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

[tmz]

Quote:
<table border="0" cellpadding="5" cellspacing="0" width="100%"> <tbody><tr> <td class="alt2" style="border:1px inset"> Originally Posted by tmz
vacuuming of the substrate is the only way to remove P

Agh, While I personally, think siphoning some detritus is useful as a means of export . It is not the only way.
</td> </tr> </tbody></table>
never said it was the only way.

and

vacuuming of the substrate is the only way to remove P

Huh??????

 

[tmz]

What do you mean by early days? I started my first 20g freshwater with an undergravel filter in 1971! This was a well constructed experiement done in 2005 (http://www.advancedaquarist.com/2005/6/aafeature)

That study by Toonan et alia(cited earlier in the thread IIRC) was pviotal for me . The major critique offered by some, rightly so or not, was that there were no sand critters employed for bioturbation and bioirrigation for the deeper beds thus limiting the activity in the deeper areas and thus not a fair representation of standard deep sand bed applications.

 

[Lavoisier]

What do you mean by early days? I started my first 20g freshwater with an undergravel filter in 1971! This was a well constructed experiement done in 2005 (http://www.advancedaquarist.com/2005/6/aafeature)

That study by Toonan et alia(cited earlier in the thread IIRC) was pviotal for me . The major critique offered by some, rightly so or not, was that there were no sand critters employed for bioturbation and bioirrigation for the deeper beds thus limiting the activity in the deeper areas and thus not a fair representation of standard deep sand bed applications.

Yes, I think the focus of the study was quite focused and limited in its application to our current conversation. I am suggesting that there are good empirical studies that are accessible to we hobbyists which may shed light on a subject that is complex and difficult. The startling result with these two papers to me was the fewer organisms that died in the DSB tanks. Another example may be http://www.advancedaquarist.com/2014/5/chemistry. I have not fully digested this article but initially find it relevant and hope it will add to my understanding of the complex niche I am attempting to model in my reef aquarium.

 

[asylumdown]

The nutrient content of a reef is astoundingly high... But the water is clean... Long as the water in our tanks is filtered and remains clean, what's the dillema? The waste gets recycled via different organisms eventually and the filtration and husbandry maintain water quality while it is happening. Our mechanical and physical(water changes) filtration are like the tide that washes the dirty water away.

This is a very important statement. The one thing that hasn't been talked about at all in this thread, however, (that I hope someone like Amphiprionocellaris studies one day) is allelopathy. It's not an issue specific to sand beds per se, but there's a near infinite number of organic chemicals produced by organisms on the reef, and the number of them that we as hobbyists can test for amount to maybe one or two grains of sand on all of Venice beach. We know that organisms like cyanobacteria and corals produce a cornucopia of chemicals for the sole purpose of waging war on competitors and maintaining an environment suitable to them, and basically none of these chemicals would appear in most tests unless you knew exactly what you were looking for and had highly specialized equipment. Cyanobacteria in particular are notorious for producing chemicals we'd consider 'toxins', and seem to have extreme flexibility both in the timing and volume of production of said toxins (i.e. cyanobacteria related chemicals that are toxic to humans are not produced all the time under all circumstances by the organisms that make them).

I've always had a healthy suspicion that when everything else is equal, some of the issues people have witnessed with sand beds, or any part of marine husbandry really, are related to a shift in organisms that were always present but either behaved differently, or were present at different levels. If you've ever battled the biofilm form of cyanobacteria before, you'll know that your levels can all test spot on, and yet the cyano advances, killing everything it touches. While the macro organisms that burrow about in sand beds are probably pretty benign, there are single celled organisms that can 'infect' (for lack of a better word) a sand bed that can assuredly produce substances capable of causing major problems in a tank. We'd not be able to test for any of that, and you don't see people discussing that element very often.

 

[asylumdown]

What is needed is to break down the scientific jardon to everyday speak. That's what's missing.

Scientists don't invent complicated ways of describing the world because that's what gets them off. They describe the world in complicated language because the phenomena they're trying to describe are complicated. They're also typically far outside the realm of what most 'normal' humans tend to think about in their every day lives. If our economy was based off some fundamental principal from organic chemistry, I promise you, O-Chem wouldn't be every biology undergrad's worst nightmare.

