Are Deep Sand Beds, DSBs, dangerous to use in a marine aquarium?
- Thread starter JPMagyar
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Clown Tang
New member
You're the one that is confused now. If you don't understand what a scientific theory is, then I can't even deal with anything else you've stated. When something in science is a theory, that means there is huge amount of evidence to prove that it is real. For example, the theory of gravity. Evolution is fact, that's why it is a scientific theory. Not a theory in the sense of "my theory is this..." That's a hypothesis. A hypothesis that is supported by HUGE amounts of evidence becomes a theory. And as far as evolution goes, there is NO evidence against it. Only HUGE amounts of evidence FOR it.
Everything I stated in my original response is a fact. Sand beds absorb wastes as the life within the beds slowly decompose it. Fact. As this waste decomposes, toxic gases can build up. Fact.
Everything I stated in my original response is a fact.
Well not everything.
For example not much fact here vs opinion:
As this layer gets deeper and deeper over time (as more material is pushed down on top of it), the layer will eventually enter anaerobic zones if the bed is deep enough for that. Once here, it will continue to be broken down by anaerobic bacteria that release hydrogen sulfide as a byproduct of the denitrification process.
Anaerobic activity can occur in shallow areas ,the bed doesn't have to be "deep enough" for them to exist.
I don't think you can say organaic material adsorbs to substrate. Some organics may settle there and degradation may occur as wel as colonization by some organisms there I'm skeptical adsorbtion is the mechanism involved .
Organics degrade over time ,so the layer doesn't necessarily just keep growing; some of it becomes refractory and basically inert. Some of teh byproducts of degradtion move out to the water column.
Hydrogen sulfide is not a by product of denitrification. It's a by product of sulfate reduction which occurs when there is organic carbon available and no oxygen or nitrate,in anoxic conditions.
None of it has anything to do with tobacco.
Well not everything.
For example not much fact here vs opinion:
As this layer gets deeper and deeper over time (as more material is pushed down on top of it), the layer will eventually enter anaerobic zones if the bed is deep enough for that. Once here, it will continue to be broken down by anaerobic bacteria that release hydrogen sulfide as a byproduct of the denitrification process.
Anaerobic activity can occur in shallow areas ,the bed doesn't have to be "deep enough" for them to exist.
I don't think you can say organaic material adsorbs to substrate. Some organics may settle there and degradation may occur as wel as colonization by some organisms there I'm skeptical adsorbtion is the mechanism involved .
Organics degrade over time ,so the layer doesn't necessarily just keep growing; some of it becomes refractory and basically inert. Some of teh byproducts of degradtion move out to the water column.
Hydrogen sulfide is not a by product of denitrification. It's a by product of sulfate reduction which occurs when there is organic carbon available and no oxygen or nitrate,in anoxic conditions.
None of it has anything to do with tobacco.
You realize that you quoted me stating that evolution is a theory and then proceeded to tell me that I am confused and that I do not understand only to write that evolution is a theory.
I guess I really am confused now because by that logic you are telling everyone that you are confused as well (and that is ok) or if you state that you are not confused then I must not be confused either since we both typed that evolution is a theory. Which path should we go down together?
I am sorry that you are finding it difficult to deal with anything else I stated and I hope that I did not cause too much stress and frustration but you really should relax more.
Because you were nice enough to tell me about science I thought that I would tell you my definitions of fact and theory regarding science.
Scientific facts have been confirmed through repeated observations and experiments and are generally accepted as true. The issue with facts is that over time they may be altered or abandoned completely due to new research.
Scientific theories use these facts and other components (e.g., tested hypotheses) to explain a phenomenon of a system.
Darwin took numerous facts and his own observations to propose a conceptual or theoretical framework to explain this aspect of nature. This has held up nicely hasn't it? As you stated, the amount of evidence to support it is overwhelming.
Regarding evolution it could be debated that it should be considered as both scientific fact and scientific theory or even as just fact. However for me I have and will continue to use the term theory and not fact when discussing this subject. I may change my mind one day though.
Why?
1. Theories make predictions of unobserved events. Example: the fossil record.
2. The facts are there but this framework is still being refined and the theory may still um, evolve. Example: the rate of evolution.
This last one is probably the hardest but in reality it should be the easiest. If you support the scientific method then by that point this should be once again called a theory.
3. With the advancement of technology and the rate at which information is gained, one should entertain the idea that a new theory may be presented one day that may alter or force us to abandon completely Darwin's theory of evolution.
