Tanks without fish

BarryH

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I recently set up a 60cm tank with Redmoor Root and different mosses. The tank previously had a fancy goldfish in it but that's been moved to one of the larger tanks leaving it free. What I'm not sure of, and as I want to leave adding the fish (Cardinals) until after Christmas, will I be OK just leaving the tank running and doing my normal weekly cleaning?

With there being no fish in there, will the "bugs" in the filters still have something to chew on or should I be adding something?
 

dw1305

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Hi all,
will I be OK just leaving the tank running and doing my normal weekly cleaning?

With there being no fish in there, will the "bugs" in the filters still have something to chew on or should I be adding something?
Just leave it running, and feed the plants normally.

As long as you have a reasonable plant mass in active growth your tank is ready for the fish. The take "home message" is that low ammonia loadings create a diverse microbial fauna, which can respond to changes in ammonia level, and that plant/microbe biofiltration is about an order of magnitude more effective than "microbe only" biofiltration.

If you feel happier adding the occasional pinch of fish food to the tank it won't do any harm. While I didn't have any fish I've used <"Miracle Gro" as my fertiliser>, which has urea (CO(NH2)2) as the nitrogen source, and plant growth has been very good.

Science bit
There isn't any requirement to add ammonia to keep the filter "cycled", and it may actually do more harm than good. The traditional view of cycling was that the , limited range of bacteria, responsible for ammonia oxidation required high ammonia loadings and alkaline conditions. This is true, but we now know that they aren't the nitrifying organisms found in aquarium filters, so it isn't very relevant.

There are a number of recent scientific papers specifically on the nitrifying organisms in aquarium filters, which suggest that their assemblage shows a fluid response to varying ammonia loadings, with a stable core of Archaea and an ever changing cast of nitrifying bacteria.

This is described in <"Freshwater Recirculating Aquaculture System Operations Drive Biofilter Bacterial Community Shifts around a Stable Nitrifying Consortium of Ammonia-Oxidizing Archaea and Comammox Nitrospira">, Bagchi et al (2014) <"Temporal and Spatial Stability of Ammonia-Oxidizing Archaea and Bacteria in Aquarium Biofilters">
& <"Kinetic analysis of a complete nitrifier reveals an oligotrophic lifestyle">.

The last study (published in the journal <"Nature">) found that high ammonia levels inhibit the growth of Nitrospira.
Here we isolate a pure culture of a comammox bacterium, Nitrospira inopinata, and show that it is adapted to slow growth in oligotrophic and dynamic habitats on the basis of a high affinity for ammonia, low maximum rate of ammonia oxidation, high growth yield compared to canonical nitrifiers, and genomic potential for alternative metabolisms
cheers Darrel
 

BarryH

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Thanks for all the help Darrel, really appreciated. It's reassuring to know I'm on the right track. When you mention Miracle Grow, is that the product with small round balls of fertilser?
 

dw1305

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Hi all,
When you mention Miracle Grow, is that the product with small round balls of fertilser?
No, it is a soluble bright blue crystal and gives you a blue solution.

There are details in the <"It's very green"> thread.

You have to be really careful with <"fertilisers with a urea or ammonia content">, plants love them, but ammonia (NH3) is toxic to fish at levels below 0.5 ppm.

Some mixes containing urea (and/<"or ammonia">) are sold as "aquarium fertilisers", but always as very dilute liquid mixes, where you are unlikely to get toxic levels of ammonia, unless you massively over-dose.

Urea is a bit safer than ammonia, mainly because it has to be catalyzed to ammonia by a plant, or micro-organism, with the <"urease enzyme">.
Redmoor Root and different mosses.
I'd still definitely add a floating plant. The Salvinia <"you already have"> would be perfect.

cheers Darrel
 
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BarryH

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Thanks again Darrel. I forgot to add the Salvinia Auriculata in my original post. It's in there and doing very well, great to see the short roots getting slightly longer.
 

jaypeecee

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The last study (published in the journal <"Nature">) found that high ammonia levels inhibit the growth of Nitrospira.
Hi @dw1305

Did the study in Nature quantify "high ammonia levels"? The strain of Nitrospira identified by Dr Timothy Hovanec as being the nitrite oxidizer in freshwater aquaria is N. moscoviensis. Is this the strain cited in the Nature paper?

