# Tanks without fish



## BarryH (4 Dec 2019)

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?


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## dw1305 (4 Dec 2019)

Hi all, 





BarryH said:


> 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


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## BarryH (4 Dec 2019)

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?


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## dw1305 (4 Dec 2019)

Hi all, 





BarryH said:


> 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">.





BarryH said:


> 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 (4 Dec 2019)

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.


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## jaypeecee (4 Dec 2019)

dw1305 said:


> 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


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## alto (5 Dec 2019)

jaypeecee said:


> 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


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## dw1305 (5 Dec 2019)

Hi all, 





jaypeecee said:


> ..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.
		
Click to expand...




alto said:



			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
		
Click to expand...

_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
		
Click to expand...

 _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 (5 Dec 2019)

dw1305 said:


> 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.
> 
> ...


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.


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## dw1305 (5 Dec 2019)

Hi all,





MJQMJQ said:


> 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. 





MJQMJQ said:


> 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 . 





Aqua sobriquet said:


> I found out the bright blue colour in Miracle Grow is Copper Sulphate.





dw1305 said:


> 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


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## jaypeecee (5 Dec 2019)

alto said:


> 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


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## dw1305 (5 Dec 2019)

Hi all,





jaypeecee said:


> 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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