What do we really know about vinegar (carbon) dosing?

[KGV]

These are just some thoughts I had when I recently started carbon dosing. You have all read it before; the idea is to add a carbon source, which feeds the otherwise carbon-limited population of bacteria, which causes a reduction in N and P. And bacteria get skimmed out by the skimmer. But how much scientific evidence is there for this mechanism?

Just one observation: Why does the skimmer go bonkers when vinegar dosing? When I added bottle bacteria before, this did not happen. Does vinegar act as a flocculant instead? Also, the sheer mass of skimmed bacteria must be really high to reduce N and P significantly. When you have a refugium, you can grab a couple of handfuls of chaeto, and its dry weight is considerable. We know approx. the N and P content of chaeto and, hence, we know how much N and P we are removing. But if you were to dry out the skimmate, I wonder if you would get a lot of dry-weight substance out. Perhaps many of the organisms that you grow with vinegar do not need to leave via the skimmate? Then, you could imagine binding up N and P in sponges and rock-bound bacteria. Anyhow, these are some thoughts to start a critical discussion. References to literature would be useful. @Randy Holmes-Farley @Lasse @taricha @Dan_P.

 

[Randy Holmes-Farley Verified Community Expert]

Vinegar cannot act as a flocculant. All flocculants need at least two binding sites to attach to something else. Vinegar (acetate) lacks such multiple binding sites.

I would not assume the bacteria are the only user of acetate. Bacteria may not even be the primary user. Corals, sponges, etc all can use acetate.

 

[Lasse]

I dose ethanol below my deep sand bed and I totally control my NO3 concentrations that way but the PO4 - nada

The major control of my NO3 is not done by bacteria growth - its done by bacteria that use NO3 as an electron acceptor in oxygen free environment - ethanol is the electron donor in the same process - neither act as building blocks in this process.

However the whole process start with that ethanol act as an organic carbon source for heterotrophic bacteria in such a high grade that they consume all oxygen - In this process some organic carbon, NO3 and PO4 will be transformed into biomass - but not so much. When oxygen is limited or absent - some heterotrophic bacteria swing over and use NO3 instead for oxygen in the metabolism - hence convert NO3 into N2 gas (with help of some other steps but N2 is the final waste) This is the major part of NO3 reducing in my reversed flow DSB

I have always been sceptic to the claim that heterotrophic bacteria is able to take up so much dissolved PO4 and NO3 that it makes a difference.

On the contrary - if DOC is available, the bacteria will be able to eat more solid organic matter - and thus release both NH3/NH4 and PO4 from their organic origin (proteins and phosphorus organic compounds) in the solid organic matter

Sincerely Lasse

 

[KGV]

I dose ethanol below my deep sand bed and I totally control my NO3 concentrations that way but the PO4 - nada

The major control of my NO3 is not done by bacteria growth - its done by bacteria that use NO3 as an electron acceptor in oxygen free environment - ethanol is the electron donor in the same process - neither act as building blocks in this process.

However the whole process start with that ethanol act as an organic carbon source for heterotrophic bacteria in such a high grade that they consume all oxygen - In this process some organic carbon, NO3 and PO4 will be transformed into biomass - but not so much. When oxygen is limited or absent - some heterotrophic bacteria swing over and use NO3 instead for oxygen in the metabolism - hence convert NO3 into N2 gas (with help of some other steps but N2 is the final waste) This is the major part of NO3 reducing in my reversed flow DSB

I have always been sceptic to the claim that heterotrophic bacteria is able to take up so much dissolved PO4 and NO3 that it makes a difference.

On the contrary - if DOC is available, the bacteria will be able to eat more solid organic matter - and thus release both NH3/NH4 and PO4 from their organic origin (proteins and phosphorus organic compounds) in the solid organic matter

Sincerely Lasse

Thanks Lasse. Just one thought; the molecular weight of ethanol and NO3 is larger than O2. How do you get NO3 to these O2-free zones, and keep them O2-free?

 

[jda]

All of my older, undisturbed sandbeds will chew through any amount of nitrate and just leave a trace. They do nothing for po4. They have to be deep enough so that the o2 gets used up by the processes on the top. 3" is usually enough for my purposes. Deeper is better, but 0.10 of no3 is enough for me and I don't want to use up 3 more inches of tank space to get to the 6" that many used to like. The deeper zones have different pH but also different temperatures with the low flow and stuff and the water makes it down there on it's own. The temp in the bottom of my sandbed is often in the 60s with the tank water being 76 - this alone can move some water. Some use a pump like Lasse does.