JPC
 

alto

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Nitrospira identified by Dr Timothy Hovanec
I’ve not read any recent work he’s done, but back when, he suggested a maximum of 1ppm ammonia N when fishless cycling, and pH 6.5 - 7.5 range with some pH effects outside this range
 

dw1305

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Hi all,
..Did the study in Nature quantify "high ammonia levels"? The strain of Nitrospira identified by Dr Timothy Hovanec as being the nitrite oxidizer in freshwater aquaria is N. moscoviensis. Is this the strain cited in the Nature paper? JPC
The Nitrospira strain used was N. inopinata. This has been isolated from a wide range of natural environments including soil water, aquifers and wastewater treatment plants etc. I think N. muscovensis was isolated from sewage sludge.
........Uncultured comammox Nitrospira are highly abundant in biofilms from groundwater wells, drinking water treatment systems, and freshwater biofilters exposed to bulk concentrations of NH4 + from ~4 to 60 µM1,23–26. Furthermore, recent amoA qPCR data showed that comammox Nitrospira were the most abundant ammonia oxidizers in a groundwater well containing on average 2 µM ammonium and they represented 12 to 30% of all detected ammonia oxidizers in a rice paddy soil, a forest soil and an activated sludge sample,.....The recent discovery of complete ammonia oxidizers (comammox) in the NOB genus Nitrospira1,2, which alone convert ammonia to nitrate, raised questions about the ecological niches where comammox Nitrospira successfully compete with canonical nitrifiers. Here we isolated the first pure culture of a comammox bacterium, Nitrospira inopinata, and show that it is adapted to slow growth in oligotrophic and dynamic habitats based on a high affinity for ammonia, low maximum rate of ammonia oxidation, high growth yield compared to canonical nitrifiers, and genomic potential for alternative metabolisms. The nitrification kinetics of four AOA from soil and hot springs were determined for comparison. Their surprisingly poor substrate affinities and lower growth yields reveal that, in contrast to earlier assumptions, not all AOA are most competitive in strongly oligotrophic environments and that N. inopinata has the highest substrate affinity of all analyzed ammonia oxidizer isolates except the marine AOA Nitrosopumilus maritimus SCM13. These results suggest a role of comammox organisms for nitrification under oligotrophic and dynamic conditions.
but back when, he suggested a maximum of 1ppm ammonia N when fishless cycling, and pH 6.5 - 7.5 range with some pH effects outside this range
It is an enzyme kinetics paper on an axenic culture, so it isn't directly comparable to studies on aquarium filters, although the same processes will be occurring in the filter.

The study says:
The calculated mean maximum oxidation rate of total ammonium (Vmax) was 14.8 μmol N mg protein-1 h-1 (s.d. 1.2, n = 6) (Fig. 1a and Extended Data Fig. 4). Remarkably, N. inopinata reached Vmax at total ammonium concentrations as low as 5 μM
The RMM of NH4+ is 18. So 5 microMolar equates to ((18/1,000,000) x 5) = 90 ppm NH4. This is an experimentally defined maximal value, so a bit like saying the top speed of a car is 200 mph, it doesn't mean it is always going that fast.

It also talks about maximal rate (Kmax) and that is about 1 microM, so 18ppm NH4.

I can email the pdf of the paper if you PM me.

cheers Darrel
 
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MJQMJQ

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Hi all, No, it is a soluble bright blue crystal and gives you a blue solution.

There are details in the <"It's very green"> thread.

You have to be really careful with <"fertilisers with a urea or ammonia content">, plants love them, but ammonia (NH3) is toxic to fish at levels below 0.5 ppm.