It sounds reasonable to insist that science reduce everything to "easy to grasp" digestible soundbites. But that creates the incentive to equate every single thing that happens in the natural world to some reductionist analogy that either does a poor job of explaining the phenomenon we're trying to understand, or is flat out wrong and misguides human thinking (sometimes for centuries).

The world is complicated. It is governed by complicated processes that interact with each other in ways so vastly confounding, even the most literate scientist will never come close to grasping the full meaning of things. Yes, it would be wonderful for our civilization if we could boil down complex biochemical processes to simple analogies and descriptions that were conveniently tailored for understanding in colloquial english. But the emergent properties of a billion mindless organisms reciting a chemical sonnet in a language so alien to human thinking it may as well be magic - couldn't give two whits whether or not the process was easy for us to understand, or translatable into the same words we use to buy groceries.

Scientific discovery, by its very nature, involves discovering things we do not yet know. And therefore things we do not yet have good language to describe. Forcing us to invent new ways to describe processes that have no good metaphors in 'every day' life. It's our responsibility as 21st century humans to do our best to learn the terms and concepts behind the new language science is giving us, not for science to dumb itself down to our Shakespearean understanding of language and reality.

I do have a great understanding of this subject (as a non scientist like you) but I choose not to get involved because there seems to be enough "experts" out there.

What is a "scientist" to you? Someone who's gone to "science" school? What is "science" to you? Some of the greatest scientists in human history had little more than a burning need to understand the world, and access to the tools necessary to answer their questions. You don't need a Bachelors of Fish Tanks to be an expert in aquariums. You just need to know what you can actually say you know, and what remains to be discovered.

mmmkay. My soapbox is back in my closet for a while.

 

[GroktheCube]

This is a very important statement. The one thing that hasn't been talked about at all in this thread, however, (that I hope someone like Amphiprionocellaris studies one day) is allelopathy. It's not an issue specific to sand beds per se, but there's a near infinite number of organic chemicals produced by organisms on the reef, and the number of them that we as hobbyists can test for amount to maybe one or two grains of sand on all of Venice beach. We know that organisms like cyanobacteria and corals produce a cornucopia of chemicals for the sole purpose of waging war on competitors and maintaining an environment suitable to them, and basically none of these chemicals would appear in most tests unless you knew exactly what you were looking for and had highly specialized equipment. Cyanobacteria in particular are notorious for producing chemicals we'd consider 'toxins', and seem to have extreme flexibility both in the timing and volume of production of said toxins (i.e. cyanobacteria related chemicals that are toxic to humans are not produced all the time under all circumstances by the organisms that make them).

I've always had a healthy suspicion that when everything else is equal, some of the issues people have witnessed with sand beds, or any part of marine husbandry really, are related to a shift in organisms that were always present but either behaved differently, or were present at different levels. If you've ever battled the biofilm form of cyanobacteria before, you'll know that your levels can all test spot on, and yet the cyano advances, killing everything it touches. While the macro organisms that burrow about in sand beds are probably pretty benign, there are single celled organisms that can 'infect' (for lack of a better word) a sand bed that can assuredly produce substances capable of causing major problems in a tank. We'd not be able to test for any of that, and you don't see people discussing that element very often.

This is a very important point.

Most of the evidence I've seen suggests that the negative effects of inorganic nutrient buildup in an aquarium are not a direct result of the nutrients themselves, but rather giving certain organisms (generally algae) an advantage over corals and allowing them to cause damage. There's a lengthy thread in the SPS sub-forum where examples of tanks with extremely high dissolves inorganic nutrients with thriving "clean water" corals are posted.

Put simply, "nutrient buildup" in and of itself is probably harmless. It only seems to pose a problem when it facilitates the growth of organisms which are harmful to corals.

 

[asylumdown]

Put simply, "nutrient buildup" in and of itself is probably harmless. It only seems to pose a problem when it facilitates the growth of organisms which are harmful to corals.

Precisely. I know this is anecdotal (and therefore should be taken with a mountain of salt), but for the first year of my tank's life, I battled wave after wave of these really horrible kinds of algae. I had three or four distinct species of hair algae that would wax and wane, and this one weird kind of purple, almost gelatinous algae that would grow hairy nodules from a rubbery, elongated hold fast. Nutrients were always undetectable, husbandry practices were better than anyone would recommend, and yet I couldn't get ahead of it. My corals were also anemic, pale, and would recede from the bases and rarely grow.

