Aquarist007
New member
with all the discussion here--excelllent I might add---I am glad I am running a dsb remotely in a refugium. Any problems in 5-7 years I will be able to take care off with out afffecting the display tank.
DSB Diagram -- Seeking Consensus
- Thread starter Whys
- Start date
with all the discussion here--excelllent I might add---I am glad I am running a dsb remotely in a refugium. Any problems in 5-7 years I will be able to take care off with out afffecting the display tank.
Whys,
My conversational statement to Jenglish suggests a tank can be run without a sand bed,which is very true.
The deep sand bed of Juabert is only one approach to nitrification and denitrification, one with some serious flaws in various applications. The most common of which is not keeping the sand live and not replenishing some live sand periodically or providing another force such as high advective flow and obstacles such as live rock on the sand to help advection account for the limits of diffusion.
I personally like a 4 inch plus bed for the aesthetics and because certain animals do better with such a bed( certain wrasses and anemomes for example) .Not everyone feels that way and many prefer less substrate ,more flow and alternate methods. Maintenance can be a hassle with in display beds and without it they can become nutrient sinks. Again if it is kept live it should do fine.I have one 7 year old bed in one of my tanks.
Many also employ remote deep sand beds,macroalgae refugia,gac,skimming ,carbon dosing , dentirators, upsidedown sand beds. algal turf scrubbers, reverse undergravel flitration and I'm sure I've left out a few.
The study is pretty clear that depth and grain size alone are of minimal relevance for denitrification.Layering alone even at 1 inch doesn't seem to predict the level of nitrate reduction.
.Advective flow and the upwelling it produces pulls water into the sand and channeling and transport by orgainisms have a lot to do with making deeper areas functional.
It is very difficult to show a true representation of what's occurring in simple chart format because the process is complex and variable. It's not arcane: just has a number of moving parts dancing to different steps at different times and reacting to to one another.
Any presentation on a deep bed should be as one of many biofiltration options for a reef tank and not give the impression of a suggested best practice, in my opinion.
As for the draft:
Ammonia and ammonium are both oxidized by the nitrifiers. Ammonia (NH3) is the toxic form, Ammonium(NH4) is pretty benign as far as toxicity goes. These two forms of ammonia speciate
(chage back and forth) in as little time as a billionth of a second. As ph drops ammonium increases and ammonia decreases due to the greater availability of H+ions in the at lower ph values. I should also note that while detritus contributes some ammonia/ammonium , excretions by organisms( expelling excessive nitrogen intake) such as urea probably contribute even more in a high bioload tank.
The bacteria perfoming denitrification are by and large the same heterotrophs that are performing nitrification . Most do well in the presence of oxygen . They first perform aerobic activity to oxidize ammonia/ammonium by adding the(O2 ) to nitrite (NO2) and then the 3rd oxygen molecule to (NO3). The H is set free in this process. These bacteria then go back to the well when oxygen is depleted and perform anaerobic activity and use the O3 in the nitrate. When that's gone they turn to other oxygen sources such as SO4 .
My conversational statement to Jenglish suggests a tank can be run without a sand bed,which is very true.
The deep sand bed of Juabert is only one approach to nitrification and denitrification, one with some serious flaws in various applications. The most common of which is not keeping the sand live and not replenishing some live sand periodically or providing another force such as high advective flow and obstacles such as live rock on the sand to help advection account for the limits of diffusion.
I personally like a 4 inch plus bed for the aesthetics and because certain animals do better with such a bed( certain wrasses and anemomes for example) .Not everyone feels that way and many prefer less substrate ,more flow and alternate methods. Maintenance can be a hassle with in display beds and without it they can become nutrient sinks. Again if it is kept live it should do fine.I have one 7 year old bed in one of my tanks.
Many also employ remote deep sand beds,macroalgae refugia,gac,skimming ,carbon dosing , dentirators, upsidedown sand beds. algal turf scrubbers, reverse undergravel flitration and I'm sure I've left out a few.
The study is pretty clear that depth and grain size alone are of minimal relevance for denitrification.Layering alone even at 1 inch doesn't seem to predict the level of nitrate reduction.
.Advective flow and the upwelling it produces pulls water into the sand and channeling and transport by orgainisms have a lot to do with making deeper areas functional.
It is very difficult to show a true representation of what's occurring in simple chart format because the process is complex and variable. It's not arcane: just has a number of moving parts dancing to different steps at different times and reacting to to one another.
