How exactly does live sand work? i understand how live rock work (the rock contains lots of microorganisms that basicly acts like a bio-filter) because water is constantly moving in and out and around them at all times. But in a live sand bed....there is sand on the surface which get the same treatment as the live rock, and there is sand BELOW that. How is the sand below recieving "fresh" water, foods, etc?
probably the dumbest question ever....
- Thread starter mrfish
- Start date
Nitrification/Denitrification 101
Nitrogen processing is performed by different species of bacteria, each responsible for particular conversions. A few genus (e.g. Nitrobacter, Nitrosoma, etc.) have been identified (NB initially isolated and identified for freshwater); countless others have not.
Nitrogenous waste (given off by decaying matter, fecal excrements, etc.) eventually form ammonia (NH4). The process of oxidizing nitrogen from ammonia (NH4) to nitrite (NO2) to nitrate (NO3) is called nitrification, and, like any oxiditive process, requires oxygen. Because nitrification is an aerobic process, it occurs near the surface of substrates (rock or sandbed), where the exposed areas are oxygen rich.
As you go deeper in the substrate, oxygen becomes more scarce. At a given threshold, oxygen becomes depleted from the immediate environment, and the environment is termed anoxic (void of oxygen). In these anoxic areas, a seperate process occurs, called denitrification. Denitrification, unlike nitrification, is an anaerobic process (without oxygen). The process of dentrification can be performed by various bacterial species, and most commonly results in the formation of nitrogen gases N & N2, or nitrous oxide (NO).
Interesting tidbits:
1. Nitrification and denitrification are two independent processes.
2. Nitrication is part of the nitrogen cycle. The nitrogen cycle is the pathways for which nitrogen travels (recycled) without a given environment. Dentrification is not part of the nitrogen cycle.
3. Denitrification is the process of removing nitrogen from the immediate environment, and does not necessarily mean nitrate reduction.
4. Denitrifiation requires a molybdenum-based enzyme to serve as a catalyst for the conversion process. I postulate that for this reason alone, aragonite sandbeds (which contain molybdenum) are very valuable sources for dentrification.
Back to the topic ...
As orgnanic matter decays, nitrogen is released back into the water as dissolved nitrogen. Because of osmotic gradients, this water slowly seeps down into the deepest of substrates, where it is processed in the journey downwards. As stated, it is nitrified at the top strata where oxygen is present, and as nitrification's byproducts (namely nitrate) slowly works their way further down, they are denitrified in the anoxic stratas.
A completely closed biome that is purely aerobic, with nitrogenous inputs (mostly from feedings) will result in high levels of nitrate (the end product of nitrication). As we all know, high nitrate levels can be toxic to invertebrates. So we look for ways to alleviate NO3 buildup.
Methods of reducing nitrate buildup:
1. Water volume exchange. This dilutes the nutrient levels in our tank.
2. Reduce nitrogen input. This primarily means reduced feeding.
3. Removal of nitrogenous products from the water column via chemical filtration. Protein skimming, granular activiated carbon, and ozone are examples.
4. Denitrification. This is by far the easiest, most complete, and least stressful of the methods.
Now, nitrification is easy to accomplish: throw in oxygen, nitrogenous waste, and water, and it'll happen. As previously mentioned, what ends up is a buildup of it's end-product, nitrate. Denitrification, however, is much trickier because the process is obligatory anaerobic. Therefore, we do not want all the available surface area to be aerobic, or otherwise wet/dry's would suffice. What we're striving for in our closed reefs is a balance of nitrification and denitrification. Better put, we're looking for the balance of aerobic, nitrifying bacteria populations, and anaerobic, denitrying bacteria populations. Rocks and shallow sand beds accomplish the former. Dense rock and deep sand beds accomplish the latter.
Nitrogen processing is performed by different species of bacteria, each responsible for particular conversions. A few genus (e.g. Nitrobacter, Nitrosoma, etc.) have been identified (NB initially isolated and identified for freshwater); countless others have not.
