Carbon source for denitrifying bacteria

[Habib]

That's the one I'm having a problem with Hab - good evening to you

Still afternoon here. Good morning to you.

Why do you have a problem with it?

Would you have problem if the food you would add would have a higher C:N and C:P ratios?

Or a lower N:C and P:C ratios (checking how your coffee is working ) ?

[Navyblue]

It's close to midnight here and I'm sipping my cold chocolate milk

So did the carbon dosing enables more efficient nutirent export through skimmer? or is it I am just skimming out what I have dosed?

[Bomber]

No but those things are balanced. Adding one in much higher ratios skews it artifically.
Like adding a lot of P to make N and C limiting. What happens when that artificailly added P crashes?
Then you have a abundance of P released and no where for it to go.

(coffee is not working yet. Yesterday was the first Monday of the month meeting - translated - Let's blind side the boss with a bunch of stuff we should have told him weeks ago.)

[Randy Holmes-Farley]

or is it I am just skimming out what I have dosed?

None of acetate/ethanol/sucrose will be directly skimmed out in significant quantities. So if you are getting more organics in the skimmate than before the carbon additions, then they are other organic materials. As such, they almost certainly contain some N and P, so it would be my opinion that you are not just skiming out what you added.

[Bomber]

Originally posted by Navyblue
From my earlier dosing I get a bacteria bloom from overdosing. And it is also noted in the German website of dosing vodka.

This you can skim out.

[Navyblue]

Will excess C cause more harm than excess N or P?

[Bomber]

Good question.

Since N and P are in many different forms and the C you're adding is in a simple form, I say definitely yes.

[Navyblue]

Can you explain why does simpler stuffs causes more harm?

[Bomber]

Rate of exchange.

If N and P are compounded you will not get a spike from them, you'll get a slow conversion and uptake.

The C you're adding is in a simple form that will cause a spike.

[Habib]

If N and P are compounded

If

But the concern is that not all is "compounded" but can present in the water colum as ions. This is what hobbyists measure.

If adding a simple carbon results in reduction of N and P then the water was limited with respect to carbon.

This justifies the addition of a simple carbon source.


The C you're adding is in a simple form that will cause a spike.


What kind of problems would that cause?

[Randy Holmes-Farley]

Will excess C cause more harm than excess N or P?

The "harms" as I understand them, are increased O2 consumption, and increased bacterial growth.

The harms of N and P are decreased calcification by corals, and increased algae growth.

Folks may have to decide for themselves which are more of a concern.

[Bomber]

But for this to work, both N and P have to be in a available form - floating around. Then how do you know how much sugar to add anyway.

[Habib]

Originally posted by Bomber
But for this to work, both N and P have to be in a available form - floating around. Then how do you know how much sugar to add anyway.

If N and P are measureable by hobbyist kits then they are available.

Any simple carbon source in excess will be converted to CO2.

[gtrestoration]

Everyone else seems to be drinking something... maybe I do to.

I've read the thread but just see reference to being C limited. What if the C is dosed and maybe only N OR P, but not both are available. Would this C dosing still be effective in reducing the P OR N that IS available?

SteveU

[Navyblue]

Originally posted by Bomber
Then how do you know how much sugar to add anyway.

If we can find out the minimum amount to dose while maintaining N or P at zero, I guess we are not dosing much in excess. Which is what I am doing now.

[Navyblue]

Originally posted by gtrestoration
I've read the thread but just see reference to being C limited. What if the C is dosed and maybe only N OR P, but not both are available. Would this C dosing still be effective in reducing the P OR N that IS available?

SteveU

I guess it will drive the growth of the strains of bacteria that need less of the lacking element and will eventually balanced out if the scenario is not too extreme.

[Jörg Kokott]

Originally posted by gtrestoration
Everyone else seems to be drinking something... maybe I do to.

I've read the thread but just see reference to being C limited. What if the C is dosed and maybe only N OR P, but not both are available. Would this C dosing still be effective in reducing the P OR N that IS available?

SteveU

Steve,

for heterotrophic aerobic bacteria C, N and O should be available following a certain ratio, which would be equivalent to the atomic ratio of these elements in the biomass.