In the winter of 2012 I dosed the tank with an algicide, and basically extirpated most algae species from my system. I didn't change anything else; I had the same fish, I fed the same foods, I changed the same amount of water, and used the same additives, but BAM! My corals changed colour in a major and positive way, growth kicked in to over drive, and the number of hours I needed to spend with my arm in the tank went from a couple a day, to a couple a week.

Things have fluctuated since then, but I've never seen anything as profound as eliminating problem pest species on the "health" (I say this knowing how relative that term is) of my system.

I've seen pictures of deep sand beds with luxurious sheets of red and green cyanobacteria between the sand and the glass, and I've always wondered whether or not that tank is just an unfortunate inoculation with a "toxic" species away from a total, yet seemingly unexplained crash. Then again, is any system?

 

[Zalick]

And there is still disagreement here.

I'm confused. How is there disagreement with: if you don't "take out the trash the tank will overflow"?

We are talking about the overall mass of our system. It either grows, shrinks or stays constant. Those are the only three options.

Without manual intervention, I believe our systems will grow in mass, not stay constant.

Our tanks are closed systems. We feed them. The mass we feed is converted to increased mass in the tank life, gas and heat. Here is a ROUGH equation:

To keep the equation clean lets assume the following:
1. We have no electronics/heaters in the tank which add heat.
2. The ambient room air does not heat the tank.
3. Heat only leaves the tank through the conversion of ATP to ADP (work) of the animals, as a product of photosynthesis of the corals and as chemical reactions in the water.


X = mass of initial state of tank
Y = mass of food fed to tank
Z = mass of gas + energy (heat) leaving the system

State 1: Tank beginning has mass X.
State 2: We feed it mass Y and stuff grows, increasing the biomass and producing Z.

Mass of state 1 = X.
Mass of state 2 = X + Y - Z

If the mass of our system is constant, then Y = Z. We know that's not true because 100% of our food is NOT converted to gas + heat. Some of it is stored as mass in the system because stuff grows. Therefore Y > Z and our final equation is:
X + Y - Z > X
proving that our system will continuously increase in mass without human intervention.

So if we don't need to manually intervene and export a portion of Y, how can our tank live in perpetuity? People who believe manual intervention is not necessary would eventually have a tank whose organic and inorganic mass displaces the water completely.


If someone has science to show me that my equations are wrong, I'm definitely open to seeing it.

* I know my equation is very basic but I believe it captures all the mass of our systems

 

[Paul B]

He now charges people per question posted to him. 5$ per question.

I am going to start charging $6.00 a question, but if you want a correct answer, I may charge $10.00, but maybe only $4.00 for a guess :dance:

 

[Fredfish]

What do you mean by early days? I started my first 20g freshwater with an undergravel filter in 1971! This was a well constructed experiement done in 2005 (http://www.advancedaquarist.com/2005/6/aafeature)

There are probably more out there that we have not taken the time to think through and apply to our systems.

Sorry, early days of deep sand beds. I thought Toonan did his experiment a few years earlier, so maybe I should have written halcyon days instead.

I have not seen anything since that work by Toonan.

I was quite happy to see Tommy's recent article. Hopefully this thread does not wear him down and we will see further writing from him.

FWIW, I had sticlebacks in '71.

 

[billsreef]

I'm confused. How is there disagreement with: if you don't "take out the trash the tank will overflow"?

No is really disagreeing that there needs to be ultimately some form of nutrient (trash) removal. It's really the processes involved being argued and idea of just how fast that ultimate removal needs to happen.

We are talking about the overall mass of our system. It either grows, shrinks or stays constant. Those are the only three options.

Anyone with growing fish and coral has the mass of their system growing If you frag corals and give them away or sell them, you just exported nutrients from your system

As an aside, for those challenged by scientific terms (even when using them)...

SRP = Soluble Reactive Phosphate. This includes both reactive inorganic Phosphate and reactive organic phosphate. It has been found that there are some forms of organic phosphate that are reactive, as well as some forms of inorganic phosphate that aren't....hence the term SRP being better than just using inorganic phosphate

 

[Fredfish]

I'm confused. How is there disagreement with: if you don't "take out the trash the tank will overflow"?