In the end, we do not know much, IMO. There was a PhD in Bacteriology on here a while back and he did some tests that seemed to indicate that most of what you skim is dead material - short lived bacteria that grow and die quickly - you skim some of them and some get recycled in the tank. I think that some assume that some sort of AOB, NOB or other bacteria with an important function just multiply, but I doubt it. It is as possible that OC grows slaves to the system just to grow, die and get removed with filtration that might not have much other use. Who knows if he was right.

 

[Koty]

I dose KZ Spongepower (which is concentrated acetic acid probably fortified wih Mn) and two other Tropic marin products. The main goal of carbon dosing IMO iis not nitrate and phosphate elimination but to support sponges, corals, and the bacterial population that is key to keeping the tank alive and happy.

 

[Randy Holmes-Farley Verified Community Expert]

That’s primarily why I dosed it as well: to provide food for corals and sponges and such, both directly and indirectly via bacteria.

 

[Lasse]

Thanks Lasse. Just one thought; the molecular weight of ethanol and NO3 is larger than O2. How do you get NO3 to these O2-free zones, and keep them O2-free?

Its a rather delicate process. Water and DOC is coming into the plenum. DOC make the heterotrophic bacteria to grow and propagate. The biomass get as large that it somewhere in the gravel all oxygen is gone and the bacteria can use DOC both for growth and as an electron donor but in absence of O2 switch to NO3 as electron acceptor. The water that come from the DSB out in my refugium will be more or less without O2 but a rest of NO3 with it. The DOC should have been consumed during the pass of the DSB. Below a principal drawing of my system. It is in the refugium. The trick is to balance water flow and DOC addition so that bacteria consume all the oxygen but there is an excess of DOC sufficient to do some denitrification higher up in the DSB. When the system is in balance and has the desired NO3 concentration, the loss of NO3 through DSB must be as large as the entire production of NO3 in the aquarium,

Sometimes O got to much bacteria and sediment in the plenum - I use a tube and suck up most of it periodically

Sincerely Lasse

 

[KGV]

Its a rather delicate process. Water and DOC is coming into the plenum. DOC make the heterotrophic bacteria to grow and propagate. The biomass get as large that it somewhere in the gravel all oxygen is gone and the bacteria can use DOC both for growth and as an electron donor but in absence of O2 switch to NO3 as electron acceptor. The water that come from the DSB out in my refugium will be more or less without O2 but a rest of NO3 with it. The DOC should have been consumed during the pass of the DSB. Below a principal drawing of my system. It is in the refugium. The trick is to balance water flow and DOC addition so that bacteria consume all the oxygen but there is an excess of DOC sufficient to do some denitrification higher up in the DSB. When the system is in balance and has the desired NO3 concentration, the loss of NO3 through DSB must be as large as the entire production of NO3 in the aquarium,

Sometimes O got to much bacteria and sediment in the plenum - I use a tube and suck up most of it periodically

Very neat design. But not for mortals.

 

[Lasse]

Very neat design. But not for mortals.

But I`m 74 years old and feel very mortal ;)

Sincerely Lasse

 

[Miami Reef]

Why does the skimmer go bonkers when vinegar dosing?

Cheap distilled white vinegar will not cause skimmer to go bonkers.

 

[KGV]

Cheap distilled white vinegar will not cause skimmer to go bonkers.

I use lab grade acetic acid. Bonkers was the wrong word. More foamy than usual for sure.

 

[Lasse]

I use lab grade acetic acid. Bonkers was the wrong word. More foamy than usual for sure.

It could have with altered surface tension to do.

Sincerely Lasse

 

[Miami Reef]

I use lab grade acetic acid. Bonkers was the wrong word. More foamy than usual for sure.

That’s the issue. You need distilled white vinegar.

 

[Koty]

Vinegar is 5% acetic acid. Lab grade (glacial) is 100%. Foam is simply because thete are more bacteria on the water column.

 

[Lasse]

Foam is simply because thete are more bacteria on the water column.

Do you mean that there are more pelagic bacteria in the water column and that they are continuously skimmed out?

Sincerely Lasse

 

[KGV]

But I`m 74 years old and feel very mortal ;)

Sincerely Lasse

@Lasse . I will collect everything everything you ever posted on R2R, make a language model of it, and you will live forever!

 

[KGV]

That’s the issue. You need distilled white vinegar.

But I did dilute the vinegar to 5% though. And I add it to my CaCl2 container for two-part dosing.

 

[KGV]

Do you mean that there are more pelagic bacteria in the water column and that they are continuously skimmed out?

Sincerely Lasse

Without a way to measure bacteria, it is not possible to tell.

 

[KGV]

This article is a good start, but if I had time, I would love to re-test these things:
https://reefs.com/magazine/bacteria...ing-and-granular-activated-carbon-filtration/