Are Deep Sand Beds, DSBs, dangerous to use in a marine aquarium?

[ReadyRock]

That's what I was thinking so just keep up with the sand bed and and you will not have such catastrophic incident happen

 

[Lavoisier]

Having a good assortment of worms, amphipods, nasarius snails, and other such sand bed fauna to keep stirring and processing the detritis/food in the sand bed is indeed key to a proper running sand bed

And it is just wise to replace 1/4 of your DSB every 4th year. Siphon it out and replace with new sand. You will avoid "old tank syndrome" and still gain the enormous benefits of your DSB.

 

[Devi]

I run bare bottom on some of my freshwater tanks to astounding success. My first saltwater tank was fairly shallow, maybe a hair under and inch and over the years less because of syphoning and cleaning. This time around I went very deep. In one place in the tank it is four inches easy. I did this because I wanted a particular blenny that needs the sand. I worry though. I know my work is cut out for me to keep the sand clean. When the tank is more established I am planning on adding an abundance of snails. I also plan on removing and replacing the sand slowly every couple of years.

However, I had an old 75 gallon deep gravel freshwater angel tank. I never did anything with that gravel. Well three years I noticed lots of gunk so I decided to vac it out. It was very clear something was bothering the fish, lost two and saved three. Since I had not done maintenance on the gravel it was a toxic sludge. I will not make that mistake again.

 

[jsweese]

While I hesitated a bit jumping in without reading all 743 posts, a few things bear consideration. One is that our understanding of nitrogen processing in aquaria is superficial, at best. There is likely pronounced variation between systems because of profoundly different environments and different microbial exposures. Knowledge of the microorganisms present in aquatic systems has been based on methods that we know are quite limited, and use of advanced methods (e.g. next generation sequencing) isn't very common.

Description of nitrification as aerobic and involving a small set of bacteria and denitrification as anaerobic is probably superficial if not incorrect. There are hundreds to thousands of different bacterial species in aquaria, and we don't know which ones are good/neutral/bad. While we know what some species can do, we don't know their relative contribution to waste processing. There's also likely a lot of functional redundancy....highly different microbial populations that can achieve the same thing.

Denitrification is often discussed as an anaerobic function. However, some aerobes (e.g. pseudomonads) may play an important role in denitrification, and those can be highly abundant in some aquaria. Understanding how the microbial population of the aquarium works is just like figuring out how the microbial population of the gut works, and it's not easy to do. Massive effort has been required to scratch the surface, and along the way, lots of dogma has been tossed aside.

Freshwater and saltwater cannot be directly compared, even though many of the same bacteria may be involved. Archeae seem to be very important for nitrogenous waste processing in freshwater (maybe more than bacteria), but they probably play a limited role in saltwater. Looking at freshwater data can be misleading.

Anecdotes are useful but given the profound variations that are present, you need to be wary in using them to say something is absolutely good or bad. I'm not saying anything that's written here is wrong, but the profound knowledge gaps need to be recognized, along with the fact that there are no magic cures and lots of inter-tank variation.

Scott

 

[Aquarist007]

<img src="/images/welcome.gif" width="500" height="62"><br><b><i><big><big>To Reef Central</b></i></big></big>
I'm sure you will be a very welcomed asset to this site
You might want to check out some of the threads in the advanced forum.

This thread could use your expertise or input
http://www.reefcentral.com/forums/showthread.php?t=2134105

 

[dlavallee]

Hi All,

Regardless of anyone's results and personal preferences, from my perspective as a newbie in reef aquaria, this has been a very informative thread! Scientific or not, I really appreciate everyone's input to this thread. To really apply scientific method to the questions raised about DSBs, I think there are too many variables that would need to be isolated to be able to rule out (or fail to rule out) any reasonable hypothesis. The best way to accomplish this would be to use a control so that a single variable can be tested at any one time; however, it is unlikely that many of us would be willing to do so. That being said, this thread is a valuable collection of ideas that are based on a great deal of experience. Thank you all for sharing your experience!

 

[dlavallee]

Question: Could the benefits of a DSB by accomplished in a refugium?

Question: Could the benefits of a DSB by accomplished in a refugium?