Nitrogenous waste (given off by decaying matter, fecal excrements, etc.) eventually form ammonia (NH4). The process of oxidizing nitrogen from ammonia (NH4) to nitrite (NO2) to nitrate (NO3) is called nitrification, and, like any oxiditive process, requires oxygen. Because nitrification is an aerobic process, it occurs near the surface of substrates (rock or sandbed), where the exposed areas are oxygen rich.
As you go deeper in the substrate, oxygen becomes more scarce. At a given threshold, oxygen becomes depleted from the immediate environment, and the environment is termed anoxic (void of oxygen). In these anoxic areas, a seperate process occurs, called denitrification. Denitrification, unlike nitrification, is an anaerobic process (without oxygen). The process of dentrification can be performed by various bacterial species, and most commonly results in the formation of nitrogen gases N & N2, or nitrous oxide (NO).
Interesting tidbits:
1. Nitrification and denitrification are two independent processes.
2. Nitrication is part of the nitrogen cycle. The nitrogen cycle is the pathways for which nitrogen travels (recycled) without a given environment. Dentrification is not part of the nitrogen cycle.
3. Denitrification is the process of removing nitrogen from the immediate environment, and does not necessarily mean nitrate reduction.
4. Denitrifiation requires a molybdenum-based enzyme to serve as a catalyst for the conversion process. I postulate that for this reason alone, aragonite sandbeds (which contain molybdenum) are very valuable sources for dentrification.
Back to the topic ...
As orgnanic matter decays, nitrogen is released back into the water as dissolved nitrogen. Because of osmotic gradients, this water slowly seeps down into the deepest of substrates, where it is processed in the journey downwards. As stated, it is nitrified at the top strata where oxygen is present, and as nitrification's byproducts (namely nitrate) slowly works their way further down, they are denitrified in the anoxic stratas.
A completely closed biome that is purely aerobic, with nitrogenous inputs (mostly from feedings) will result in high levels of nitrate (the end product of nitrication). As we all know, high nitrate levels can be toxic to invertebrates. So we look for ways to alleviate NO3 buildup.
Methods of reducing nitrate buildup:
1. Water volume exchange. This dilutes the nutrient levels in our tank.
2. Reduce nitrogen input. This primarily means reduced feeding.
3. Removal of nitrogenous products from the water column via chemical filtration. Protein skimming, granular activiated carbon, and ozone are examples.
4. Denitrification. This is by far the easiest, most complete, and least stressful of the methods.
Now, nitrification is easy to accomplish: throw in oxygen, nitrogenous waste, and water, and it'll happen. As previously mentioned, what ends up is a buildup of it's end-product, nitrate. Denitrification, however, is much trickier because the process is obligatory anaerobic. Therefore, we do not want all the available surface area to be aerobic, or otherwise wet/dry's would suffice. What we're striving for in our closed reefs is a balance of nitrification and denitrification. Better put, we're looking for the balance of aerobic, nitrifying bacteria populations, and anaerobic, denitrying bacteria populations. Rocks and shallow sand beds accomplish the former. Dense rock and deep sand beds accomplish the latter.
<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by Leonard:
<STRONG>Nitrification/Denitrification 101
Nitrogen processing is performed by different species of bacteria, each responsible for particular conversions. A few genus (e.g. Nitrobacter, Nitrosoma, etc.) have been identified (NB initially isolated and identified for freshwater); countless others have not.
Nitrogenous waste (given off by decaying matter, fecal excrements, etc.) eventually form ammonia (NH4). The process of oxidizing nitrogen from ammonia (NH4) to nitrite (NO2) to nitrate (NO3) is called nitrification, and, like any oxiditive process, requires oxygen. Because nitrification is an aerobic process, it occurs near the surface of substrates (rock or sandbed), where the exposed areas are oxygen rich.
