrons are released into the water, one of two things could happen:
• It’ll react with NH3 (Ammonia) to become NH4+ (Ammonium)
• It’ll react with H2O (Water) to become H3O+ (Hydronium)

Ammonium isn’t so much of a problem, but if we’re producing Hydronium then that could be.

Hydronium
Hydronium is the most acidic chemical known to exist in water (http/en.wikipedia.org/wiki/Hydronium), with a pH of -1.7. It’s formed when hydrogen ions are mixed with water, forming H3O+.

Apart from its pH, it’s also highly toxic to the bacteria that produced it (and fish!). High levels of Hydronium will kill the bacteria we’re trying to grow, as well as potentially causing a pH crash.

For every 1mg of Hydrons, you end up with 7mg of Hydronium

Adding it all up
If we start out with 1mg ammonia, our bacteria will end up producing:
• 2.701352mg Nitrite
• 0.177553mg Hydrons, which forms 1.065318mg Hydronium

The 2.701352mg nitrite will then be processed into:
• 3.640803886392mg Nitrate
• 0.118367841936mg Hydrons, which forms 0.710207051616mg Hydronium

After our 1mg ammonia has been processed entirely, we’re left with:
• 3.640803886392mg Nitrate
• 1.775525051616mg Hydronium

That’s all in mg!
To give a better idea, here it is in ppm. If we add 5ppm ammonia to a tank, then wait for the ammonia to drop to 0, we’ll have readings of
• 18.20ppm Nitrate
• 3.55ppm Hydronium

I was hoping to calculate the number of hydrogen ions needed to make up 3.55ppm Hydronium in a 100L aquarium, which would allow us to calculate the pH crash that would be expected (if it’s even noticeable), but haven’t had time!

in summary, just based on the Hydronium issue (which as far as I know, we can’t test for), my opinion would be that we should encourage people to do regular water changes while fishless cycling to:
• reset the pH to tap water levels
• provide fresh oxygen to the bacteria
• clear any nitrite backlog that’s built up
• remove Hydronium which may kill our bacteria

doing a complete water change just before raising the ammonia levels back up would be a good time - we know that it wont have any negative impact on the tank (as long as the water's dechlorinated!), it just means a little bit more effort to possibly save some time!

hopefully all that made sense – as I said, had to retype the entire thing lol... and sorry for the lack of references in some places, I only started keeping references about half way through!

Would certainly make experimenting with pH interesting, and very difficult! I’m not too sure where we should start with this one – finding out what effect Hydronium has on pH would be a good start I suppose, because if it is Hydronium to blame then regular water changes are a must!

How about a set of tests with varying water changes - e.g. cycle a tank with no changes right up to a tank with daily changes?

p.s. I might have gone a bit OTT with the decimal places, especially considering how inaccurately we’d measure 1mg of ammonia anyway...

Any comments?

Ian

 

[rdd1952]

Could you repeat that???

Based on what you have there, it would seem to partly explain the constantly dropping pH during a fishless cycle. The hydronium could be what is pushing it down rather than the high nitrates. I don't know if that is the case or not though as since it is toxic to the bacteria, you would think it would also wipe out any bacteria present.

I definitely think water changes are the way to go. The simple fact that 1 ppm of ammonia results in 2.7 ppm of nitrite certainly explains why the nitrite spike lasts o long. if you put in 4 ppm of ammonia every day for 2 weeks (the estimated amount of time we say the nitrite spike should run), you would end up with 151.2 ppm of ,less what is processed of course. And it's pretty certain that if there is enough bacteria to handle 4 ppm of ammonia in 12 hours and they are also able to process the resulting 10.8 ppm of nitrite in a 24 hour period, I think (obviously, no proof) the tank is definitely cycled.

I think the simplest way to answer that question for certain though is via adding the 4 ppm of ammonia via a drip or simply with a dropper over the course of the 12 hours to see if there is ever actually a nitrite reading. My theory is that there would not be as there should be enough bacteria present to process it as it's produced.

 

[iankent]

Based on what you have there, it would seem to partly explain the constantly dropping pH during a fishless cycle. The hydronium could be what is pushing it down rather than the high nitrates. I don't know if that is the case or not though as since it is toxic to the bacteria, you would think it would also wipe out any bacteria present.

I remember reading in one of the articles that the ammonia oxidising bacteria will protect themselves by whatever means they can, including piling up on top of each other into a gooey mess - its possible that the inner bacteria are protected long enough to survive until a water change, but would mean you actually appear less cycled after the water change than you did before....

edit: it's also a consideration for a fully stocked tank too - the nitrogen cycle there is also producing hydronium as well as nitrate, so you could call for more regular water changes in a cycled tank to clear that - it'd have to be based on calculated levels from the nitrates though, seeing as its unmeasurable

I think the simplest way to answer that question for certain though is via adding the 4 ppm of ammonia via a drip or simply with a dropper over the course of the 12 hours to see if there is ever actually a nitrite reading. My theory is that there would not be as there should be enough bacteria present to process it as it's produced.

well, my frog tank is nearly cycled (cheated with some filter media, it had all gone way off plan anyway lol), so once it's done I'll drip in some ammonia for a few hours and test the readings every half hour!

--

edited to add: something that might be worth trying is, after following the add and wait method, take a water sample and dilute and test until you get a reading - would be interesting to see how accurate the calculations are!

