What carbon sources are more selectively digestible?

[taricha]

I wanted to share some observations and data. It was pretty undesirable, so I couldn't really continue past this point.

I did 80% (by carbon) of one carbon source and 10% two others. Vinegar, Methanol, Ethanol. The total amount of Carbon was set = 1mL of Vinegar / Gallon tank water.
I did 3 days of acclimation to the carbon dose and then 6 days of measurement. I did heavy methanol first, then 3 days of acclimation to heavy vinegar, then 6 days of measurement. I stopped at that point.
Black line is the NO3 level. Blue shows the NO3 consumption during heavy methanol phase (3.06ppm/day) - Red shows the consumption during heavy vinegar phase (1.93 ppm/day).

While it's tempting to say the methanol dose reduced NO3 more (which was what I was looking for) - Looking at the PO4 complicates things. PO4 got depleted around day 5, and after the PO4 was depleted around day 5, the NO3 consumption rate for methanol looked a bit more like the consumption rate for vinegar. If the tank had been equally P-deprived for both runs the differences in NO3 consumption might've been too small to care about.

Skimmer activity....
Every 2 days durning the 6-day measurement period, I poured oiut the liquid skimmate, and measured the volume. I also measured the increased mass of the skimmer cup after pouring to get a measure of how much solid sludge (anything that doesn't pour out) was accumulated every 2 days.

Again, maybe not different enough to care about after the P depletion by day 5.

I also at the end of the 6 measurement days wiped the glass with a paper towel on my fingertip on the same three 6" stretches of glass.
Left is after the heavy methanol, right is after the heavy vinegar.

This matches the eyeball assessment of clear films with methanol, but more photosynthetic films with vinegar. (this was mostly diatoms).

Now, back to the PO4 depletion and why I had to stop...
I hoped that I could target feed my corals live phyto, and they could eat bacteria from the carbon dosing and between those two they could avoid the harmful effects of zero PO4 and elevated NO3. Nope. Corals hated it. By the time I stopped the vinegar dose, there was tissue recession on multiple hard corals (montis mostly.)
Also, my GHA which is an everpresent slight annoyance grew really well by the end.
Also, during the vinegar dose, I developed a small dino outbreak, saw a couple of tiny strings on high flow surfaces. So hung a filter floss in front of a powerhead overnight, wrung it out the next day at noon.

This will be familiar to those who have dealt with dinos....

Brown filter, wring it out into a beaker, brown debris that pulls itself into clumps/strings. Under microscope dominated by ostreopsis dinos.

The thing that I'm more confident than most of the other stuff in making a connection here with this and other observations is that a heavy vinegar dose grows all manner of photosynthetic organisms, and if that's something you want to avoid, then your carbon source blend might want to be one that's low in acetic acid. maybe.

 

[Miami Reef]

I wanted to share some observations and data. It was pretty undesirable, so I couldn't really continue past this point.

I did 80% (by carbon) of one carbon source and 10% two others. Vinegar, Methanol, Ethanol. The total amount of Carbon was set = 1mL of Vinegar / Gallon tank water.
I did 3 days of acclimation to the carbon dose and then 6 days of measurement. I did heavy methanol first, then 3 days of acclimation to heavy vinegar, then 6 days of measurement. I stopped at that point.
Black line is the NO3 level. Blue shows the NO3 consumption during heavy methanol phase (3.06ppm/day) - Red shows the consumption during heavy vinegar phase (1.93 ppm/day).

While it's tempting to say the methanol dose reduced NO3 more (which was what I was looking for) - Looking at the PO4 complicates things. PO4 got depleted around day 5, and after the PO4 was depleted around day 5, the NO3 consumption rate for methanol looked a bit more like the consumption rate for vinegar. If the tank had been equally P-deprived for both runs the differences in NO3 consumption might've been too small to care about.

Skimmer activity....
Every 2 days durning the 6-day measurement period, I poured oiut the liquid skimmate, and measured the volume. I also measured the increased mass of the skimmer cup after pouring to get a measure of how much solid sludge (anything that doesn't pour out) was accumulated every 2 days.

Again, maybe not different enough to care about after the P depletion by day 5.

I also at the end of the 6 measurement days wiped the glass with a paper towel on my fingertip on the same three 6" stretches of glass.
Left is after the heavy methanol, right is after the heavy vinegar.

