Deep Sand Bed -- Anatomy & Terminology

[Paul B]

Paul, I love your tank.

Well, thank you

Would I consider it an accurate representation of a pristine tropical coral reef? No. I don't believe that is what you were shooting for in the first place though.

Correct.

Most hobbyists, especially here in the new to the hobby forum, strive to avoid algae. It is welcome in your tank.

It is welcome in my tank but unfortunately right now there is very little of it.

One of the largest sources of algae nutrients is detritus.

Yes and no.
Detritus which is a combination of bacteria remains and un dijestable parts of plants along with "creature" shells becomes inert after a while.
After a crab deterates, it's shell will remain a long time, this will not feed bacteria or add to tank pollution. Pods which make up a substantial part of the "creatures" in a tank also shed their shells. In a tank such as mine this has been going on for a very long time.
I am sure that all through my gravel are the remains of almost everything that I have kept in the tank since Nixon was President. Maybe even parts of him are in there.
In any case, I think what I am trying to say is that, in my tank with all the old detritus, I have almost no algae and almost no nitrates. I also rarely change water.
The food that the "creatures" such as pods eat do come out of them as Pod Poop (cool phrase) but that Pod Poop will be eaten or de composed by smaller animals and bacteria. Some of it, the un digestable parts will become detritus (that will eventually become inert) and the rest of it will end up as nitrate. Some of the nitrate will again become processed by bacteria to nitrogen gas and the rest will be removed through water changes.
So IMO, pods, which are eating what is basically left over, do not contribute to the nutrients of a tank. Or if they do, it is very slight.
I know what you mean that they are living animals and should contribute to the living biomass of the tank but then so should bacteria.
Of course I am not the God of Pods so I could be extreamly incorrect and I should go and shoot myself and feed my remains to the older, skinnier, less good looking pods in my tank.:wave:

 

[longfellowship]

Before I start let me give a disclaimer. I'm a scientist who is fairly new to this hobby. My statements here are based on the fact that pretty much everything I partake in, I research to the hilt. I prefer scientifically laid out cases to antecdotes. Personal stories are useful when they make us ask questions why and lead to researched facts. Personal stories on their own are meaningless. The web is full of opinions on how to do this hobby. Much of it is regurgitated perpetuated myth. I found Dr. Shimek by asking "Where did you get that information?" everytime a technique or opinion was laid out. Personal stories are good gauges on how to do or not do something exactly as the story teller has experienced (a crapshoot to match exactly). More experience puts more into that bank, but by nature it is limited. The better approach if you wish to understand the vast complexities of this hobby (or any other complex matter) is to keep asking why till you get to well researched facts and develop trust in those that do the same(greatly speeds up the process). That has definitely happened for me with Dr. Shimek. He is not the only one, but his devotion to providing research and guidance(based on research) to this hobby I have not seen matched. If anyone can point to someone else who does the same I would be happy to look at it.

A good overview for further reading:
http://www.reefkeeping.com/issues/2003-01/rs/feature/index.php
and
http://www.reefkeeping.com/issues/2003-06/rs/index.php


Physics (while still valid in this case) is not the appropriate science to reference. Ecology and Marine Biology would be better. These are two areas that Dr. Shimek is an expert beyond anyone here. An expert who has done field studies on reefs before many of us were born. He backs up everything he says with a study. If there is no study to support an opinion of his, he says so (before he answers a question). If there is no study to back it up he most certainly doesn't write an article about it. The pristine reef idea without myriad of small (mostly barely visible) animals is not found in nature (though coral branches covering the sand floor, poor visible resolution of our eyes or video, or the fact that much of this fauna is nocturnal when few videos are made makes this a convincing myth).

Regarding Physics, a simple reading of some of Dr. Shimek's most basic works tells the full story. Yes every animal that consumes poo also makes it. But they consume some energy along the way and export it in many ways. Some of it is released as CO2, some is put into the nitogen cycle. The nitrogen cycle must end in export of some kind of course. In the case of a DSB you will see N2 bubbles coming up out of the sand and to the surface and into surrounding air. JUST LIKE IN NATURE. The other forms of nutrient export that Dr. Shimek advocates is macro and foam fractionation (protein skimmer). A well functioning DSB will have 0ppm nutrient readings without much work.

As far as appearances go, most of the 1000's of creatures Dr. Shimek speaks about are so small that one must pay close attention to notice them. Worms are the noted exception, but there's no reason they have to get out of control aesthetically either.

The point is that if a DSB is functional the detritus should not be piling up. There will be some visible, but it will be taken through the natural cycles found in nature very quickly. The only detritus visible will be that on its way out of the tank through various ecological pathways.

A well functioning sand bed is achievable with proper selection of biodiverse fauna sources and minimizing predation risk.

Now all of that being said a DSB is not for everyone.