As you go deeper in the substrate, oxygen becomes more scarce. At a given threshold, oxygen becomes depleted from the immediate environment, and the environment is termed anoxic (void of oxygen). In these anoxic areas, a seperate process occurs, called denitrification. Denitrification, unlike nitrification, is an anaerobic process (without oxygen). The process of dentrification can be performed by various bacterial species, and most commonly results in the formation of nitrogen gases N & N2, or nitrous oxide (NO).
Interesting tidbits:
1. Nitrification and denitrification are two independent processes.
2. Nitrication is part of the nitrogen cycle. The nitrogen cycle is the pathways for which nitrogen travels (recycled) without a given environment. Dentrification is not part of the nitrogen cycle.
3. Denitrification is the process of removing nitrogen from the immediate environment, and does not necessarily mean nitrate reduction.
4. Denitrifiation requires a molybdenum-based enzyme to serve as a catalyst for the conversion process. I postulate that for this reason alone, aragonite sandbeds (which contain molybdenum) are very valuable sources for dentrification.
Back to the topic ...
As orgnanic matter decays, nitrogen is released back into the water as dissolved nitrogen. Because of osmotic gradients, this water slowly seeps down into the deepest of substrates, where it is processed in the journey downwards. As stated, it is nitrified at the top strata where oxygen is present, and as nitrification's byproducts (namely nitrate) slowly works their way further down, they are denitrified in the anoxic stratas.
A completely closed biome that is purely aerobic, with nitrogenous inputs (mostly from feedings) will result in high levels of nitrate (the end product of nitrication). As we all know, high nitrate levels can be toxic to invertebrates. So we look for ways to alleviate NO3 buildup.
Methods of reducing nitrate buildup:
1. Water volume exchange. This dilutes the nutrient levels in our tank.
2. Reduce nitrogen input. This primarily means reduced feeding.
3. Removal of nitrogenous products from the water column via chemical filtration. Protein skimming, granular activiated carbon, and ozone are examples.
4. Denitrification. This is by far the easiest, most complete, and least stressful of the methods.
Now, nitrification is easy to accomplish: throw in oxygen, nitrogenous waste, and water, and it'll happen. As previously mentioned, what ends up is a buildup of it's end-product, nitrate. Denitrification, however, is much trickier because the process is obligatory anaerobic. Therefore, we do not want all the available surface area to be aerobic, or otherwise wet/dry's would suffice. What we're striving for in our closed reefs is a balance of nitrification and denitrification. Better put, we're looking for the balance of aerobic, nitrifying bacteria populations, and anaerobic, denitrying bacteria populations. Rocks and shallow sand beds accomplish the former. Dense rock and deep sand beds accomplish the latter.</STRONG><HR></BLOCKQUOTE>
WE know who has a Ph.D
<STRONG>Nitrification/Denitrification 101
Nitrogen processing is performed by different species of bacteria, each responsible for particular conversions. A few genus (e.g. Nitrobacter, Nitrosoma, etc.) have been identified (NB initially isolated and identified for freshwater); countless others have not.
Nitrogenous waste (given off by decaying matter, fecal excrements, etc.) eventually form ammonia (NH4). The process of oxidizing nitrogen from ammonia (NH4) to nitrite (NO2) to nitrate (NO3) is called nitrification, and, like any oxiditive process, requires oxygen. Because nitrification is an aerobic process, it occurs near the surface of substrates (rock or sandbed), where the exposed areas are oxygen rich.
As you go deeper in the substrate, oxygen becomes more scarce. At a given threshold, oxygen becomes depleted from the immediate environment, and the environment is termed anoxic (void of oxygen). In these anoxic areas, a seperate process occurs, called denitrification. Denitrification, unlike nitrification, is an anaerobic process (without oxygen). The process of dentrification can be performed by various bacterial species, and most commonly results in the formation of nitrogen gases N & N2, or nitrous oxide (NO).