This matches the eyeball assessment of clear films with methanol, but more photosynthetic films with vinegar. (this was mostly diatoms).

Now, back to the PO4 depletion and why I had to stop...
I hoped that I could target feed my corals live phyto, and they could eat bacteria from the carbon dosing and between those two they could avoid the harmful effects of zero PO4 and elevated NO3. Nope. Corals hated it. By the time I stopped the vinegar dose, there was tissue recession on multiple hard corals (montis mostly.)
Also, my GHA which is an everpresent slight annoyance grew really well by the end.
Also, during the vinegar dose, I developed a small dino outbreak, saw a couple of tiny strings on high flow surfaces. So hung a filter floss in front of a powerhead overnight, wrung it out the next day at noon.

This will be familiar to those who have dealt with dinos....

Brown filter, wring it out into a beaker, brown debris that pulls itself into clumps/strings. Under microscope dominated by ostreopsis dinos.

The thing that I'm more confident than most of the other stuff in making a connection here with this and other observations is that a heavy vinegar dose grows all manner of photosynthetic organisms, and if that's something you want to avoid, then your carbon source blend might want to be one that's low in acetic acid. maybe.

Higher ethanol doses gave me clear stringy films, but high vinegar doses didn’t.

In my experience, I needed carbon from ethanol to reduce nitrates compared to acetate, but both work.

 

[Troylee]

I couldn’t answer your question because I’m no scientist by any means haha! I can say I started the zeo routine (zeo back, zeo food, zeo start) and zeolites in a reactor, my chateo took off like crazy! I mean a golf ball was a foot ball in 3-4 days! I pulled all my chateo because I felt it’s competing with the corals for the food source I’m supplying and I didn’t see a change in my corals.. it’s been 3 months with zeo and 2 without chateo and my corals seem to encrust faster then stalled out.. my po4 has bottomed out and my nitrates are holding steady at 15… I’m still playing with this and using a milk with bacteria and reef roids to compensate… I’ve always been a vodka/mb7 guy myself as it’s cheap and I might go back to that if this zeo doesn’t start to show improvement.

 

[Randy Holmes-Farley Verified Community Expert]

One interesting observation is that there really is no lag in the uptake of nitrate after initiating dosing, and that points to the lag that some report as perhaps being simply due to the slow ramp up in dose.

I'm not presently convinced there is ANY reason to slowly ramp up the dose, except to avoid overshooting. The idea of allowing bacteria to "expand" in numbers does not seem justified.

 

[Miami Reef]

I never took my time with ramping. I never saw the benefits. Corals act perfectly fine with a fast ramp.

 

[Dan_P]

I wanted to share some observations and data. It was pretty undesirable, so I couldn't really continue past this point.

I did 80% (by carbon) of one carbon source and 10% two others. Vinegar, Methanol, Ethanol. The total amount of Carbon was set = 1mL of Vinegar / Gallon tank water.
I did 3 days of acclimation to the carbon dose and then 6 days of measurement. I did heavy methanol first, then 3 days of acclimation to heavy vinegar, then 6 days of measurement. I stopped at that point.
Black line is the NO3 level. Blue shows the NO3 consumption during heavy methanol phase (3.06ppm/day) - Red shows the consumption during heavy vinegar phase (1.93 ppm/day).

While it's tempting to say the methanol dose reduced NO3 more (which was what I was looking for) - Looking at the PO4 complicates things. PO4 got depleted around day 5, and after the PO4 was depleted around day 5, the NO3 consumption rate for methanol looked a bit more like the consumption rate for vinegar. If the tank had been equally P-deprived for both runs the differences in NO3 consumption might've been too small to care about.

Skimmer activity....
Every 2 days durning the 6-day measurement period, I poured oiut the liquid skimmate, and measured the volume. I also measured the increased mass of the skimmer cup after pouring to get a measure of how much solid sludge (anything that doesn't pour out) was accumulated every 2 days.

Again, maybe not different enough to care about after the P depletion by day 5.

I also at the end of the 6 measurement days wiped the glass with a paper towel on my fingertip on the same three 6" stretches of glass.
Left is after the heavy methanol, right is after the heavy vinegar.

This matches the eyeball assessment of clear films with methanol, but more photosynthetic films with vinegar. (this was mostly diatoms).