If your tank footprint is less than 4 to 6 square feet, maintaining the biodiversity will take more frequent seeding and monitoring and therefore a DSB may not be for you.
If you don't like the consistent, yet under control detritus, a DSB is not for you.
If you really want to keep decorative shrimp, hermit crabs, large sand sifting stars, or other DSB infauna agressive predators, its probably not for you.
If you enjoy siphoning your tank weekly it may not be for you.

However,

If you want to be able to feed the quantity of food that your creatures experience in nature and allows them to thrive, without fouling the tank or aggressive expensive filtration (a well functioning DSB is hard to beat in the load it can handle) it may be for you.
If you want to siphon your tank rarely, it may be for you.
If you want your tank to function as close as possible to nature with minimal technological intervention, it may be for you.
If you want to provide daily high quality live food to your reef inhabitants through consistent larval dispersion pretty simply, it may be for you.

The reef in nature and in our tank are more resilient to errors and changes when biodiversity is maintained.

Cheers,

JD

Human nature makes it easier to keep an open mind when we have not gone public with an opinion. This is my first opinionated post in any forum after more than a year of research. That means it will take a lot of evidence to change my mind :fun2:

 

[Paul B]

Longfelowship, first of all, nice to meet you and thanks for posting.
I am not a scientist but have had the same reef tank running for a few months short of 40 years. I am also the same age as Dr. Shimek and we started in the hobby the same time, that is the week salt water fish became available in the US in about 1971. (I have also been diving longer than that.)
I also have written many articles, OK so not in scientific journals
Just aquarium magazines.
Anyway, That is my disclaimer.
He is a respected name in the hobby and you are correct, he researches everything he publishes.
However, this "hobby" has problems when it comes to scientific research.
I have read many things the Dr. has written and it is all true, kind of.
On his thoughts about DSBs he is perfectly correct, for a while.
He states that in a DSB the fauna will make channels in the sand to allow water to get to the bacteria so it can be processed. That is true, for a while.
But in my un scientist mind, I know that those animals in a captive envirnment will not reproduce forever. As a scientific study such as Dr Shimek does lasting a few months to a couple of years it sounds great, but some of our reefs are decades old and the scientific studys fall short.
I also believe that a DSB works great for a few years then gradually ceases to function. (I used one in the 70s)
I can offer you the proof that I know as a scientist you need. Out of the 20,000 or so people on here and other forums, I don't think you will find more than 2 DSBs older than ten years old that are still functioning. There have been tens of thousands of them set up. I of course am not a researcher or scientist and I am sure you can quote vastly more scientific fact than I can. I am rather jealous of that and have great respect of scientists and am in no way trying to contradict your post.
As I said, I am glad you joined, we like brains here so again, welcome.

 

[Plan>B]

EC,
I'm sorry but you couldn't be more wrong. I will agree that if you have plague like proportion of critters, than you certainly have too much food in the system.
Other than that, there must be pods, worms and other fauna in the system to make the DSB function and remain maintenance free.

Here is a portion of information from Dr Ron Shimek's website on a DSB:

Rapid bacterial growth rates only occur without competition for space or nutrients. As the bacterial populations fill in all the open spaces growth slows and may stop altogether. Some bacteria also secrete a exterior covering called a "glycocalyx." These glycocalices are made of a hard sugar-like material similar in consistency to rock candy. Rapid bacterial growth may produce so enough of this material to glue sediments together. These sediment lumps may be glued so tightly together that hammering is needed to break them apart. In much reef literature, these lumps are said to be caused by calcium carbonate or calcium phosphate precipitation. Such mineral precipitation is rare; if a small sediment lump is placed in a weak solution of household chlorine bleach, it breaks down to the component sediment grains in a short time. If the lumps were formed from the calcium salts, they would not dissociate in the bleach.
Lump formation is a disaster for the biological filter. The lumps restrict water flow and trap organic material where it can rot. Additionally, lump formation shuts down the biological filter by covering the bacteria and preventing them from metabolizing nutrients. This, in turn, causes the tank nutrient levels to skyrocket.
Fortunately, prevention of sediment clumping and the simultaneous maintenance of optimal biological filter operation is easily done by the establishment of a healthy and diverse sediment dwelling fauna, or "infauna." The infauna, so-called as the FAUNA lives IN the sediments, is a very diverse array group of wonder-working organisms. Unfortunately, they are small, and are not particularly attractive. Like Rodney Dangerfield, "They don't get no respect." And, that is a pity, as they do most of the work in keeping any reef tank functional.
The infauna are "the clean-up crew" and the "reef-janitorial" staff, and the array found in a successful tank may be DIVERSE! More than 200 different species commonly are found living in a mature sand bed. These include many types of flatworms, round worms, dozens of species of bristle worms, small snails, brittle stars, small sea cucumbers, protozoans, and many types of small crustaceans. The total populations may be immense. I have done sampling to measure the abundances found in the 45 gallon tank I mentioned earlier, and the number of animals larger than half a mm, or about one fiftieth of inch, in that tank ranges from 90,000 to 150,000 depending on what part of their population cycle the various species are in.
What does this diverse and abundant array of critters do for and in the sand bed? Well, some will eat excess food, detritus, or algae. In doing so, they utilize it, and excrete part of it as waste. In turn, bacteria utilize that, and thus the infauna help keep the biological filter going. Additionally, many infaunal animals burrow ingesting some sediments as they go. They digest the microorganisms off of them, opening space for bacteria to grow.
By moving through sediments, the animals jostle and move the particles. Not much, just a little tiny bit. It has been estimated that each day each small organism moves about 10 to 100 cubic millimeter of sediment. Multiplying this tiny average amount of jostling by the number of animals in the tank gives the total amount of disturbance. In my 45 gallon tank, with an average population of about 100,000 small animals, from one to ten million cubic millimeters of sediment is moved each day! Or phrased another way, the entire tank's sediment volume could be completely turned over at least once every three to thirty days. With this amount of jostling and sediment eating, sediment clumping the sediments will simply not occur.
Consequently, excess food is eaten and disposed of or recycled as animal or algal flesh, and that the biological filter is maintained in the best of condition. And, best of all you, as the aquarist, didn't have to do anything. The animals did it all for you. All you had to do was to sit back, and enjoy a healthy tank. And, yes, I know it was a dirty job, but somebody had to do it...