Interesting tidbits:
1. Nitrification and denitrification are two independent processes.
2. Nitrication is part of the nitrogen cycle. The nitrogen cycle is the pathways for which nitrogen travels (recycled) without a given environment. Dentrification is not part of the nitrogen cycle.
3. Denitrification is the process of removing nitrogen from the immediate environment, and does not necessarily mean nitrate reduction.
4. Denitrifiation requires a molybdenum-based enzyme to serve as a catalyst for the conversion process. I postulate that for this reason alone, aragonite sandbeds (which contain molybdenum) are very valuable sources for dentrification.
Back to the topic ...
As orgnanic matter decays, nitrogen is released back into the water as dissolved nitrogen. Because of osmotic gradients, this water slowly seeps down into the deepest of substrates, where it is processed in the journey downwards. As stated, it is nitrified at the top strata where oxygen is present, and as nitrification's byproducts (namely nitrate) slowly works their way further down, they are denitrified in the anoxic stratas.
A completely closed biome that is purely aerobic, with nitrogenous inputs (mostly from feedings) will result in high levels of nitrate (the end product of nitrication). As we all know, high nitrate levels can be toxic to invertebrates. So we look for ways to alleviate NO3 buildup.
Methods of reducing nitrate buildup:
1. Water volume exchange. This dilutes the nutrient levels in our tank.
2. Reduce nitrogen input. This primarily means reduced feeding.
3. Removal of nitrogenous products from the water column via chemical filtration. Protein skimming, granular activiated carbon, and ozone are examples.
4. Denitrification. This is by far the easiest, most complete, and least stressful of the methods.
Now, nitrification is easy to accomplish: throw in oxygen, nitrogenous waste, and water, and it'll happen. As previously mentioned, what ends up is a buildup of it's end-product, nitrate. Denitrification, however, is much trickier because the process is obligatory anaerobic. Therefore, we do not want all the available surface area to be aerobic, or otherwise wet/dry's would suffice. What we're striving for in our closed reefs is a balance of nitrification and denitrification. Better put, we're looking for the balance of aerobic, nitrifying bacteria populations, and anaerobic, denitrying bacteria populations. Rocks and shallow sand beds accomplish the former. Dense rock and deep sand beds accomplish the latter.</STRONG><HR></BLOCKQUOTE>
WE know who has a Ph.D
mrfish, in short live sand is very similar to live rock, different bacteria also lives in the sand. It may appear compacted to our eyes but in reality there is enough surface area for bacteria to live in. Worms and other animals also will bury in the sand and create tunnels and paths. The deep layer in the sand is where there will be a lack/low amount of oxygen. Anaerobic bacteria will colonize here and help break down mainly the nitrates that accumilate in our tanks. So this is where you will find many threads and posts about DSB, how deep, and such.
This is my view on it and the way I would explain it.
Hope this helps a bit.
This is my view on it and the way I would explain it.
Hope this helps a bit.
Ok...I'll take a shot at this.
Your surface sand does get the same bacteria as your live rock, and acts in a similar manner. This sand also has lots of little critters that process detrius, and stir the sand up so that some water is moved down into the lower levels of the sand. In the lower sand levels, oxygen has already been depleted from the water. There, anerobic bacteria slowly breaks down you nitrates into nitrogen, and really finishes the nitrogen cycle. It's the anerobic area that makes the difference between filtration in the rock, and in the sandbed. This only really applies if you're using a deep sand bed, so that's why it's important to get a few inches in your tank.
Hope that helps (and is correct).
Your surface sand does get the same bacteria as your live rock, and acts in a similar manner. This sand also has lots of little critters that process detrius, and stir the sand up so that some water is moved down into the lower levels of the sand. In the lower sand levels, oxygen has already been depleted from the water. There, anerobic bacteria slowly breaks down you nitrates into nitrogen, and really finishes the nitrogen cycle. It's the anerobic area that makes the difference between filtration in the rock, and in the sandbed. This only really applies if you're using a deep sand bed, so that's why it's important to get a few inches in your tank.