Now, back to the PO4 depletion and why I had to stop...
I hoped that I could target feed my corals live phyto, and they could eat bacteria from the carbon dosing and between those two they could avoid the harmful effects of zero PO4 and elevated NO3. Nope. Corals hated it. By the time I stopped the vinegar dose, there was tissue recession on multiple hard corals (montis mostly.)
Also, my GHA which is an everpresent slight annoyance grew really well by the end.
Also, during the vinegar dose, I developed a small dino outbreak, saw a couple of tiny strings on high flow surfaces. So hung a filter floss in front of a powerhead overnight, wrung it out the next day at noon.

This will be familiar to those who have dealt with dinos....

Brown filter, wring it out into a beaker, brown debris that pulls itself into clumps/strings. Under microscope dominated by ostreopsis dinos.

The thing that I'm more confident than most of the other stuff in making a connection here with this and other observations is that a heavy vinegar dose grows all manner of photosynthetic organisms, and if that's something you want to avoid, then your carbon source blend might want to be one that's low in acetic acid. maybe.

Just to confirm Randy’s observation, there was no lag time in dosing and nitrate reduction?

 

[Dan_P]

I wanted to share some observations and data. It was pretty undesirable, so I couldn't really continue past this point.

I did 80% (by carbon) of one carbon source and 10% two others. Vinegar, Methanol, Ethanol. The total amount of Carbon was set = 1mL of Vinegar / Gallon tank water.
I did 3 days of acclimation to the carbon dose and then 6 days of measurement. I did heavy methanol first, then 3 days of acclimation to heavy vinegar, then 6 days of measurement. I stopped at that point.
Black line is the NO3 level. Blue shows the NO3 consumption during heavy methanol phase (3.06ppm/day) - Red shows the consumption during heavy vinegar phase (1.93 ppm/day).

While it's tempting to say the methanol dose reduced NO3 more (which was what I was looking for) - Looking at the PO4 complicates things. PO4 got depleted around day 5, and after the PO4 was depleted around day 5, the NO3 consumption rate for methanol looked a bit more like the consumption rate for vinegar. If the tank had been equally P-deprived for both runs the differences in NO3 consumption might've been too small to care about.

Skimmer activity....
Every 2 days durning the 6-day measurement period, I poured oiut the liquid skimmate, and measured the volume. I also measured the increased mass of the skimmer cup after pouring to get a measure of how much solid sludge (anything that doesn't pour out) was accumulated every 2 days.

Again, maybe not different enough to care about after the P depletion by day 5.

I also at the end of the 6 measurement days wiped the glass with a paper towel on my fingertip on the same three 6" stretches of glass.
Left is after the heavy methanol, right is after the heavy vinegar.

This matches the eyeball assessment of clear films with methanol, but more photosynthetic films with vinegar. (this was mostly diatoms).

Now, back to the PO4 depletion and why I had to stop...
I hoped that I could target feed my corals live phyto, and they could eat bacteria from the carbon dosing and between those two they could avoid the harmful effects of zero PO4 and elevated NO3. Nope. Corals hated it. By the time I stopped the vinegar dose, there was tissue recession on multiple hard corals (montis mostly.)
Also, my GHA which is an everpresent slight annoyance grew really well by the end.
Also, during the vinegar dose, I developed a small dino outbreak, saw a couple of tiny strings on high flow surfaces. So hung a filter floss in front of a powerhead overnight, wrung it out the next day at noon.

This will be familiar to those who have dealt with dinos....

Brown filter, wring it out into a beaker, brown debris that pulls itself into clumps/strings. Under microscope dominated by ostreopsis dinos.

The thing that I'm more confident than most of the other stuff in making a connection here with this and other observations is that a heavy vinegar dose grows all manner of photosynthetic organisms, and if that's something you want to avoid, then your carbon source blend might want to be one that's low in acetic acid. maybe.

How did your ratio of carbon added to nitrate removed compare to Lasse’s upflow carbon dosing to the substrate ratio? Were the rates comparable aside from any ratio differences?

 

[taricha]

In my experience, I needed carbon from ethanol to reduce nitrates compared to acetate, but both work.

did you mean to say *more* carbon from ethanol, or *less* carbon from ethanol as compared to acetate?

Just to confirm Randy’s observation, there was no lag time in dosing and nitrate reduction?

right. There was no "ramp up" in NO3 consumption. It didn't get better at consuming NO3 after a week than it did after a day.
My system had organisms that could respond to the carbon sources I used in <24hr. So if the population had to scale up, they could apparently do so quickly.