Any presentation on a deep bed should be as one of many biofiltration options for a reef tank and not give the impression of a suggested best practice, in my opinion.
As for the draft:
Ammonia and ammonium are both oxidized by the nitrifiers. Ammonia (NH3) is the toxic form, Ammonium(NH4) is pretty benign as far as toxicity goes. These two forms of ammonia speciate
(chage back and forth) in as little time as a billionth of a second. As ph drops ammonium increases and ammonia decreases due to the greater availability of H+ions in the at lower ph values. I should also note that while detritus contributes some ammonia/ammonium , excretions by organisms( expelling excessive nitrogen intake) such as urea probably contribute even more in a high bioload tank.
The bacteria perfoming denitrification are by and large the same heterotrophs that are performing nitrification . Most do well in the presence of oxygen . They first perform aerobic activity to oxidize ammonia/ammonium by adding the(O2 ) to nitrite (NO2) and then the 3rd oxygen molecule to (NO3). The H is set free in this process. These bacteria then go back to the well when oxygen is depleted and perform anaerobic activity and use the O3 in the nitrate. When that's gone they turn to other oxygen sources such as SO4 .
Aquarist007
New member
TMZ--can you point me to some articles on advection?
121
Member
Hi TRFM,
I'm trying to understand what bacteria are actually doing in a sand.
I'm trying to understand what bacteria are actually doing in a sand.
Why does the bacteria use up organic carbon first before using up N03? I'm assuming their using organic carbon faster to build their new bodies as they multiply.
That didn't make any sense to me at all. Could you explain this a little more please?
So ethanol is an organic carbon?
Ok,
Let me chime in. The 4" bed depth I always suggest for a DSB is not finite but has shown to be a good approximation for a bed that effectively removes nitrates without a large degree of sulfate reduction. Since the method became popular in the mid to late 1990's much juggling of bed depth was done.
We need two things for denitrification; oxygen levels of <0.5 ppm and a supply of carbon to act as an electron receptor (reducing agent) for the bacteria to do their jobs. Nitrate reducing bacteria, unlike nitrification bacteria, are not a specialize group. Normal hertrotrophs, present in the upper bed, readily adapt to nitrate reduction when nascent oxygen levels fall below a half part per million.
I disagree with Tom that denitrifiction occurs to any major extent in a shallow bed. Oxygen penetration occurs to a depth of at least an inch and one-half and aerobic levels are probably maintained for at least twice that level in a DSB. Don't forget, we are dealing with a gradient effect here and a bed does not go from aerobic to anoxic in a single defined area. It also depends on the amount of oxygen being consumed at higher levels in the bed plus the degree of waste loading into the substrate. Tom may be indeed be correct, that in a heavily loaded tank, a 2" bed, may have oxygen levels in the anoxic zone, Yet, this is a hobby, and it is unrealistic to have the new aquarist do a mass balance of nutrient import on the tank. That is why we suggest the 4" bed as a "one size suits all" solution.
Ryan asks about even deeper beds. Again it would be hard to tell if there are tanks so lightly nutrient loaded that the bed needs to be deeper than 4". There is a very real danger of having a very deep bed deplete both oxygen and nitrate to such an extent that sulfate reduction becomes the major factor in waste degredation. That is that toxic zone you show in your diagram. Now, it is true that people use coil "desulfinators" on their tanks but the flow in that type of unit is so slow that hydogen sulfide production is at very low levels. In a DSB, covering the entire tank's bottom, hydrogen sulfide build up would be a cause for concern. Plenum systems do use 6" or deeper beds as the plenum reportedly allow deeper oxygen penetration into the bed. That may be true but using such a deep bed is taking a chance as well as using valuable space in the tank. To me it is not justified.
I came to this thread mainly to see the diagram and supporting comments. I'm still thinking about that but I do think the model need to place more emphasis on the role of bacteria in the sand bed. In the shallow bed hetrotrophic bacteria hydrolyze and consume waste with the release of ammonia. Their contribution to waste reduction probably far exceeds that of the higher level scavengers in the marine tank. Also, since we are using the medical terminology we have Oxic, high oxygen content- Anoxic, reduced oxygen content- Hypoxic, oxygen absent. The lower level in the diagram should therefor read hypoxic, rather than, anoxic.
I'll add more after I check my regular forums.
Let me chime in. The 4" bed depth I always suggest for a DSB is not finite but has shown to be a good approximation for a bed that effectively removes nitrates without a large degree of sulfate reduction. Since the method became popular in the mid to late 1990's much juggling of bed depth was done.