Hope that helps (and is correct).
<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by mrfish:
<STRONG>How exactly does live sand work? i understand how live rock work (the rock contains lots of microorganisms that basicly acts like a bio-filter) because water is constantly moving in and out and around them at all times. But in a live sand bed....there is sand on the surface which get the same treatment as the live rock, and there is sand BELOW that. How is the sand below recieving "fresh" water, foods, etc?</STRONG><HR></BLOCKQUOTE>
To address your question more specifically, we dont' water to be "constantly moving in and out." We need to impede water flow to produce the anoxic environments required for denitrification. Deep sand beds are perfect for impeding the flow of oxygenated water. NB water doesn't stop at the surface of sandbeds. Sandbeds are very permeable, and water (rich is dissolved nitrogen [ie "food]) will work its way down slowly. And this is what we want. How fast it works it's way down, and how effective it is at denitrifying is highly dependant on grain size.
<STRONG>How exactly does live sand work? i understand how live rock work (the rock contains lots of microorganisms that basicly acts like a bio-filter) because water is constantly moving in and out and around them at all times. But in a live sand bed....there is sand on the surface which get the same treatment as the live rock, and there is sand BELOW that. How is the sand below recieving "fresh" water, foods, etc?</STRONG><HR></BLOCKQUOTE>
To address your question more specifically, we dont' water to be "constantly moving in and out." We need to impede water flow to produce the anoxic environments required for denitrification. Deep sand beds are perfect for impeding the flow of oxygenated water. NB water doesn't stop at the surface of sandbeds. Sandbeds are very permeable, and water (rich is dissolved nitrogen [ie "food]) will work its way down slowly. And this is what we want. How fast it works it's way down, and how effective it is at denitrifying is highly dependant on grain size.
Leonard -- One part of your 101 explanation really grabbed my undivided attention:
"Because of osmotic gradients, this water slowly seeps down into the deepest of substrates, where it is processed in the journey downwards."
This statement references a denitrification model that treats surface tension of the wetted particles of the substrate in the anoxic region as a boundary-layer membrane exposed to osmotic pressure. (Osmotic gradients are those that exit across a semi-permeable membrane, just like inside an RO unit.)
You obviously researched this topic very recently. I think I remember seeing this approach suggested somewhere in the literature sometime years back, but I can't recall where, and I have never heard of anyone having followed it all the way out. The transport phenomena numerical analysis required for this gets absolutely wild, even for a computer!
(The classical approach postulates that chemical diffusion driven by concentration gradients is the primary transport phenomena in denitrification and treats bulk motion of the water as being negligible, thus avoiding the problem.)
Do you remember who did this work or where you read about it? How closely do the results of this model agree or disagree with the old model? Do you recall what particle size distribution they assumed for their model? Uniform? Linear? Gaussian? Geez -- just when I thought I half-way had a handle on this stuff, somebody does something really new! I guess computers really are getting faster, and apparently, I'm NOT...!
[ July 20, 2001: Message edited by: BReefCase ]
"Because of osmotic gradients, this water slowly seeps down into the deepest of substrates, where it is processed in the journey downwards."
This statement references a denitrification model that treats surface tension of the wetted particles of the substrate in the anoxic region as a boundary-layer membrane exposed to osmotic pressure. (Osmotic gradients are those that exit across a semi-permeable membrane, just like inside an RO unit.)
You obviously researched this topic very recently. I think I remember seeing this approach suggested somewhere in the literature sometime years back, but I can't recall where, and I have never heard of anyone having followed it all the way out. The transport phenomena numerical analysis required for this gets absolutely wild, even for a computer!
(The classical approach postulates that chemical diffusion driven by concentration gradients is the primary transport phenomena in denitrification and treats bulk motion of the water as being negligible, thus avoiding the problem.)