Just look at what happened to Newton's theory of gravitation when Einstein did some math in his head and on paper for a few years. Sure it took more than 200 years but facts are......
hbrochs
New member
I have a three inch sand bed because I like the way it looks, my fish like it, and I believe its a place for bacteria to process waste.
I think detritus and other noxious stuff builds up in there over time.
I vacuum the whole top of the sand bed lightly every water change, and I vacuum small sections deeply. I've only been doing this seven months, but its working so far.
I think detritus and other noxious stuff builds up in there over time.
I vacuum the whole top of the sand bed lightly every water change, and I vacuum small sections deeply. I've only been doing this seven months, but its working so far.
CStrickland
New member
Hi Dave. You might like this thread, http://reefcentral.com/forums/showthread.php?t=595109 it's pretty long too but they explore a lot of the ideas you are pondering. You can also search for info about Remote Deep Sand Beds (RDSB). It seems like a lot of people have success with them, or at least they post more lol. I was thinking about trying something like that while I was planning, but I decided I would add stuff as needed and I haven't had nutrient issues (yet, *knocks wood*) so just cleaning the rocks and sand out is working for now. Happy researching!
ETA: oh wow, I missed a whole page there! You guys have been busier than my notifications could keep up with I guess, lol. Oh well, I'll just leave this here anyway
CStrickland
New member
Lol@ things Paul'd rather have:
Old beer cans
Nasty rugf plates
An actual hammer
Leeks
Nitrates
Preggo fish
MRSA
Merlot
Old beer cans
Nasty rugf plates
An actual hammer
Leeks
Nitrates
Preggo fish
MRSA
Merlot
Reefin' Dude
New member
Sorry, i do not mean to be misrepresenting. I think there is a lot of overgeneralization going on. It is a two way street, but in order to have this two way street there needs to be an imbalance. Diffusion deals with soluble compounds. Diffusion is not working on the solid material until the solid material has been broken down by bacteria and some of it becomes soluble.
The only way P is going to be encased in the matrix is if the matrix is being formed. This is going on in hermatypic organisms in our system. The skeleton/shell laid down can have encased P in it. This is not going on in the substrate or in the LR. The P is getting bound to any available sites on the outside of the matrix. It is just as available to bacteria as it was before. Depending on pH.
G~
IMO:
Some new crystal growth can also occur abiotically on new substrate. Some may also form on new abiotic precipitant that can occur when alk and calcium are high. The phosphate encased in the crystal matrix does not move not significantly anyway in any time frame we are concerned about unless the aragonite dissolves in acetic conditions. Thus , the phosphate encased in the crystals in the sand or elsewhere is of no significant consequence at normal reef tank pH.
Mostly, the phosphate added to the tank mostly via foods needs to be exported by harvested organisms like algae and bacteria , sunk in new crystal growth formed biotically or abiotically( the later is likely relatively minimal in a tank with calcifying organisms at normal range calcium, alkainity and magnesium )or taken out via sorbents or flocculants like GFO ,GAC or lanthanum chloride.
Equilibriation of surface bound PO4 species with the water does occur without dissolution as is evident when rock previously exposed to high PO4 leaches PO4 into water where PO4 is low even with high pH. It is also available for organisms including bacteria to use and evident in algae growth on new rock . This is not the same for PO4 encased in the matrix.Acess is more difficult and it can stay put for millenia.
Some new crystal growth can also occur abiotically on new substrate. Some may also form on new abiotic precipitant that can occur when alk and calcium are high. The phosphate encased in the crystal matrix does not move not significantly anyway in any time frame we are concerned about unless the aragonite dissolves in acetic conditions. Thus , the phosphate encased in the crystals in the sand or elsewhere is of no significant consequence at normal reef tank pH.
Mostly, the phosphate added to the tank mostly via foods needs to be exported by harvested organisms like algae and bacteria , sunk in new crystal growth formed biotically or abiotically( the later is likely relatively minimal in a tank with calcifying organisms at normal range calcium, alkainity and magnesium )or taken out via sorbents or flocculants like GFO ,GAC or lanthanum chloride.
Equilibriation of surface bound PO4 species with the water does occur without dissolution as is evident when rock previously exposed to high PO4 leaches PO4 into water where PO4 is low even with high pH. It is also available for organisms including bacteria to use and evident in algae growth on new rock . This is not the same for PO4 encased in the matrix.Acess is more difficult and it can stay put for millenia.
Reefin' Dude
New member
I think this is where we have the greatest difference of opinion. I agree with harvesting bacteria, i think the bigger the skimmer the better. The more water the skimmer can process the better.