That was imprecise language on my part. I agree, in the end you need nutrient export of some sort.

The disagreement is over whether or not a sand bed accumulates nutrients in a dangerous way over time. Think Toilet, cesspool, sewage treatment plant etc.

Personally, I'm quite happy with the direction this thread has taken. I jumped in because the discussion was not particularly balanced: was heavily represented by one side of the argument.

There is now a good presentation of both views and plenty of information on which to make an informed decision on whether or not to choose a sandbed of some sort as part of the filtration for a tank.

 

[billsreef]

no, the wash away rate is much higher in nature. we ignore the importance of substrate movement in our systems. it is washed out to sea. put a stick in the sand at any beach and see how much of the sand moves in an hour. it is far more than some silly 4 inches that is said to be the optimal depth for a DSB. nature is moving literally tons more sand around than we are.

The rate of sand transport your seeing in your beach example is several order of magnitudes higher than what actually occurs out in the reef and the seagrass beds. You need to get diving You'd be surprised just how much you can find stirring up the sand at the base of a coral head.

.....
They work and require husbandry. Maybe they pose no additional benefit over a shallow bed.

Anectodally, I've found DSB's maintain lower NO3 with same basic feeding and ancillary filtration systems. I've also found DSB's seem to make the tank more resilient to some things...like coming home to find young kids have dumped entire (and rather large) cans of fish food in the tank, only to have the life in the sand bed assimilate it all with no bumps in nutrient levels. No more work involved, unless you move and need to break down your tanks.

I am going to start charging $6.00 a question, but if you want a correct answer, I may charge $10.00, but maybe only $4.00 for a guess :dance:

Dumb looks free? :beer:

 

[elegance coral]

How does it impact the corals and not get into the water column?

Man I wish I had more time to post. Sorry for the delayed response.

I never said it doesn't get into the water column. In fact, I explained how it does get into the water column.

They are adding P to the water column. Not "removing it from the water column". These are reducers/decomposers. They take solid organic particles from the sand and dissolve it as it passes through their digestive systems. They take the solid food we feed, break it down, and release the elements it contained (like P) into our water.

We take steps to limit the accumulation of these harmful substances in our water. I'm just trying to point out that we're ignoring a huge portion of the equation by not limiting these same substances in the sediments (sand and rock) where we attempt to grow some of natures most delicate creatures.

 

[Randy Holmes-Farley]

I never said it doesn't get into the water column. In fact, I explained how it does get into the water column.

So when it does, why can't GFO, organic carbon dosing, macroalgae, skimming, creature growth and other methods be suitable to export it before it rises to troubling levels?

Obviously that works as people with sand beds are able to keep phosphate adequately low.

 

[Zalick]

That was imprecise language on my part. I agree, in the end you need nutrient export of some sort.

The disagreement is over whether or not a sand bed accumulates nutrients in a dangerous way over time. Think Toilet, cesspool, sewage treatment plant etc.

Thanks for the clarification. So the question really is:
Do the critters in the DSB and the properties of the calcium carbonate structure process 100% of the waste/food (Y-Z) in my example, causing it to either increase the mass of the critters or be returned to the water supply for skimming/removal?

Personally, I'm quite happy with the direction this thread has taken. I jumped in because the discussion was not particularly balanced: was heavily represented by one side of the argument.

There is now a good presentation of both views and plenty of information on which to make an informed decision on whether or not to choose a sandbed of some sort as part of the filtration for a tank.

I agree. Couldn't sleep list night and read through this thread for about the 2nd or third time in the last week or so. My formal education is biology and math with a touch of physics and chemistry. But that was nearly 20 years ago and I never worked in those fields. This type of discussion is both intellectual and informative for hobbyists!

 

[howaboutme]

So when it does, why can't GFO, organic carbon dosing, macroalgae, skimming, creature growth and other methods be suitable to export it before it rises to troubling levels?

Obviously that works as people with sand beds are able to keep phosphate adequately low.

Isn't (one of) the point that's being made is that all of those interventions are not enough over X amount of time? I guess a question is what is X? Is X a 3 year old DSB w/ obvious signs of H2S or a 10yr old DSB still going strong today but may crash tomorrow?

 

[elegance coral]

It doesn't work that way man..... QUOTE]
Well, unless it does.