Do you remember who did this work or where you read about it? How closely do the results of this model agree or disagree with the old model? Do you recall what particle size distribution they assumed for their model? Uniform? Linear? Gaussian? Geez -- just when I thought I half-way had a handle on this stuff, somebody does something really new! I guess computers really are getting faster, and apparently, I'm NOT...!
[ July 20, 2001: Message edited by: BReefCase ]
I can't recall. To be honest, I didn't extensively research the topic for this thread, and the last I remember reading about this topic in any depth was more then 3 months ago. It's my (cloudy) recollection that the particular information I put forth may have been derived from either NSF or EPA studies (or some other government funded/subsidized org.). I will see if I can't find the source by next week's end. Hopefully, I wasn't citing plant/root denitrification processes (I'm pretty sure I wasn't).
I wrote my response in about 10 minutes time, without much formulation (hence, the chaotic structure of my response). It's amazing what I recall in "stream-of-thought" writing. The human brain is an amazing thing. Amazing, but at the same time, strange ... I'm not quite sure why I didn't cite diffusion as the mechansim; it is indeed the classical model (one that is popularized even in reef aquarium literature), and the safer (ie simplier) theory to suppose. Perhaps it was fresher/more intriguing in my mind?
If you have any information or ideas, I'd greatly appreciate it if you could clue me in. My mind is admittedly not in tip-top form due to workplace stresses. If my initial information was improperly applied in this situation, I apologize in advance. I hate getting people excited about things
BTW, computers are getting EXTREMELY fast. My CS buddy mentioned reaching silicon's inherent threshold within the next 2 decades. Organic-based technology - now that's exciting!
[ July 20, 2001: Message edited by: Leonard ]
I wrote my response in about 10 minutes time, without much formulation (hence, the chaotic structure of my response). It's amazing what I recall in "stream-of-thought" writing. The human brain is an amazing thing. Amazing, but at the same time, strange ... I'm not quite sure why I didn't cite diffusion as the mechansim; it is indeed the classical model (one that is popularized even in reef aquarium literature), and the safer (ie simplier) theory to suppose. Perhaps it was fresher/more intriguing in my mind?
If you have any information or ideas, I'd greatly appreciate it if you could clue me in. My mind is admittedly not in tip-top form due to workplace stresses. If my initial information was improperly applied in this situation, I apologize in advance. I hate getting people excited about things
BTW, computers are getting EXTREMELY fast. My CS buddy mentioned reaching silicon's inherent threshold within the next 2 decades. Organic-based technology - now that's exciting!
[ July 20, 2001: Message edited by: Leonard ]
mrfish
I'd go with 90-95% "dead" sand, and innoculate the remaining portion with quality live sand. In a few months, your entire bed will teem with life as if it were all live sand. There's nothing wrong with utilizing all live sand; it's just very cost prohibitive (and wasteful, IMO).
Concerning the specifics about recommended particulate size, I suggest you ask Dr. Ron (URL below). For denitrification, it doesn't really matter if grains are uniform or not, so long as they under 1mm (average). But that completely ignores the biological issues, which Ron can better answer. He can propose a good blend of substrate to achieve the highest species habitation and diversification.
http://www.reefcentral.com/vbulletin/forumdisplay.php?s=&forumid=40
I'd go with 90-95% "dead" sand, and innoculate the remaining portion with quality live sand. In a few months, your entire bed will teem with life as if it were all live sand. There's nothing wrong with utilizing all live sand; it's just very cost prohibitive (and wasteful, IMO).
Concerning the specifics about recommended particulate size, I suggest you ask Dr. Ron (URL below). For denitrification, it doesn't really matter if grains are uniform or not, so long as they under 1mm (average). But that completely ignores the biological issues, which Ron can better answer. He can propose a good blend of substrate to achieve the highest species habitation and diversification.
http://www.reefcentral.com/vbulletin/forumdisplay.php?s=&forumid=40
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