I disagree about using algae, GFO, or GAC. These are inefficient ways of exporting organically bound P. Useful for soluble P. The bacteria (with the skimmer) in the water column will do this if the amount of available soluble P is kept under control by controlling the organically bound P. GFO, GAC, and elemental carbon dosing are all dependent on the creation of soluble P from the decomposition of organic matter by bacteria.
I think our biggest disagreement is with how organically bound P is dealt with by aquarist. I say get it out at a rate that maintains the desired nutrient state. Clean the litter box. Get it out before most of it has a chance to be taken up by other organisms or decomposed by bacteria. Creating more soluble P, N, and CO2. We are trying to limit these resources in our systems. I do not see the logic in keeping waste organic material around in order to create these resources. Then go about removing them or dealing with their effects.
G~
.I disagree about using algae, GFO, or GAC. These are inefficient ways of exporting organically bound P. Useful for soluble P.
GAC sorbs organics that hold phospahte and nitrogen mostly those that are hydrophobic . It does not adsorb inorganic phosphate as stated above.
GFO adsorbs some organic phosphate too as well as its more well known target , inorganic phosphate.
Skimming removes primarily ampipathic organics and some hydrophobic organics trapped in the air water interface between the bubbles as well as whatever else it happens to push along. The bacteria are ampipathic
I'm skeptical the hetertrophic bacteria encouraged by organic carbon dosing don't use some organic phosphate . It seems they do.
Many times GFO is used alongside organic carbon dosing to reduce PO4 as anaerobic denitrification can skew the organic carbon dosing effect toward a disproportionate nitrogen removal relative to inorganic phosphate removal.
I haven't used it or needed it to maintain PO4 at <0.04ppm and NO3 around 0.2ppm or less since Aug of 2013 but used it for many years before that.
GAC is helpful in removing primarily hydrophobic organics and it is asserted in some of the studies cited earlier in the thread that it does about twice as much of that than skimming does.
We've discussed all of the above before.
As for cleaning up( skimming , siphoning adsorbents,etc.) many argue you can over do it . Personally, I think overall it's a matter of balance in terms of cleaning and nutrient removal via exporting detritus. Overdoing nutrient removal can deprive organisms of nutrients they need for life functions. Deficiencies in nitrogen and phosphate et al do occur even in tanks with sand beds .These deficienciencies effect different orgnisms in differnent ways at variable thresholds for various elements. Xenia as one example do poorly in my heavily skimmed tanks vs my unskimmed tanks.
Personally , I frequently clean out detritus whether or not the tank has sand . My tanks are very clean by most standards.
Sand can be useful in segregating some the detritus from close contact with the coral . I don't worry about some detritus in the cryptic fuge or remote sand bed or in deep sand making it's way through the bacterial cascade though and suspect some of the organic and inorganic solutes released are actually helpful to the food web .
Sand can be useful in segregating some the detritus from close contact with coral Zoanthus in a well fed bare bottom tank for example can be easily swamped by acummulated detritus without very frequent siphoning .Some eggcrate or sand can help keep it off the coral,ime.
GAC sorbs organics that hold phospahte and nitrogen mostly those that are hydrophobic . It does not adsorb inorganic phosphate as stated above.
GFO adsorbs some organic phosphate too as well as its more well known target , inorganic phosphate.
Skimming removes primarily ampipathic organics and some hydrophobic organics trapped in the air water interface between the bubbles as well as whatever else it happens to push along. The bacteria are ampipathic
I'm skeptical the hetertrophic bacteria encouraged by organic carbon dosing don't use some organic phosphate . It seems they do.
Many times GFO is used alongside organic carbon dosing to reduce PO4 as anaerobic denitrification can skew the organic carbon dosing effect toward a disproportionate nitrogen removal relative to inorganic phosphate removal.
I haven't used it or needed it to maintain PO4 at <0.04ppm and NO3 around 0.2ppm or less since Aug of 2013 but used it for many years before that.
GAC is helpful in removing primarily hydrophobic organics and it is asserted in some of the studies cited earlier in the thread that it does about twice as much of that than skimming does.
We've discussed all of the above before.
As for cleaning up( skimming , siphoning adsorbents,etc.) many argue you can over do it . Personally, I think overall it's a matter of balance in terms of cleaning and nutrient removal via exporting detritus. Overdoing nutrient removal can deprive organisms of nutrients they need for life functions. Deficiencies in nitrogen and phosphate et al do occur even in tanks with sand beds .These deficienciencies effect different orgnisms in differnent ways at variable thresholds for various elements. Xenia as one example do poorly in my heavily skimmed tanks vs my unskimmed tanks.