Some mixes containing urea (and/<"or ammonia">) are sold as "aquarium fertilisers", but always as very dilute liquid mixes, where you are unlikely to get toxic levels of ammonia, unless you massively over-dose.

Urea is a bit safer than ammonia, mainly because it has to be catalyzed to ammonia by a plant, or micro-organism, with the <"urease enzyme">.I'd still definitely add a floating plant. The Salvinia <"you already have"> would be perfect.

cheers Darrel
Sounds like hydrated copper sulfate.U mean above 0.5ppm?
Also remember its just one strain of bacteria being tested.In an aquarium there are many different types of bacteria.
 

dw1305

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Hi all,
U mean above 0.5ppm?
I mean at levels below 0.5 ppm, when you get to 0.5ppm, or above, then you will have killed most organisms.
Sounds like hydrated copper sulfate.
Arghhhhhhhhh. The blue pentahydrate form copper sulphate is included in the mix, but it <"most definitely"> isn't what dyes the fertiliser blue .
I found out the bright blue colour in Miracle Grow is Copper Sulphate. ;)
You know that pretty soon this will be all over the WWW, but minus the emoticon.

Before long it will be a "fact" and both our names will be forever associated with it. Who knows in the future wars may be fought between the true "blue believers" and their non-believing foe.

Fact: The pentahydrate of copper sulphate (CuSO4.5H2O) is blue and "Miracle-Gro® Water Soluble All Purpose Plant Food" contains copper sulphate. However I'm pretty sure (certain actually) that the 0.07% Cu content would be enough to give the fertiliser that bright blue colour.
cheers Darrel
 

jaypeecee

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I’ve not read any recent work he’s done, but back when, he suggested a maximum of 1ppm ammonia N when fishless cycling, and pH 6.5 - 7.5 range with some pH effects outside this range
Hi @alto

A starting ammonia level of 1ppm is a low figure but I've successfully started cycling at lower figures. Nowadays, I normally start a cycle at 3ppm ammonia but no higher. As for the pH range, the figures that you quote above are also low. I ensure that pH is from 7.4 to 8.0. Nitrifying bacteria seem to prefer alkaline conditions from what I've read.

Having said this, I'm not sure what point you were making.

JPC
 

dw1305

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Hi all,
Nitrifying bacteria seem to prefer alkaline conditions from what I've read.
An alkaline pH is probably not that relevant to the nitrifying microorganisms that actually occur in aquarium filters.

Basically since people were able to look for genes the range of organisms involved in nitrification, and the metabolic pathways utilised, have increased exponentially. I'd recommend the Bagchi et al. (2014) paper <"Temporal and Spatial Stability of Ammonia-Oxidizing Archaea and Bacteria in Aquarium Biofilters"> to every-one, it is both open source and a relatively accessible read.

I've got a lot of new scientific papers that I've just skimmed through, but it looks like the complete nitrifier (COMAMMOX) Nitrospira is much more ubiquitous and important in nitrification than had been realised.

I think these should be available to everybody Fowler et al. (2017) <"Comammox Nitrospira are abundant ammonia oxidizers in diverse groundwater‐fed rapid sand filter communities"> & Koch et al (2019) <"Complete nitrification: insights into the ecophysiology of comammox Nitrospira">. This is the abstract to the "insights" paper
Nitrification, the oxidation of ammonia via nitrite to nitrate, has been considered to be a stepwise process mediated by two distinct functional groups of microorganisms. The identification of complete nitrifying Nitrospira challenged not only the paradigm of labor division in nitrification, it also raises fundamental questions regarding the environmental distribution, diversity, and ecological significance of complete nitrifiers compared to canonical nitrifying microorganisms. Recent genomic and physiological surveys identified factors controlling their ecology and niche specialization, which thus potentially regulate abundances and population dynamics of the different nitrifying guilds. This review summarizes the recently obtained insights into metabolic differences of the known nitrifiers and discusses these in light of potential functional adaptation and niche differentiation between canonical and complete nitrifiers.
cheers Darrel
 
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