Well, thankfully it doesn't.

It certainly does in rain forests.

You honestly believe there are bugs and worms lying on the forest floor just waiting for a leaf to fall from the sky so they can feed??????

The forest floor does work like a DSB, but again, it does not work the way you believe it does.

The bugs and worms on the forest floor live in a giant smorgasbord we call leaf litter. They need not concern themselves with the leaf that falls today. Leaves fall every day, animals die every day, animals defecate every day, and all of this organic matter builds up on the forest floor. It can take months for the organic matter that fell to the forest floor today to completely rot away. This means the forest floor is holding months of accumulated rotting matter. These bugs and worms are feeding on the remains of the leaf that fell last week or several months ago. Rotting organic matter accumulates on the forest floor, just as it does in a DSB. Bugs and worms feed on this organic matter, but they can not stop the accumulation. In fact, their populations will be directly linked to the amount of accumulated organic matter. In areas where there is an abundance of rotting organic matter, there can be large numbers of reducers/bugs and worms. In areas where the accumulation is sparse, these organisms will also be sparse. This same effect takes place in DSBs, and virtually every other environment on the planet. In order to support large numbers of bugs and worms that feed on rotting organic matter, you must have large amounts of rotting organic matter to feed them.

It takes time for organic matter to break down. People are posting in this thread as if a worm eats a scrap of food, or piece of fish poo, and the story ends there. The scrap of food or fish poo is now gone because a tiny animal ate it. Well, again, that's not how it works. That tiny piece of food may be eaten and defecated many many times, by many many different organisms, before it is completely dissolved away and leaves the sand. This takes time. The elements in that piece of organic matter that fell into the sand today may be passed from organism to organism, and from organic to inorganic forms, many times before it eventually leaves the sand. All of this takes time. Throughout this time, new organic matter is constantly being added to the sediments and the process continues. The organisms living in a DSB can no more keep the sand clean and free of rotting organic matter than the organisms living on the forest floor can keep it clean and free of rotting organic matter. Rotting organic matter accumulates and builds up on the forest floor, in spite of all the tiny creatures that feed on it, just as rotting organic matter builds up in a DSB, despite all the tiny creatures that feed on it.

There are people, Bill being the most recent to post here, who have successfully kept deep sand beds for years without issue or major interventions. I dunno, maybe Bill and those others don't exist.

Have you been reading this thread at all???? We have gone over this many many times. The fact that Bill was able to keep animals alive in a system that contained a DSB proves nothing. Maybe it says something about his skills as a hobbyist, but it says nothing about how a DSB effects a tiny glass box full of delicate animals. There are many variables that can effect the success or failure of a marine aquarium. We can not choose one aspect of Bill's system, like the DSB, and say that Bill's system was successful because of the DSB. We could just as easily say that Bill's system was successful in spite of the DSB. In order to state that Bill's system was successful because of the DSB, we would have to explain how and why his success was linked to the DSB. Science and nature won't allow us to do that.

Ow..... And BTW...... Bill does take steps that limit the amount of rot and decay his sand bed harbors. This is contrary to the typical Shemik style DSB method.

 

[Amphiprionocellaris]

I'll address a few of the previous points below, but at this point I kind of feel like I'm repeating some of the same refutations over and over without them actually being understood properly. Which usually tells me that I'm not teaching appropriately, but I'll give it a go before I retreat back into my writing cave.

SRP soluble reactive phosphorous. inorganic p. what good is algae to us then if it is able to uptake organic P? nobody is denying that algae is able to convert SRP to organic. once it is converted to organic again, then what happens to the P? if it keeps going around and more food is going into the system, then there must be an increase in total P.

If we ignore the portion removed by filtration, sure.

because they are. space and oxygen are not niche resources. they are in the same box, they have to be competing for resources. again, recycling is not exporting. what organism in our systems eat the worms in the substrate that is in the water column? how does the nutrients contained in benthic organism get out of the substrate, whether it is dead or alive? simple question.

Simple question with a simple answer: the organisms within the sediment break down organic molecules into smaller ones that diffuse or are advected out of the sediment to be removed by uptake or filtration. I've said that at least a dozen times by this point.

waste organic P, whether it is poo or dead organisms, does not just magically become SRP. bacteria decompose it. so, what happens to the bacteria? how does that bacteria become SRP? all the while more waste organic material coming into the system/substrate. in order for any of that 38% organic poo phosphate to become more SRP, there needs to be bacteria.