Personally , I frequently clean out detritus whether or not the tank has sand . My tanks are very clean by most standards.
Sand can be useful in segregating some the detritus from close contact with the coral . I don't worry about some detritus in the cryptic fuge or remote sand bed or in deep sand making it's way through the bacterial cascade though and suspect some of the organic and inorganic solutes released are actually helpful to the food web .
Sand can be useful in segregating some the detritus from close contact with coral Zoanthus in a well fed bare bottom tank for example can be easily swamped by acummulated detritus without very frequent siphoning .Some eggcrate or sand can help keep it off the coral,ime.
adam.direct
New member
good/bad/ugly? IDK
My experience: had a 90gal reef for years with many different sump set ups. the final iteration had about an 80 gal sump. the display tank had a sand bed about 6" deep, while my sump and a large refuge with another 7-8" sand (no mud was used). the tank had tons of live rock and every spare space in the sump was packed with live rock. i tried filter socks for a while and really just got lazy, so i took out all the filtration and left only the live sand and live rock. the tank was rock solid. i ended up traveling a lot the last year i had it, and only did about 4 water changes in that year. the fish got a little skinny but everything looked great!. why do i bring all this up? was the success of my tank (with very little effort on my part) due to a mature tank with tons of live rock? possibly, was it facilitated by the DSB? I'd like to think so.
just my take on it, on my next build i will use a DSB
*note: i never disturbed the sand bed.
My experience: had a 90gal reef for years with many different sump set ups. the final iteration had about an 80 gal sump. the display tank had a sand bed about 6" deep, while my sump and a large refuge with another 7-8" sand (no mud was used). the tank had tons of live rock and every spare space in the sump was packed with live rock. i tried filter socks for a while and really just got lazy, so i took out all the filtration and left only the live sand and live rock. the tank was rock solid. i ended up traveling a lot the last year i had it, and only did about 4 water changes in that year. the fish got a little skinny but everything looked great!. why do i bring all this up? was the success of my tank (with very little effort on my part) due to a mature tank with tons of live rock? possibly, was it facilitated by the DSB? I'd like to think so.
just my take on it, on my next build i will use a DSB
*note: i never disturbed the sand bed.
A managed DSB system in the Netherlands, currently also tested on/for hobby sized systems, has been successful for many years in large (commercial) systems in keeping N and P in check. https://www.facebook.com/dymico/info?tab=page_info
In certain cases without additional P exports required and others where it was/is required. Nothing strange about that because in my old skimmer based reef setup I had to use GFO as well, where in my current skimmer based reef setup I don't have to use GFO. No system is the same and with the right maintenance a DSB can be a great addition where something like H2S won't ever be a problem.
In certain cases without additional P exports required and others where it was/is required. Nothing strange about that because in my old skimmer based reef setup I had to use GFO as well, where in my current skimmer based reef setup I don't have to use GFO. No system is the same and with the right maintenance a DSB can be a great addition where something like H2S won't ever be a problem.
Glad too see this post is still going on because it is like the discussion I have in my head. I am concerned about wate accumulation and keeping a healthy system that is good for my fish. I know this goal is easier than keeping coral happy and growing, but my emotional investment is the same.
Coming to some sort of reasonable conclusion to this post will require that we develop a more quantitative understanding of the mass balance in our systems, i.e., material in versus material out. The notion that "waste builds up" does not help much because what we need to know is what waste, how much and how fast so we can take the appropriate action. Does carbon build up? Nitrogen? Phosphorous? Trace metals? What does vacuuming the substrate actually reduce and by how much? Can vacuuming be counterproductive to maintaing a healthy sand bed? How would one even begin to address these questions? If every system is different, how do I know which type I have?
As I said, this is a great post for me. Thanks.
Coming to some sort of reasonable conclusion to this post will require that we develop a more quantitative understanding of the mass balance in our systems, i.e., material in versus material out. The notion that "waste builds up" does not help much because what we need to know is what waste, how much and how fast so we can take the appropriate action. Does carbon build up? Nitrogen? Phosphorous? Trace metals? What does vacuuming the substrate actually reduce and by how much? Can vacuuming be counterproductive to maintaing a healthy sand bed? How would one even begin to address these questions? If every system is different, how do I know which type I have?
As I said, this is a great post for me. Thanks.
elegance coral
They call me EC
It doesn't need to be that complicated.