We need two things for denitrification; oxygen levels of <0.5 ppm and a supply of carbon to act as an electron receptor (reducing agent) for the bacteria to do their jobs. Nitrate reducing bacteria, unlike nitrification bacteria, are not a specialize group. Normal hertrotrophs, present in the upper bed, readily adapt to nitrate reduction when nascent oxygen levels fall below a half part per million.
I disagree with Tom that denitrifiction occurs to any major extent in a shallow bed. Oxygen penetration occurs to a depth of at least an inch and one-half and aerobic levels are probably maintained for at least twice that level in a DSB. Don't forget, we are dealing with a gradient effect here and a bed does not go from aerobic to anoxic in a single defined area. It also depends on the amount of oxygen being consumed at higher levels in the bed plus the degree of waste loading into the substrate. Tom may be indeed be correct, that in a heavily loaded tank, a 2" bed, may have oxygen levels in the anoxic zone, Yet, this is a hobby, and it is unrealistic to have the new aquarist do a mass balance of nutrient import on the tank. That is why we suggest the 4" bed as a "one size suits all" solution.
Ryan asks about even deeper beds. Again it would be hard to tell if there are tanks so lightly nutrient loaded that the bed needs to be deeper than 4". There is a very real danger of having a very deep bed deplete both oxygen and nitrate to such an extent that sulfate reduction becomes the major factor in waste degredation. That is that toxic zone you show in your diagram. Now, it is true that people use coil "desulfinators" on their tanks but the flow in that type of unit is so slow that hydogen sulfide production is at very low levels. In a DSB, covering the entire tank's bottom, hydrogen sulfide build up would be a cause for concern. Plenum systems do use 6" or deeper beds as the plenum reportedly allow deeper oxygen penetration into the bed. That may be true but using such a deep bed is taking a chance as well as using valuable space in the tank. To me it is not justified.
I came to this thread mainly to see the diagram and supporting comments. I'm still thinking about that but I do think the model need to place more emphasis on the role of bacteria in the sand bed. In the shallow bed hetrotrophic bacteria hydrolyze and consume waste with the release of ammonia. Their contribution to waste reduction probably far exceeds that of the higher level scavengers in the marine tank. Also, since we are using the medical terminology we have Oxic, high oxygen content- Anoxic, reduced oxygen content- Hypoxic, oxygen absent. The lower level in the diagram should therefor read hypoxic, rather than, anoxic.
I'll add more after I check my regular forums.
Whys
New member
Okay, so now you tell me... should it be ammonium or ammonia in the red arrow? I would not have thought this a difficult question. I have always seen other diagrams use ammonia, and apparently that is the toxic form. Change it back to ammonia?
Tom, the diagram is not weighted for bio activity, simply linear processing. I also have no idea how to represent weighted activity within the diagram, but am willing to entertain graphical suggestions.
Also, I don't believe oxic, hypoxic, and anoxic are specifically medical terms. Originally I wanted to put hyperhypoxic in there and that is a medical term, but ultimately gave up on that idea. The remaining terms are correct. Hypoxic means very low oxygen and anoxic means devoid of oxygen. See what borrowed terms have done for your field of study?
I ask again, ammonium or ammonia?
Tom, the diagram is not weighted for bio activity, simply linear processing. I also have no idea how to represent weighted activity within the diagram, but am willing to entertain graphical suggestions.
Also, I don't believe oxic, hypoxic, and anoxic are specifically medical terms. Originally I wanted to put hyperhypoxic in there and that is a medical term, but ultimately gave up on that idea. The remaining terms are correct. Hypoxic means very low oxygen and anoxic means devoid of oxygen. See what borrowed terms have done for your field of study?
I ask again, ammonium or ammonia?
Whys
New member
All I'm saying is that the purpose of the diagram is not for considering comparative techniques. It's purpose is to explain a DSB within its own context. Newbies can make their own comparisons once they actually know what it is they're looking at.
That's why we need to stay focused.
Agreed. That is also not the intention of the diagram or text. The only thing I'm advocating is a generalized knowledge of the concepts involved and proper terminology. This is what a newbie needs to engage in further discussion. It is not an end all, be all, final word, advocating the DSB.
I see your point. I will change the text from requiring oxygen or depleted oxygen to "live" to simply "function". That will better represent the facts I think.
