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This is a discussion on study & questions within the Advanced Freshwater Discussion forums, part of the Freshwater Fish and Aquariums category; --> Acidifying of the substrate is going to be a relative process I believe. In a lake the bedrock is an input of buffers as ...

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Old 03-30-2014, 04:46 PM   #21
 
Acidifying of the substrate is going to be a relative process I believe. In a lake the bedrock is an input of buffers as well as runnoff and groundwater. The substrate is only going to acidify if the buffers allow it to and that depends on acid production and the input of buffers. If it is biological activity that is causing the acidification then no there does not need to be a proportional amount of basic molecules produced in the system. Its typically the addition of hydrogen that increases acidity, this is reduction and more prone to an anoxic environment.

Digestive system is aerobic and anaerobic.

The food chain doesn't really consume nutrients. Some become the makeup of of the fish while others are broken back down from complex molecule to basic nutrient then excreted for energy production. Every event of consumption, plant to fish, fish to fish, fish to bigger fish, ect. There is high energy loss each time. Much of what is consumed goes towards biological functions and is broken down then expelled as waste. Chapter 19 covers this in detail.

Bob thats guessing again. No circulation simply means diffusion between air and water is what will depend on O2 and CO2 conc. If the aquatic environment is consuming both faster then diffusion then they will be lower then equilibrium. If it is producing them at a faster rate they may be slightly higher. If the tank is overall not very productive they will likely be at equilibrium. But again its all just speculation unless you bother to test them. I have tanks with plants and usually no circulation as well, and nothing all to amazing about them. Currently my soil, planted uncirculated tank has significantly lower pH then my soil planted circulated/filtered tank, by almost a full degree using the same tap and similar water changes. But that doesn't really say a whole lot, there are many ways to effect the pH.
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Old 03-31-2014, 07:40 AM   #22
 
Mikaila, ...

i didn't even consider food being consumed just for it's energy value/content, so obvious now.

thanks for the heads up :)
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Old 03-31-2014, 08:33 AM   #23
 
page 249 - nitrogen

maybe i'm slow or something, ...

i look at this and can't help but think "the energy is backwards", ...

to me, it looks like ammonium has the lowest energy, and nitrate has the highest
this is backwards to my familiarity with bacteria & whatnot looking at the nitrogen cycle trying to obtain energy from ammonia, and releasing nitrite, and obtaining energy from nitrite and releasing nitrate.

i'm sure it's some mental stumbling block but i look at this and can't wrap my head around it, it just seems backwards

my head says Ammonia/ammonium should have the highest energy

am i just daft here and missing the obvious or is there something going on i'm just not getting ? :(


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Old 03-31-2014, 09:09 AM   #24
 
Quote:
Originally Posted by Mikaila31 View Post

...

Bob thats guessing again. No circulation simply means diffusion between air and water is what will depend on O2 and CO2 conc. If the aquatic environment is consuming both faster then diffusion then they will be lower then equilibrium. If it is producing them at a faster rate they may be slightly higher. If the tank is overall not very productive they will likely be at equilibrium. But again its all just speculation unless you bother to test them. I have tanks with plants and usually no circulation as well, and nothing all to amazing about them. Currently my soil, planted uncirculated tank has significantly lower pH then my soil planted circulated/filtered tank, by almost a full degree using the same tap and similar water changes. But that doesn't really say a whole lot, there are many ways to effect the pH.

Perhaps it is the combination of no water changes and lack of circulation.
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Old 04-01-2014, 08:43 PM   #25
 
Quote:
Originally Posted by Flear View Post
maybe i'm slow or something, ...

i look at this and can't help but think "the energy is backwards", ...

to me, it looks like ammonium has the lowest energy, and nitrate has the highest
this is backwards to my familiarity with bacteria & whatnot looking at the nitrogen cycle trying to obtain energy from ammonia, and releasing nitrite, and obtaining energy from nitrite and releasing nitrate.

i'm sure it's some mental stumbling block but i look at this and can't wrap my head around it, it just seems backwards

my head says Ammonia/ammonium should have the highest energy

am i just daft here and missing the obvious or is there something going on i'm just not getting ? :(


Attachment 326193
What you are missing is that figure shows nitrogen assimilation. Basically plants (macrophytes) and other photosynthetic organisms can only uptake ammonia/ammonium, I recall we discussed this in another thread. They do use nitrate and nitrite but as mentioned they have to convert it back to NH3/NH4. Ammonia does have higher energy so they are working against the energy flow and the plants do have to put in energy to make this conversion. The diagram shows the enzymes required to make these reactions and the number of electrons used to get nitrate and nitrite to a usable form. This is the reason plants prefer NH3/NH4. They will only use nitrate and nitrite if they need to as they can not gain as much energy in comparison to ammonia. The only exception to this is nitrogen fixation which is also depicted there along with its very high energy requirements.
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Old 04-01-2014, 10:07 PM   #26
 
redox isn't necessarily equal to potential energy content ?

i think that's the part i was missing

Edit:
i'm familiar enough with plants preferring Ammonium over nitrate, although they can take in both, ... and ammonium is preferred as the plants have to work extra hard to convert nitrate backwards till it reaches ammonium

i've also stumbled across the internal pH of plants ensures the presence of ammonium (over ammonia) so plants have ammonium to use at their disposal.

Last edited by Flear; 04-01-2014 at 10:11 PM..
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Old 04-04-2014, 03:17 PM   #27
 
Iron - Redox vs pH

Iron is really screwing with me. (not counting chelates)

i'm left to guess that Ferric iron is oxidized, ... but i'm not sure.
-if oxidized it would make sense to me to list it as Fe2O3
instead what i am seeing mention of is Fe3+

in the presence of O2 it's supposed to turn into ferric iron, ... k
ferric iron isn't water soluble, ... k

for hydroponics pH availability says iron is available all the way through up to pH 8 about. it tapers off as the pH climbs, but it's there

redox says otherwise. that the presence of O2 alone will remove iron from the system.

---

i missed something or something is poorly explained
or i'm looking at both pH & redox and wondering why they are arguing like this on nutrient availability in a soilless solution.

ammonia/ammonium changes are easy, it's a basic ratio, as the ph shifts one way, more is converted that way, as the ph shifts the other way, more move back, ... easy

iron is really screwing with me.
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Old 04-07-2014, 08:34 PM   #28
 
Pretty sure as far as iron goes plants produce chelating compounds to get the iron. Usually most all aquarium fertilizers come chelated. Iron is also a trace nutrient its not in very high demand.
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