Any animal we keep in a small enclosure will make the bottom filthy. Hamsters, goldfish, birds, reptiles, saltwater fish, it doesn't matter. Stuff will build up on the bottom. We don't need to know whats in the stuff that's on the bottom, only that it's bad for the pet we're trying to keep. If we had a hamster, we wouldn't be concerned with the chemical composition of the waste that's on the bottom of its cage. We wouldn't worry about the carbon, nitrogen, phosphorous, or trace metals that it contains. We would simply understand that it's bad for the hamster, goldfish, bird, reptile........ and remove it from the container the animal lives in. It's no different for the very sensitive animals we keep in this hobby.
Unfortunately, we've had several authors make themselves, and the industry behind the hobby, a great deal of money by convincing hobbyist that they shouldn't clean up after their pets. A great number of animals have died and been replaced. An unimaginable number of snake oils have been sold to solve the countless problems associated with filthy tanks. This has been great for the industry, but horrible for hobbyists and the pets they work so hard to keep.
Any animal we keep in a small enclosure will make the bottom filthy. Hamsters, goldfish, birds, reptiles, saltwater fish, it doesn't matter. Stuff will build up on the bottom. We don't need to know whats in the stuff that's on the bottom, only that it's bad for the pet we're trying to keep. If we had a hamster, we wouldn't be concerned with the chemical composition of the waste that's on the bottom of its cage. We wouldn't worry about the carbon, nitrogen, phosphorous, or trace metals that it contains. We would simply understand that it's bad for the hamster, goldfish, bird, reptile........ and remove it from the container the animal lives in. It's no different for the very sensitive animals we keep in this hobby.
Unfortunately, we've had several authors make themselves, and the industry behind the hobby, a great deal of money by convincing hobbyist that they shouldn't clean up after their pets. A great number of animals have died and been replaced. An unimaginable number of snake oils have been sold to solve the countless problems associated with filthy tanks. This has been great for the industry, but horrible for hobbyists and the pets they work so hard to keep.
CStrickland
New member
:thumbsup:
Always a treat when EC pops into one of these threads and breaks it down
Always a treat when EC pops into one of these threads and breaks it down
Thanks for this viewpoint. As I have said before, I find these discussions useful. Here is another angle to explain why the pet waste clean up analogy might be incomplete (I understand it. I have three cats and two litter boxes or "crap factories").
The discussion around sand bed depths, vacuuming versus not vacuuming, and waste accumulation in an aquarium has not included a very important notion: growth efficiency. Growth efficiency is the amount of food consumed compared to the amount of growth or biomass generated. Animals need to consume more food than is needed to generate a given amount of biomass because they also need food to generate energy. Generating that energy is respiration and it converts food into CO2. But the importance of growth efficiency is not obvious until we include the notion of food chains. Uneaten food and feces from our display animals don't just fall to the substrate and accumulate. It is consumed by organisms with growth efficiencies less than 100%, and so, the passage of this food to the next consumer results in another loss of material through respiration. But the chain does not end there. The bacteria and the microorganisms that just ate and exported carbon from the system through respiration are eaten or attacked by virus and once again, biomass becomes available for consumption and is further reduced by another round of than less 100% conversion and loss to CO2. Unless food is continually supplied by you or algae, the system winds down.
There is some fraction of dissolved organic matter organic that is resistant to digestion and takes longer to covert to biomass and CO2. And these conversions take time. It is possible to add food too quickly and overwhelm the system.
Phosphorus and nitrogen levels exceed the amount needed to build biomass in the aquarium. Every link in the food chain generates a little more excess. The excess nitrogen tends not to accumulate because of denitrification. Phosphorus however is not exported so well and intervention is needed to keep its level down.
So, in principle if food import does not exceed CO2 export, the system is sustainable forever. If we hear about a system with a deep sand bed that has been around for years and years with little maintenance, that may not be so strange. To be fair, we also have to note that we don't know what part good fortune played in the longevity of such a system.
Unfortunately, we have virtually little insight into all those bioconversions to know whether they are being overwhelmed. Nor do we have any idea about the accumulation level of dissolved organic compounds. And on top of that, we don't know what vacuuming a substrate actually accomplishes beyond a very crude view that it removes something.
We are stuck in a rut with these substrate bed discussions. I am in the process of gathering chemical data on the sand and pore water in my fish only aquarium. I have a year old bed of fine silica sand that I do not vacuum. I plan on posting this information and hope others will become interested in making similar measurements and possibly bring useful data to the discussion.
Dan
LNell
New member
Your comparison is great if your only real concern is fish and corals (probably most in this hobby). For those of us that really enjoy the little detritivores that love all that filth, your comparison doesn't really fit. Thus it really comes down to what kind of system you want to create, and at what stage you want to export nutrients.
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