How did your ratio of carbon added to nitrate removed compare to Lasse’s upflow carbon dosing to the substrate ratio? Were the rates comparable aside from any ratio differences?

I don't actually have a current baseline of what my NO3 consumption looks like with zero Carbon dose so it's a little hard to say... but I'll assume it might be close to zero, and make an estimate.

 

[taricha]

This was not what I was trying to say...

... a heavy vinegar dose grows all manner of photosynthetic organisms, and if that's something you want to avoid, then your carbon source blend might want to be one that's low in acetic acid.

I meant that films/surface growths look more "photosynthetic colored" with vinegar and look less pigmented with methanol (and other alcohols I'm guessing). That can be from growing more of one, less of another, or some combination.
My interpretation is that colorless bacterial films are relatively more prevalent with methanol dosing than vinegar, and maybe the photosynthetic stuff does better under vinegar too.


basically closer to this observation.

Higher ethanol doses gave me clear stringy films, but high vinegar doses didn’t.

 

[Miami Reef]

did you mean to say *more* carbon from ethanol, or *less* carbon from ethanol as compared to acetate?

I was trying to fix my wording, but I accidentally removed a word.

I was trying to say I needed more acetate to reduce the same amount of nitrates compared to ethanol.

I use the ethanol is 8x more potent recipe. Dosing 15mL of ethanol in my tank absolutely tanks nitrates, but I need about 200mL of vinegar for a similar effect. I still feel like 15mL of vodka is stronger than 200mL of acetate.

In a 260 gallon tank.

I wrote about this to Randy a few months ago. I will try to find it.

 

[taricha]

How did your ratio of carbon added to nitrate removed compare to Lasse’s upflow carbon dosing to the substrate ratio? Were the rates comparable aside from any ratio differences?

Lasse's is way better. I got at best, 8.9 Moles of Carbon input per 1 mole of NO3 consumed.

Lasse's was like 2:1

Like 2 moles of Carbon removes 1 mole of Nitrogen, good.

The slope of the above right graph ~0.5 moles of NO3 per mole of Carbon is actually possible - at least it's well within what's allowed by the below equation : up to 12 mole NO3 removed per 10 mole of Carbon added, or 1.2 NO3 per Carbon.

 

[jason2459]

What carbon sources might be a good option in terms of growing bacteria well, but being of low/no value to algae?

Well, I'll throw back out there a carbon source that could be localized in a reactor with the use of 'bio" pellets. I tried that out for a bit with shapelock in a canister filter.

 

[Dan_P]

Lasse's is way better. I got at best, 8.9 Moles of Carbon input per 1 mole of NO3 consumed.

Lasse's was like 2:1

Nice.

I don’t recall what I obtained in my observations of my aquarium consumption ratio years ago but it was large too. Lasse’s low ratio is almost like the carbon is going to make protein and none to generating energy (CO2).

 

[taricha]

Well, I'll throw back out there a carbon source that could be localized in a reactor with the use of 'bio" pellets. I tried that out for a bit with shapelock in a canister filter.

To ask a dumb question, when PHA gets digested by microbes, do they just work on the immobilized solids, or do they chop it into soluble bits that go into the water?

I don’t recall what I obtained in my observations of my aquarium consumption ratio years ago but it was large too.

Yeah, when I ran your numbers for vinegar by comparison I got well over 10, like 40:1.

Lasse’s low ratio is almost like the carbon is going to make protein and none to generating energy (CO2).

Seems like the denitrification equation gives you plenty of bang for the (carbon) buck to explain Lasse's results.

Here’s the balanced denitrification for ethanol.

12 NO3– + 5 CH3CH2OH + 12 H+ → 10 CO2 + 6 N2 + 21 H2O

 

[jason2459]

To ask a dumb question, when PHA gets digested by microbes, do they just work on the immobilized solids, or do they chop it into soluble bits that go into the water?

Seems like a good question. I don't know. I looked back on my DIY Shapelock thread on RC and I did notice white haze on the glass along with the bacteria in the reactor. I also totally forgot that at one point I tested the shape lock by directly placing it in the substrate based on some patent information. I noticed a lot more "pod" activity that I assumed was them consuming the bacteria.

 

[Randy Holmes-Farley Verified Community Expert]

To ask a dumb question, when PHA gets digested by microbes, do they just work on the immobilized solids, or do they chop it into soluble bits that go into the water?