Both exist simultaneously in the tank. It is pH dependant. We have
NH<sub>3</sub> + H<sub>2</sub>O ↔ NH<sub>4</sub> + OH<sup>-</sup> as the general equation. As pH rises the equilibrium shifts toward the NH<sub>3</sub> and that increases toxicity of of ammonia over ammonium.
both are present in the tank but at pH 8.3 ammonia represent about 10% of the total ammonium ion present. In a FW tank. at pH 7 it is less than 1%.
Both play a role in tank toxicity with NH<sub>3</sub> being the true worry toxic compound.
NH<sub>3</sub> + H<sub>2</sub>O ↔ NH<sub>4</sub> + OH<sup>-</sup> as the general equation. As pH rises the equilibrium shifts toward the NH<sub>3</sub> and that increases toxicity of of ammonia over ammonium.
both are present in the tank but at pH 8.3 ammonia represent about 10% of the total ammonium ion present. In a FW tank. at pH 7 it is less than 1%.
Both play a role in tank toxicity with NH<sub>3</sub> being the true worry toxic compound.
Nope, that is the one we wish to avoid but the tank's chemistry dictates that ammonium will convert to ammonia, the cause of toxicity. That is why we "cycle" a tank. If we have enough bacteria to handle the ammonia load and oxidize it to nitrite/nitrate then the tank become stable and less toxic to fish.
The whole concept of a DSB centers around the fact that nitrate, not especially toxic to fish, can reek havoc on corals. Denitrification in the bed makes nitrate into harmless nitrogen gas,
The whole concept of a DSB centers around the fact that nitrate, not especially toxic to fish, can reek havoc on corals. Denitrification in the bed makes nitrate into harmless nitrogen gas,
Aquarist007
New member
<a href=showthread.php?s=&postid=15128855#post15128855 target=_blank>Originally posted</a> by Whys
I swear you're all trying to drive me nuts, but you're too late for that!
Only one is going to appear on the diagram. Please vote for either... Ammonia (NH3) or... Ammonium (NH4). End of story.
Thanks.
I can't vote yet---its taking alot of pia matter just to understand all this great stuff
Well, truthfully, I vote for both as the two ionic species are present.
That is what happens Ryan when you post in Advanced topics.
That is what happens Ryan when you post in Advanced topics.
Aquarist007
New member
<a href=showthread.php?s=&postid=15128906#post15128906 target=_blank>Originally posted</a> by WaterKeeper
Well, truthfully, I vote for both as the two ionic species are present.
That is what happens Ryan when you post in Advanced topics.
:eek2: you would have to mention that Tom---it was I that suggested the thread be posted here to attract more experineced oppinions and discussions--I don't think Whys has let me off the hook for that yet:eek2:
When you pull me out of my league, on the Advanced Topic forum, I tend to give somewhat feeble answers, knowing I wall be seriously rebuked.
Whys
New member
Well then I guess the newbies will get to decide. I intend to run this by all of them for final approval. I suspect they'll vote for ammonia. But more importantly, I suspect they'll vote, as opposed to rambling on indefinitely.
FWIW, my salifert test kit says Ammonia. On the other hand, it also says NH4. Go figure...
I will attempt to rewrite the text to give recognition to the heavily weighted biological role of the bacteria.
Capn, I still like you and blame you for nothing. I just find the Advanced Topics forum to be another kind of Lounge. I naively believed that a DSB consensus was just a matter of reconciling the concepts and terminology.
When I'm in serious mode, I call them as I see them, tho am not 100% accurate. When it comes to debate and lively discussion, I come from a rough neighborhood and rarely take prisoners. I can turn that on myself and admit to being an uptight hyper-defensive a**. Can the rest of you admit to being obtuse? It would be easier to extract a tooth than a definitive answer, or even a simple vote, from the "high minded" intellectuals haunting this forum.
I do appreciate some of the input and believe it has improved the diagram. But each of you clearly has their own pet agenda that seems to ignore my stated objectives. You are each welcome to have your chemistry discussions and philosophical theory regarding sand bed depth, but I will state this one final time before posting the second draft, to be introduced to the newbie forum for final approval. THIS IS FOR NEWBIES! It is they who will have the final say.
Add what you can while the door is still open, because this train is leaving the station.
I thank each of you again for your input. My annoyance is not a measure of your contributions worth.
Worry not Capn, I'll have this bug out of myself soon enough and will gladly return to my usual habits.