As a newbie, I am still in the planning and research phase of starting a reef aquarium. I have had fish only marine aquariums back in the 1980s but that was with under-gravel filters and such and the hobby is so advanced from that now..

What would you suggest a newbie start out with? DSB? Shallow sand, or none at all? Would you recommend one way or the other for the newbie because of their lack of experience as opposed to a different approach for someone with more experience?

My understanding is that the main benefit of a DSB would be the breaking down of nitrates by the anaerobic bacteria. A friend of mine who owned a reef aquarium store some 15 years ago had a huge display tank of 480 gallons and he explained that he was using a Jaubert Plenum under his DSB and that his nitrates consistently read zero. However, from what I have been reading, this type of system is not so popular any more. The owner/operator of my LFS suggested that a Jaubert system would be a "ticking time bomb."

What about having a relatively large refugium with a DSB/Plenum that is isolated from the main display? That way every so often (annually, bi-annually?) this system could be maintained by being disconnected, completely cleaned out and restarted. Thoughts?

I am guessing that there is something significant that I am missing here due to my lack of experience.. If that's the case, I look forward to being informed of this as well.

Thanks,

Dave

 

[CobaltBlue86]

Are Deep Sand Beds, DSBs, dangerous to use in a marine aquarium?

I hate sand. It very pretty and all but IMO it's just a big cesspool of crap that you have to siphon out. I would either go barebottom or very shallow sand bed (half an inch). This way, if you want to clean the sand you can siphon it all up, wash it with RODI, let it dry, then return it to the tank.

 

[Dog boy Dave]

I thouhgt it would be a good idea to post this article here for further discussion. I've read through it once and am still digesting the information - pun intended However this was always my understanding of how DSBs work and why I incorporated one in my latest system.

I feed rather heavily and never see an appreciable rise in NO3 and often need to give a a boost in order to maintain a PO4 level within an acceptable range.

Nitrogen Cycling Revisited: Sand, critters, carbon, and why you may be under-feeding your tank

Great Link and article. Thank you for posting that.

 

[Clown Tang]

It is a simple fact that any sand bed, regardless of depth, absorbs both nutrients from the water column as well as organic material from both micro and macro fauna. Look at any sand bed and you might (probably will) see a thin layer of darker colored material maybe an inch or so below the surface. This is organic matter than has been slowly moved down into the bed by those fauna. 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. If this toxic gas is released in any form, due to disruption or natural release, it can easily kill off fish. Simple as that. It is simple ecological and biological fact that this occurs. If you don't want to risk your expensive fish, don't try a deep sand bed.

Of course there are plenty of anecdotes where people have kept dsb's running for years, but there are also 90 year old smokers that never got lung cancer.

 

[KafudaFish]

It is a simple fact that any sand bed, regardless of depth, absorbs both nutrients from the water column as well as organic material from both micro and macro fauna. Look at any sand bed and you might (probably will) see a thin layer of darker colored material maybe an inch or so below the surface. This is organic matter than has been slowly moved down into the bed by those fauna. 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. If this toxic gas is released in any form, due to disruption or natural release, it can easily kill off fish. Simple as that. It is simple ecological and biological fact that this occurs. If you don't want to risk your expensive fish, don't try a deep sand bed.

Of course there are plenty of anecdotes where people have kept dsb's running for years, but there are also 90 year old smokers that never got lung cancer.

I think you are using the term facts wrong. There are very few facts regarding biological systems and even your statement regarding smokers does not support this.

It may increase the probability of the occurrence but it is not an absolute. For example, evolution is a theory and if enough scientific evidence is presented against it, this theory will no longer be supported.

Yes a system may release the gas but as long as the threshold has not been reached the system will recover.

 

[Reefin' Dude]

I think you are using the term facts wrong. There are very few facts regarding biological systems and even your statement regarding smokers does not support this.

It may increase the probability of the occurrence but it is not an absolute. For example, evolution is a theory and if enough scientific evidence is presented against it, this theory will no longer be supported.

Yes a system may release the gas but as long as the threshold has not been reached the system will recover.