I don’t know the answer, but I expect it’s the latter. I don’t think they can hope to contain every monomer that gets released, but whether that is a large fraction or a small one, I don’t know.

 

[StubbyAcro]

From @AquaBiomics, Dr Eli mentioned what families of bacteria fueled by carbon dosing.

We do see signatures of carbon dosing in hobbyist aquariums. A few families that we well known to respond to nutrient dosing from the literature, also are present at high levels in many tanks that carbon dose.

When we look at these tanks at the species level we often find that carbon dosing promotes the growth of specific bacteria associated with the fish gut microbiome. In other words, in a heavily carbon dosed tank the dominant bacteria are often fish poop bacteria. But those are not pathogens, they're normal members of the fish gut community even if they're not normally present at high levels in the water.

We don't generally see increased Vibrionaceae or Rhodobacteraceae in carbon dosed tanks. This may suggest we shouldnt worry too much about carbon dosing in terms of pathogens. On the other hand, we do sometimes see elevated Alteromonadaceae which is a group that includes some pathogens, and a group where standard genetic markers have limited resolution. So I can't rule it out, only say that its not the major effect we find.

In general, carbon dosing appears to heavily alter the community and for that reason I think it should probably be used more cautiously in the hobby than it currently is. It sounds like you're approaching this with the appropriate level of caution.

I especially am not a fan of hidden carbon in many aquarium products that don't list their full ingredients. Its not that I'm saying noone should add any carbon - just that the type and amounts have a very large impact on the bacterial community so my gut feeling is we should probably be as cautious about adding carbon to our tanks as we are when adding any other nutrient.

None of this is intended to say "don't carbon dose the system you mentioned" -- just my thoughts on carbon dosing in general based on what we've seen in these data.

 

[taricha]

I looked back on my DIY Shapelock thread on RC and I did notice white haze on the glass along with the bacteria in the reactor.

Interesting, sounds consistent with the idea that Randy mentioned - the monomers broken off from biopellets would go into the water and it might be enough to drive bacterial growth elsewhere.
I think @Dan_P would point out that a well-fed biofilm sheds bacteria into the water constantly. It may be best to think of bio-pellets as "mostly local" carbon dosing.

 

[taricha]

Thanks for sharing that, @StubbyAcro
The distinction he makes between fish gut bacteria and more typically pathogenic groups is fascinating. We are often dosing carbon sources that are very quickly digestible, so it's not crazy to wonder if pathogens which by nature would be capable of very rapid growth (infections move fast) might be responding to some of our carbon sources. So it's interesting he has some data pointing against that.

"Its not that I'm saying noone should add any carbon - just that the type and amounts have a very large impact on the bacterial community so my gut feeling is we should probably be as cautious about adding carbon to our tanks as we are when adding any other nutrient."

Big picture, this part about the type of carbon having a big effect is my main point here. The rule of thumb of 8mL vinegar = 1mL of vodka (and other carbon conversions) suggests an interchangeability between different sources which obscures that it looks like they may be used very differently and observers find they affect the tank in different visible ways.
Maybe the default presumption should be that each carbon source is it's own different food (like nori vs mysis). Assume each will affect your tank organisms differently even at the same Carbon level. Since measurements of these effects seem hard to do, make careful observations and note what others have seen with the same carbon source.
Choosing carbon sources like this may really be the best way to go about it....

It is a very intersting question indeed. The carbon source for our liquid organic carbon dosing products was found simply by experimenting. Which carbon source has the best effect to the overall tank condition without causing excessive slimy bacteria coatings?

find a carbon source that has fit the criteria you are looking for in other systems and watch closely to see if it does the same in your tank.

 

[Dan_P]

Interesting, sounds consistent with the idea that Randy mentioned - the monomers broken off from biopellets would go into the water and it might be enough to drive bacterial growth elsewhere.
I think @Dan_P would point out that a well-fed biofilm sheds bacteria into the water constantly. It may be best to think of bio-pellets as "mostly local" carbon dosing.

A popular explanation is that bacteria biofilms growing on the pellets are abraded from the pellet in the reactor and removed by skimming (nitrogen export). The remote growth is not covered by this explanation. Randy’s idea explains the remote growth of bacteria. I will add that there is a possibility that the remote growth is a coincidence. When starving a system of nitrogen (nitrate reduction), organisms that depend on that nitrogen are dying and becoming bacteria food.