FWIW, my salifert test kit says Ammonia. On the other hand, it also says NH4. Go figure...
I will attempt to rewrite the text to give recognition to the heavily weighted biological role of the bacteria.
Capn, I still like you and blame you for nothing. I just find the Advanced Topics forum to be another kind of Lounge. I naively believed that a DSB consensus was just a matter of reconciling the concepts and terminology.
When I'm in serious mode, I call them as I see them, tho am not 100% accurate. When it comes to debate and lively discussion, I come from a rough neighborhood and rarely take prisoners. I can turn that on myself and admit to being an uptight hyper-defensive a**. Can the rest of you admit to being obtuse? It would be easier to extract a tooth than a definitive answer, or even a simple vote, from the "high minded" intellectuals haunting this forum.
I do appreciate some of the input and believe it has improved the diagram. But each of you clearly has their own pet agenda that seems to ignore my stated objectives. You are each welcome to have your chemistry discussions and philosophical theory regarding sand bed depth, but I will state this one final time before posting the second draft, to be introduced to the newbie forum for final approval. THIS IS FOR NEWBIES! It is they who will have the final say.
Add what you can while the door is still open, because this train is leaving the station.
I thank each of you again for your input. My annoyance is not a measure of your contributions worth.
Worry not Capn, I'll have this bug out of myself soon enough and will gladly return to my usual habits.
Aquarist007
New member
well at least you don't get called names
actually I do understand your ideas very well==I guess I have strayed to far from home too--back to the newbie forum for me too
jenglish
Marquis de Carabas
<a href=showthread.php?s=&postid=15055405#post15055405 target=_blank>Originally posted</a> by jenglish
Seeking consensus on anything DSB related is like trying to decide pizza toppings between 4 people.... NOT GONNA HAPPEN
See, I wasn't being obtuse, just managing expectations for the process. :lol: Even in a pretty positivist area like chemistry there is debate on how to interpret data, such is the nature of pointy headed science guys
As far as ammonia vs. ammonium both would be more correct but if it's going to be one I would say ammonia, as it will be more recognized by Newbs. Unless we get into what was discussed in the new nitrate theory thread which was about bacteria processing nitrate back to ammonia and I would think that discussion, even if it had come to a consensus would be to complex a diagram to start out on. my .02
Been busy with playing with my aquariums. Can't wait for a discussion with Tom/Waterkeeper,glad he chimed in.
But first Ammonia/ Ammonium. I only pointed it out so it could be understood that the ammonium per se is not very toxic and it is represented as such in the chart ;the ammonia is and that both are often considered the same thing since they interchange instantaneously related to ph. I think it's important to understand things before attempting a teaching aide. I am focused.
They are often referred to as total ammonia and both are measured as one when you use a test kit. By far the most prevalent form in our tanks is ammonium,the more benign form. At ph 8.2 93% of the total ammonia present is ammonium .At ph 8.6,free ammonia (NH4) rises to 15% of the total. At ph 9.3, it's 50/50 ammonia/ammonium.I would represent them as Ammonia(NH3/4) .
But first Ammonia/ Ammonium. I only pointed it out so it could be understood that the ammonium per se is not very toxic and it is represented as such in the chart ;the ammonia is and that both are often considered the same thing since they interchange instantaneously related to ph. I think it's important to understand things before attempting a teaching aide. I am focused.
They are often referred to as total ammonia and both are measured as one when you use a test kit. By far the most prevalent form in our tanks is ammonium,the more benign form. At ph 8.2 93% of the total ammonia present is ammonium .At ph 8.6,free ammonia (NH4) rises to 15% of the total. At ph 9.3, it's 50/50 ammonia/ammonium.I would represent them as Ammonia(NH3/4) .
<a href=showthread.php?s=&postid=15130822#post15130822 target=_blank>Originally posted</a> by jenglish
See, I wasn't being obtuse, just managing expectations for the process. :lol: Even in a pretty positivist area like chemistry there is debate on how to interpret data, such is the nature of pointy headed science guys
As far as ammonia vs. ammonium both would be more correct but if it's going to be one I would say ammonia, as it will be more recognized by Newbs. Unless we get into what was discussed in the new nitrate theory thread which was about bacteria processing nitrate back to ammonia and I would think that discussion, even if it had come to a consensus would be to complex a diagram to start out on. my .02
Who's got a pointy head my undergraduate degree is a bachelor of arts.Besides my head is round and shiny here and there.:lol: :lol:Similar threads
