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Consistency Deficiency
- Thread starter Hufsa
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_Maq_
Member
@Hufsa , thanks for nice photo-documentation. Now I rather believe it's a bacterial colony, quite possibly sulfate-reducing or sulfide-oxidizing.
Yet one more note: Sometimes when rearranging hardscape, you turn over a stone and its surface is black. But not the sand beneath the stone. From that I deduce that iron sulfide tends to adsorb to such surfaces, but perhaps not iron sulfide itself but bacteria which cause its creation.
As for cyanobacteria, I know from books that not all of them are actually blue-green; very different colours are possible. But don't ask me about details.
Yet one more note: Sometimes when rearranging hardscape, you turn over a stone and its surface is black. But not the sand beneath the stone. From that I deduce that iron sulfide tends to adsorb to such surfaces, but perhaps not iron sulfide itself but bacteria which cause its creation.
As for cyanobacteria, I know from books that not all of them are actually blue-green; very different colours are possible. But don't ask me about details.
Not necessarily, I think. Hydrogen sulfide gets quickly oxidized upon entering oxic layer of the substrate. Apart from that there are bacteria which oxidize H2S or HS-.
Hi @Hufsa
Correct. I don't know of any fish, shrimp or snails that eat Oscillatoria - and survive. It's quite something that you've managed to avoid 'BGA'. That tells its own story. I'd be interested in knowing more about your setup(s) in terms of water parameters, use of CO2, filtration, lighting, etc. Perhaps it's the Norwegian water?
JPC
That should rule out that then 🤔
Is it? I didnt think it was particularly remarkable to be honest, I thought every aquarist had one or two types of algae that they tend to struggle with, and some they never really see much of.
The ones ive had as my most "faithful companions" are BBA and some thread algae
I recently did a little write-up on my water values for Maq, you can find it here.
For the rest you may have to hunt a bit, although maybe it would be cruel of me to send people to read through all my ramblings hunting for useful info 😅
Maybe! Although it could just be a side-effect of the Cryptocoryne viagra
Hi @_Maq_
I don't know much about substrates. Is there a distinct oxic layer within the substrate? If there are plants rooted in the substrate, do these not oxidize zones within the substrate?
JPC
_Maq_
Member
Oxygen penetrates the substrate only millimeters deep, that's the oxic layer. Beneath is a suboxic layer where bacteria respire nitrate. Beneath that, anoxic layer follows.
Yes, plants oxidize the rhizosphere, but only 1 to 4 mm max around the roots. In that way they create a very important microcosm inhabited by many bacteria. Many essential microbial processes occur near the roots.
ElleDee
Member
What is the basis for the stated depth of "only millimeters"? Is that supposed to account for differences in substrate, the amount of flow present, and any bioturbation from fauna?
_Maq_
Member
Science. Scientific papers. Water does not flow in the substrate. Only dissolved substances diffuse.
Yes bioturbation, and other factors may influence it, but not in the orders; it's still millimeters.
[Citation needed] 😁
_Maq_
Member
Thanks for some more information @_Maq_ , could you share the part where they describe the physical properties of the sediments studied?
I believe many natural sediments will be more densely packed than our aquarium sediments, as ours usually are composed of an artificially narrow band of grain sizes. This leads to less compaction, which is why some of us, myself included, do not recommend play pit sand for aquarium use as it will compact quite a lot.
I also can't see anywhere in this study where they for example account for gravels or aquasoils with a grain size of 2-3 mm or more. Water circulation in that kind of substrate should be a fair bit more than in my very fine sand.
Basically, based on the sources you have shown me so far I do not think you have sufficient backing to go out as strongly as you have and declare things to always be "x" way.
I believe many natural sediments will be more densely packed than our aquarium sediments, as ours usually are composed of an artificially narrow band of grain sizes. This leads to less compaction, which is why some of us, myself included, do not recommend play pit sand for aquarium use as it will compact quite a lot.
I also can't see anywhere in this study where they for example account for gravels or aquasoils with a grain size of 2-3 mm or more. Water circulation in that kind of substrate should be a fair bit more than in my very fine sand.
Basically, based on the sources you have shown me so far I do not think you have sufficient backing to go out as strongly as you have and declare things to always be "x" way.
_Maq_
Member
Pardon me, I forgot to mention the source. It's not a study, it's a textbook: Fenchel, King, Blackburn - Bacterial Biogeochemistry. The Ecophysiology of Mineral Cycling [2012]. So, if the authors write that oxic zones range from less than 1 mm to 15 cm, it covers many various biotopes.
I do not function as a librarian. I'm sorry, I remember information but tend to forget where and when exactly I've got it. That's why my pronouncements on things which are solved to me are straight, while I'm in dire straits to point to the best sources in a minute. I know people are reluctant to admit that their substrate is not oxygenated. I can understand it very well, because I had those feelings myself. Only after reading many papers which over and over repeated the same, I accepted it as a fact. In eutrophic waters (all our tanks are eutrophic) the normal range of oxic zone counts in millimeters.