What about the P? That is what is in question here. P is not released as a gas. How is the DSB to recover without the removal of P? Where is the export mechanism of P in a DSB besides mechanical removal by siphoning or major disruption of the substrate?

G~

 

[KafudaFish]

What about the P? That is what is in question here. P is not released as a gas. How is the DSB to recover without the removal of P? Where is the export mechanism of P in a DSB besides mechanical removal by siphoning or major disruption of the substrate?

G~

Never mind. I don't have the interest to have to read about poop in a toilet living and hamburgers analogies, your stock 1000 word responses that you have saved, the 50 links you have supporting your opinion, and the few graphs that you include on every thread related to this is or any other similar subject.


To be honest I am too lazy and don't care enough on the subject. I think some of your points have merit but your dogmatic approach does not allow you to do the same with others.

When you posted pictures of your tank and how well your system worked I took pause and must with all honestly would rather have a doomed system than your own.




For example you act like removal is cheating the system. Not sure why. As I wrote in a previous post one way vs two way street.

Good luck trying to win the war.

 

[Reefin' Dude]

Never mind. I don't have the interest to have to read about poop in a toilet living and hamburgers analogies, your stock 1000 word responses that you have saved, the 50 links you have supporting your opinion, and the few graphs that you include on every thread related to this is or any other similar subject.


To be honest I am too lazy and don't care enough on the subject. I think some of your points have merit but your dogmatic approach does not allow you to do the same with others.

When you posted pictures of your tank and how well your system worked I took pause and must with all honestly would rather have a doomed system than your own.




For example you act like removal is cheating the system. Not sure why. As I wrote in a previous post one way vs two way street.

Good luck trying to win the war.

And that right there is why the hobby is where it is right now. Zero information to support how a DSB "works", yet plenty of information about how they accumulate waste organic material. Another great proponent of DSB's that chooses to ignore these facts and tries to use smoke an mirrors to avoid the "hard" questions.

As has been asked countless times in this thread and others. All we are looking for is some basis for how a DSB works long term. Give us a bone here to support your position instead of just saying we are wrong and ignoring the information posted that DSB's accumulate waste organic material. Some information about how to even setup a DSB for long term use is a start. There is zero current information out there for a reason. They do not work the way as advertised.

I will again say that it is not the sand that is bad, but is the accumulation of waste organic material that is the problem in some environments we try and emulate in our systems.

G~

 

[tmz]

Where is the export mechanism of P in a DSB besides mechanical removal by siphoning or major disruption of the substrate?

As stated many times in a long tedious perseverative discussion earlier in the thread , inorganic phosphate is miscible and moves via diffusion into the water column. If it didn't move out of the sand then it wouldn't bean issue .

To iterate briefly for those who haven't read the whole thread:

some of it is sunk for millennia in the crystal matrix of the aragonite ,

some of it is bound to calcium carbonate surfaces and equilibriates with levels in the water,

some of it is released when organics degrade,

some of it comes from waste generated by organisms,

some of it is released when and if aragonite dissolves in localized acetic conditions.

 

[billsreef]

What about the P? That is what is in question here. P is not released as a gas. How is the DSB to recover without the removal of P? Where is the export mechanism of P in a DSB besides mechanical removal by siphoning or major disruption of the substrate?

G~

No one has have said a DSB magically removes P or precludes the needs of other mechanisms to remove P. P doesn't magically get removed from BB tanks either, so arguing against DSB's on the basis of P is rather pointless. A DSB should really only be looked at as another tool to be used in aquarium husbandry, that can (and in most cases should) be combined with other tools such as protein skimming, GFO, etc.

Zero information to support how a DSB "works",

There is a good bit of information out there, some even in this thread.

 

[tmz]

This article linked originally in post 737 by Bilk provides an excellent overview of the nitrogen cycle:


http://www.advancedaquarist.com/2014/5/chemistry

This author's opinion from it is unclear in part and debatable:

"...Although at times the presence of a sand bed is a contentious issue, I would argue that having a sand bed is a necessity for natural nitrogen cycling (please note, however, that I am not claiming that natural nitrogen cycling is the only valid aquarium husbandry method)...."

Sand certanily provides surface area for bacteria so it's clearly useful in that regard but there is no indication of depth noted in the author's opinion.