Bacteria living in anoxic environemtns gain much less energy through anaerobic metabolism compared to aerobic bacteria. Thus, they grow/multiply much slower. Here, e.g. nitrate is majorily used as an electron acceptor in anaerobic metabolism. In aerobic bacteria, nitrogen is dominately used for nitrogen metabolism.

So, off course all these three major nutrients must be available, but you question cannot be answered that easy since we have both aerobic and anaerobic bacteria living in our tanks.

C-sources: I don't like sugars as C-sources as they are utilized by corals as well. The reason why e.g. Randy's corals turned brown after supplementing sugar is that coral metabolism is enhanced and this is coupled to both nitrogen ad phosphorus metabolism in these organism. So, increasing the nitrogen and phosphorus turnover in corals usually leads to an increase in zooxanthellae density, Same with host feeding.
If one adds sugars or better organic acids to the tank as coral organic nutrients the concentration of these compounds should be very low, otherwise it potentially leads to browing of corals.

Thus, as carbon sources for heterotrophic bacteria I'd prefer ethanol or methanol as these have been demonstrated to be easily utilized by bacteria but not by corals. In contrast, acetate as a carbon source for bacteria is also utilized by corals for fatty acid metabolism, so different organism are competing for this organic.

Concerning bacteria community structure:
In every ecosystem, so in reef tanks, the most competitive species will be dominating the organismal community in the ecosystem if the ecosystem's balance doesn't become disturbed. This is happening whether you dose a carbon source or not. So, while adding e.g. ethanol to reef tanks, one enhances the growth of those specimen which are most competitive under the given environmental conditions.

[Navyblue]

Is methanol toxic to fishes?

What about using sugar alcohos like lactitol or xylitol? Will corals absorb them?

[Navyblue]

Is methanol toxic to fishes?

What about using sugar alcohos like lactitol or xylitol? Will corals absorb them?

Vodka is expensive here, but we have do very cheap chinese rice wine used for cooking, can we dose this?

Will vodka or the rice wine that I mentioned contain some sugars or carbohydrates that will be absorbed by corals like sucrose?

[rsman]

ok so as i see this

adding C speads up coral metabolism, at the least this tends to turn corals brown, now is this in the end a bad thing?? its clearly not what i really want in my display tank, but do the corals now take up more N and P lowering the tanks N & P levels? does it cause the corals to grow faster? should I be adding this to my prop tanks? does the coloring come back?

[Jörg Kokott]

Ya, MeOH (methanol) is toxic both to humans and other vertebrates.
Therefore I'd prefer ethanol, which is much less toxic.

Don't think corals can utilize the substances you've mentioned, but actually I don't know.

Had some sake for myselfe some time ago, but don't know what's in it. I think it contains sugars as well, but I never tried.

You could also use analytical grade ethanol (>99%), but don't forget to dilute this stuff to 40% v/v (thus 400 mL EtOH + 600 mL H2O) or even less (20 or 30% v/v). Maybe it's cheaper?

[tonylamas]

Do fish have alcohol dehydrogenase? Most "higher" vertebrates do. Makes sense that fish would, but I don't really know if that generalization is really true.

This enzyme oxidizes ethanol to acetaldehyde...then acetic acid. Methanol is also oxidized by the same enzyme to formaldehyde, then formic acid. The formaldehyde is the toxin.

BTW: Here in the states, >95% ethanol is hard to get unless it has been denatured with benzene or methanol. Very highly regulated. I wouldn't but benzene in my tank. (Then again, I'm not putting ethanol in either, so...)

[Habib]

with benzene



Benzene is still allowed in the US to use it if there are alternatives?

[Navyblue]

Jorg:

Analytical grade ethanol is cheaper than vodka I guess, but I'm not quite comfortable in dosing non food stuffs though I know that they are purer. Although I do dose reagent grade potassium iodide .

I suppose there isn't much sugar in rice wine, I guess it will be my alternative, as it is so cheap and available.

Do you have any experimental data on ethanol dosing? do you have a guideline for me to serve as a reference?

Thanks.

[Randy Holmes-Farley]

The things in common use for denaturing ethanol in the US now include methanol, methyl isobutyl ketone (4-methyl-2-pentanone), isopropanol, ethyl acetate, gasoline, and "aliphatic hydrocarbons".