Do you want me to go through my library and present you with more resources? It would be rather hard job but I'm ready to pass this test of my sincerity.
I do not function as a librarian. I'm sorry, I remember information but tend to forget where and when exactly I've got it. That's why my pronouncements on things which are solved to me are straight, while I'm in dire straits to point to the best sources in a minute. I know people are reluctant to admit that their substrate is not oxygenated. I can understand it very well, because I had those feelings myself. Only after reading many papers which over and over repeated the same, I accepted it as a fact. In eutrophic waters (all our tanks are eutrophic) the normal range of oxic zone counts in millimeters.
Do you want me to go through my library and present you with more resources? It would be rather hard job but I'm ready to pass this test of my sincerity.
Is it accurate then for you to say that its "only millimeters"? No matter the substrate?
I understand not having every source memorized, but the burden of proof is on the person making the claim. If you say "x is always the case" then you should expect and be ready for people to question you on it
This isnt what my concern is, my concern is the sweeping statement you made that you made out to sound like it applies universally. Im not the only one who would like to discuss how many millimeters we think various substrates allow for regarding oxygenation.
Again you sweep every tank with all their differences under one. Your source says millimeters to 15 cm [Edit: 20 cm]. How did you determine that all of our substrates fall in the lower range?
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Hi @_Maq_
Dependent on the test method, parameters will range from unmeasurable to measurable. Actual figures would be preferable.
JPC
Hi @Hufsa
Yes, "something of that sort" may well be correct! The following resource may help with identification. Take a look at the Sulphur and Iron Oxidising Bacteria section.
Proteobacteria: The 16 Major Groups Examined | Earth Life
Proteobacteria is the second largest group of bacteria. This phylum contains 1,534 species - or 32.3% of all known bacteria.
earthlife.net
I was particularly interested to read that "Beggiatoa is a filamentous gliding bacterium which oxidises sulphur compounds in a similar way to Thiobaccillus. It is commonly found in sulphur springs, sewage works and hydrothermal vents. It can also be found in rotting piles of seaweed and in the rhizosphere of plant roots – in swamps where it lives at the boundary between the aerobic or oxic layer around the roots and the anoxic soil nearby".
JPC
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ElleDee
Member
I want to point out that the authors do not say the range of the oxic zone is less than 1 mm to 15 cm, they say it goes to 20 cm or more.
I found this paper that goes into some details about the different factors that influence that depth in sections 2.1 and 2.2. My read is that if oxygen flux into the soil is largely through molecular diffusion the oxic layer will be very shallow (though sediment porosity is still a factor here, as is noted in 2.2). However, in our aquariums we generally have a constant flow of oxygen rich water at the sediment level, light that penetrates to the substrate to support photosynthesis, and we may have significant bioturbation from livestock. We also regularly remove organic matter whose decomposition would deplete oxygen, and of course we may have a significant network of plant roots. All of these things work to increase the depth of the oxic layer in ways that are not present in a typical eutrophic lake.
I don't think any of this is in conflict with the source you posted, btw, this is a disagreement in interpretation.
Do I know how deep Hufsa's oxic layer is? I don't, and I don't particularly care. (I also don't care about the answer in my own tanks absent any particular problems, and obviously I wish Hufsa great success in all her endeavors.) But I don't think we have good evidence that it's extremely shallow in every tank, period.
John q
Member
I go to journals to see nice photos of planted tanks and cute fish 😎
I follow this journal closely because of all the cool plants and because Hufsa is growing Ludwigia Pantanal and Ammannia 'Golden' and I want to get as much info as possible how to grow both plants together 🌿🌱🌾
I follow this journal closely because of all the cool plants and because Hufsa is growing Ludwigia Pantanal and Ammannia 'Golden' and I want to get as much info as possible how to grow both plants together 🌿🌱🌾
_Maq_
Member
This one is good, though not exactly what I'm searching for, give me some time, please:
Influence of sediment organic enrichment and water alkalinity on growth of aquatic isoetid and elodeid plants
Influence of sediment organic enrichment and water alkalinity on growth of aquatic isoetid and elodeid plants
_Maq_
Member
It so happened that I've made some statements here in a careful fashion to which I've got a response that I preached to the converted. It seems that this is not the case, so pardon me for not anticipating that it would come as a novelty to you. I'm sorry.
Yes, oxygen can reach more than 10 cm into the sediments. It was occasionally observed in deep oceans where oxygen content was low, yet organics so sparse that the sediment oxygen demand (SOD) was near zero.
Bioturbation, porosity of the sediment, flow of the water etc. etc. have only secondary, limited effect on oxygen penetration. SOD is decisive.
In shallow highly productive and densely planted waters the SOD is highest. ALL our tanks are eutrophic by OECD standards, and SOD is high. So, oxygen penetration counts in millimeters.
I'll keep on searching my library for more papers on this topic, and post them here.
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