Deep sand is likely to be starved for organic carbon and other elements without bioturbation or another force to move them into it. The bacteria are heterotrphic as the author notes ;but, he does not note their faculatative quality. They use oxygen and create hypoxic areas even in their own mats sufficient for anaerobic denitrification to occur.
Most of the anaerobic denitirification will occur in the first half inch or so (as evidenced in other studies cited in this thread) if sand is used and can and enough can occur on other surfaces without any sand at all.
Further, IMO, using sand is no more natural than not in the context of a closed system like an aqaurium. It's mostly an aesthetic choice or one taken to accomodate certain animals that may need it ,IMO.







This opinion from it is a bit unclear and debatable ,however:

 

[Fredfish]

... and if you want to dig a little deeper than Tom's summary you can always read this article.

A deep sand bed is neither the be all and end all or the devil's spawn. It is a fun thing you can add to your system should you be so inclined.

 

[Reefin' Dude]

Where is the export mechanism of P in a DSB besides mechanical removal by siphoning or major disruption of the substrate?

As stated many times in a long tedious perseverative discussion earlier in the thread , inorganic phosphate is miscible and moves via diffusion into the water column. If it didn't move out of the sand then it wouldn't bean issue .

In order for diffusion to work out of a substrate, there must more inorganic phosphates in the substrate.

To iterate briefly for those who haven't read the whole thread:

some of it is sunk for millennia in the crystal matrix of the aragonite ,

Are you suggesting that life on Earth should have died out long ago from all of the P that is now sunk in the matrix of aragonite, never to be accessed again?Are you saying that PSB are not able to access this P?

some of it is bound to calcium carbonate surfaces and equilibriates with levels in the water,

For equilibrium to occur with the water column, there must be more P bound to the aragonite, correct? How is this not contradictory to what you said in the previous point?

some of it is released when organics degrade,

ABSOLUTELY!!! All that I have been saying. The decomposition of the waste organic material is releasing inorganic N, P, and CO2. For the "diffusion" to work there must be more in the substrate, than not. Isn't this another indicator that there is an accumulation of P in the system?

some of it comes from waste generated by organisms,

Agreed.

some of it is released when and if aragonite dissolves in localized acetic conditions.

From the increase in CO2 from all of the decomposition of the waste organic material dropping the pH. Though I thought earlier this P was sunk for a millennia. Now it is released through local acetic conditions.

No one has have said a DSB magically removes P or precludes the needs of other mechanisms to remove P. P doesn't magically get removed from BB tanks either, so arguing against DSB's on the basis of P is rather pointless. A DSB should really only be looked at as another tool to be used in aquarium husbandry, that can (and in most cases should) be combined with other tools such as protein skimming, GFO, etc.



There is a good bit of information out there, some even in this thread.

What I have been saying all along. It is a tool. Like any tool its pros and cons need to be understood and used accordingly. Substrates are fantastic at accumulating waste organic material. This is known. We just need to maintain a substrate like any tool we wish to use. It needs to be cleaned on a regular basis based on the desired level of inorganic P and N.

Skimmers, GFO, carbon dosing, and ATS, they are all different tools. It is a good idea to know which form of nutrients they remove and where those forms of nutrients they remove initially come from.

... and if you want to dig a little deeper than Tom's summary you can always read this article.

A deep sand bed is neither the be all and end all or the devil's spawn. It is a fun thing you can add to your system should you be so inclined.

What I have been saying. If one wants to have a substrate, great, but one must understand that they do accumulate P over time and this needs to be accounted for.

G~

 

[tmz]

There you go again. Misrepresenting and convoluting the obvious. It's a two way street for soluble reactive phosophate in and out of the sand ; some is sunk for thousands upon thousands of years. You asked how the phosphate moves out of a sand bed in a context implying it doesn't. My statements are clear and consistent. There is a difference between phosphate bound to the aragonite surface and phosphate encased in the crystal. No do overs ;enough was already said in pages of endless gibberish earlier on in the thread. "Are you saying?" No any reasonable person would find any of the nonsense you introduced in my statement. Read what I said not what the strawman in your mind said.