The bacteria die eventually, reverting to organic matter, which is decomposed into the particles and molecules that can be removed by filtration. Of course, the biomass produced represents only a tiny fraction of the OM being decomposed; for every 1 gram of new bacteria, there's 100 grams of organic. And then of course, assuming a constant rate of input to the tank and proper use of GFO, etc, there's a good chance the bacterial population is at steady state, in which case we can ignore the production of biomass entirely in terms of net P movement (because it's a balanced equation; new growth = old death).

there has to be an export of organic P. the decomposing organism, the poo, the dead organisms. they just do not spontaneously become SRP. all of these organisms and material needs to be taken into account when discussing P.

Why does it matter which form is exported? If you want to maintain low levels of P, it doesn't matter whether you remove organic P or inorganic, it's still P removal. The only legitimate reason to consider total biomass is if you want to consider how much more dead matter will be created if the whole system crashes.

if you mean stirring up the substrate and vacuuming out the detritus, then yes it will result in the removal of P from the substrate. if not, then no. the only person i know of that uses irrigation in the substrate is Paul B. and i think that makes great sense. it goes with what has been said all along.

Wrong. I'd be happy to send you the dozens upon dozens of papers showing why this is wrong, but I do sum it up fairly well in my last article (at least in the section on benthic fauna) http://www.advancedaquarist.com/2014/5/chemistry
Paul's system is arguably a form of bioirrigation, just artificial rather than being generated by benthic critters.

you have got to be kidding us. we can see it when we stir up the substrate. what is all of that stuff in the substrate if it is not hidden waste organic material. are you suggesting that all of us are blind? there is nobody reading this that believes that waste organic material is not building up in the substrate. if it wasn't, then none of these magical benthic organism would have anything to eat. this material has to be getting into the substrate somehow.

Already addressed this: refractory waste, biomass, abiotic minerals etc. And there are quite a few people - myself included and I've been studying this for a long time - who believe that there is not a net accumulation of organic matter building up. You don't need to have a buildup of material to support a population once it's mature, just a standing pool. Having a standing pool is not the same as having a buildup.

back to the point i was making much earlier into this post. waste organic material does not magically become SRP. bacterial decomposition is necessary. there is going to be an increase in waste organic material if more waste organic material is coming in from above. the rate of breakdown is not able to keep up. that darn 38% over time problem.

This claim is unsupported; it is very possible that the rate of organic matter breakdown could keep up with or even exceed the rate of new input. I've addressed that in detail before, so anyone who wants to know more details could refer to my earlier posts.

the problem is that there is more going into than out of the substrate. it is a sink. it is not balanced. there have been several graphics showing that it is not a one way street. it doesn't matter if it is just a tiny bit or a whole lot being sunk, the point is that P is being sunk. more is coming in, than going out. something that is easy to observe.

As a system matures, sure there is more going in than coming out, because it takes a while for the different processes to balance, the populations to grow, and the tank to reach a steady state or quasi steady state. The claim that it is not balanced is not supported, because it completely ignores steady state equilibrium. Again, refer to previous posts. One real question that's not being thrown around is whether a tank actually achieves a functional steady state, and that's open for discussion. It probably doesn't in the strictest sense, but oscillates around a steady state due to small variations in supply and export.

the science is the same for all systems. it shouldn't matter if the system is BB, DSB, SSB, RUGF, it should all be easily explained using the same science. if not, then why not? all anybody can do is give someone all of the information that has gotten them to their decision. give someone the key words necessary to do their own research, at their own pace to see what makes the most sense to them. nobody should be offended for asking dumb questions or for asking for more clarification. we can all agree that if you have a question, that somebody else probably has the same question.

G~

The frustrating thing is when we get the same questions or points to rebut over and over, restated as if they are new, yet the answers are ignored, and the cycle repeated. The good side is that this seemingly never-ending cycle, frustration aside, has given excellent directions for more articles, because there are a lot of interesting aspects to address and I can see clearly where proponents of sand beds need to better articulate some concepts.

 

[KafudaFish]

-------》 vs 《-------》

Depending on which arrow you pick, it should provide each person with his or her own answer to the original question.