 

[Bignose]

ian, you have to be careful about reading too much into any one species of ammonia oxidizing bacteria (AOB) or nitrite oxidizing bacteria (NOB). For example, read this quote from Burrell, Phalen, and Hovanec "Identification of Bacteria Responsible for Ammonia Oxidation in Freshwater Aquaria" APPLIED AND ENVIRONMENTAL MICROBIOLOGY 2001

"When ammonia concentrations were varied, AOB population
shifts did occur, thereby altering the presence and activity
of important AOB. Low-ammonia environments will likely
produce Nitrosomonas marina-like AOB, while as the ammonia
concentration increases, Nitrosospira tenuis-like and Nitrosomonas
europaea-like AOB will become important until at the
highest ammonia concentration Nitrosococcus mobilis-like
AOB may be predominant. Our results suggest that the AOB
found in fish culture environments, such as public aquaria,
aquaculture facilities, and home aquaria, where the ambient
ammonia concentration rarely exceeds 5 mg of N per liter, are
different from the traditional Nitrosomonas europaea-Nitrosococcus
mobilis cluster type AOB, which are prevalent in the
high-ammonia concentrations typically found in environment
such as wastewater and sewage treatment facilities. This, and
our results with enrichments of the various strains of AOB in
newly set-up aquaria, strongly suggest that start-up inocula for
the establishment of nitrification in aquatic culture systems
should optimally consist of Nitrosomonas marina-like AOB
rather than Nitrosomonas europaea-Nitrosococcus mobilis cluster
AOB."

I think that it is very unclear what species is the primary AOB in home aquaria. It may very well be a mix of different AOBs, and will be dependent on local water supplies (the bacteria come in with the water a lot of the time). So, any information about any one specific species of bacteria probably isn't going to be particularly informative about any one tank.

 

[Miss Wiggle]

hmmm yesterday morning my boss makes me do complicated maths by hand to test if excel is working properly..... this morning i'm on a bleedin train at 6:48am and I decide to read this!! Think I need some more caffiene.

It's interesting about the hydronium though, I'd never even heard of that before today, could certainly go some way to contributing to the pH crash..... can we test for hydronium in any way?

 

[waterdrop]

Yes, reading the AEM articles quickly gives you an appreciation for how difficult any species identification is, even for a well-equiped university lab. I would deem it impossible for any home experiment.

~~waterdrop~~

 

[pastabake]

I don't think its necessarily important to know the species. Your bacterial culture consists of many more species than just the main AOB & NOB ones, it will be a complete eco-system. I also expect that there will be predator species in there too. The issue is more about keeping a balance.

You can test for hydronium its called a pH test.

The pH of a solution is a measure of its hydrogen ion concentration. Since free protons react with water to form hydronium, the acidity of an aqueous solution is determined by its hydronium concentration.

 

[iankent]

I don't think its necessarily important to know the species. Your bacterial culture consists of many more species than just the main AOB & NOB ones, it will be a complete eco-system. I also expect that there will be predator species in there too. The issue is more about keeping a balance.

You can test for hydronium its called a pH test.

The pH of a solution is a measure of its hydrogen ion concentration. Since free protons react with water to form hydronium, the acidity of an aqueous solution is determined by its hydronium concentration.

I think the biggest issue with the bacteria is that because of the many varying types and the range of conditions each can thrive under, we're never going to identify which is best. But in all honesty, from our perspective of trying to speed up a cycle do we really care what the bacteria is, or do we just care about what conditions it performs best under? As you say, comparing between two different AOB may be entirely pointless, but what it does demonstrate is that the same bacteria are happy to grow in a freshwater environment with (relatively) low ammonia levels, as well as very happily in extremely high ammonia levels.

Actually, a pH test is only testing for a balance between H+ and OH-, not for hydronium levels. We dont really need to know the balance of H+/OH- on anything more complex than the pH scale itself, but being able to calculate a pH crash based on a specific concentration of hydronium would be useful.

 

[waterdrop]

I don't think its necessarily important to know the species. Your bacterial culture consists of many more species than just the main AOB & NOB ones, it will be a complete eco-system. I also expect that there will be predator species in there too. The issue is more about keeping a balance.

You can test for hydronium its called a pH test.

The pH of a solution is a measure of its hydrogen ion concentration. Since free protons react with water to form hydronium, the acidity of an aqueous solution is determined by its hydronium concentration.

Oh, but its FUN Its just in our nature! Its just something that one does as Biology advances...

I agree its not terribly important that we know the exact name at a given moment. Heck, they're probably mutating fast enough to enter the "What is a species?" debate that probably continues all over the bio world.

For our purposes in the hobby (or in the world of fish farms or wastewater treatment for that matter, probably) its easy to get by with symbolic names (like A-bacs or AOBs or N-Bacs or NOBs) and the important things are the processes and so forth. But I do think that in the science, things will slowly advance and putting accurate identifications on what is going on is important and could eventually yield new insights.

An example of this is the reported situation where we see a different species of bacteria (among the eco-system, as you mention) being encouraged when our ammonia concentration gets up around the 8ppm amount. We know this slows our fishless cycle process, but is the nature of that slow-down very well characterized? I don't think we know much about it - we don't know if these other bacteria will die off slowly or suddenly once we lower the level back down below 8ppm or exactly what all that is like.

I mean one can't really have high expectations that much science will get done in our area of interest since it is hardly funded at all, but we do have the occasional bit from companies in field or from fish farming or other areas that use bacteria.

OK, I will stop yakking, lol, I just find it so interesting whenever we -do- manage to get any little glimpses from those articles in JAEM etc., don't you?

~~waterdrop~~

 

[Miss Wiggle]

For our purposes in the hobby (or in the world of fish farms or wastewater treatment for that matter, probably) its easy to get by with symbolic names (like A-bacs or AOBs or N-Bacs or NOBs) and the important things are the processes and so forth. But I do think that in the science, things will slowly advance and putting accurate identifications on what is going on is important and could eventually yield new insights.

I like calling them NOB's, it's the nitrite bacteria that are such awkward little buggers