Here is a link to the full article and the rest of his site:
http://www.ronshimek.com/deep_sand_beds.html

Great read... but just so I fully understand... one would never be able to have a sand sifting goby? What about after is was a few months old?

 

[longfellowship]

Longfelowship, first of all, nice to meet you and thanks for posting.
I am not a scientist but have had the same reef tank running for a few months short of 40 years. I am also the same age as Dr. Shimek and we started in the hobby the same time, that is the week salt water fish became available in the US in about 1971. (I have also been diving longer than that.)
I also have written many articles, OK so not in scientific journals
Just aquarium magazines.
Anyway, That is my disclaimer.
He is a respected name in the hobby and you are correct, he researches everything he publishes.
However, this "hobby" has problems when it comes to scientific research.
I have read many things the Dr. has written and it is all true, kind of.
On his thoughts about DSBs he is perfectly correct, for a while.
He states that in a DSB the fauna will make channels in the sand to allow water to get to the bacteria so it can be processed. That is true, for a while.
But in my un scientist mind, I know that those animals in a captive envirnment will not reproduce forever. As a scientific study such as Dr Shimek does lasting a few months to a couple of years it sounds great, but some of our reefs are decades old and the scientific studys fall short.
I also believe that a DSB works great for a few years then gradually ceases to function. (I used one in the 70s)
I can offer you the proof that I know as a scientist you need. Out of the 20,000 or so people on here and other forums, I don't think you will find more than 2 DSBs older than ten years old that are still functioning. There have been tens of thousands of them set up. I of course am not a researcher or scientist and I am sure you can quote vastly more scientific fact than I can. I am rather jealous of that and have great respect of scientists and am in no way trying to contradict your post.
As I said, I am glad you joined, we like brains here so again, welcome.

Thank you for your kind reply for someone so arrogant to interject on some old fogies.

I know there are limitations to DSB's and I have already decided that I'd like my second tank to not exclude the shrimps and hermits.

My primary draw to DSB's, other than the fact that I deeply respect Dr. Shimek's approach, is it offers an opportunity to observe ecolological dynamics and teach my daughter about it.

Now concerning the longevity of a DSB, I believe the un-scientific survey you mentioned has bias. That finding of bias is based on some observations:

That is the vast majority do not opperate a DSB the way Dr. Shimek advocates.

For example even on Dr. Shimek's own forum, questions are frequently answered with (remove X species that is a major predator of DSB beneficial creatures)

I believe this is because most people are not scientifically minded and don't appreciate the complexities of the ecological interactions.
Also LFS staff and many forum posts regurgitate non-fact statements like Hermit Crabs are herbivores. IME is a dirty word IMO I really like that Dr. Shimek has research papers on most any creature in our tanks and can tell me without guessing who eats what. However I will acknowledge that his papers are not presented in a manner that's very digestable to most.

All this being said. I have found much evidence of people having long term success when they follow the advice of Dr. Shimek. This most definitely includes recharging to avoid extinctions, proper depth and substrate particle size, proper footprint, proper LR placement, and knowledgeably excluding predators.

Thanks again for your welcome and glad to be here.

JD

 

[Paul B]

That is true about re charging to avoid extinctions, I myself add "creatures" and bacteria from the sea
throughout the year. Of course I run a very slow running reverse UG filter, (state of the art in 1973 :lol I doubt three people on here run one.
The one other problem I have with DSBs is that they can not be maintained and anything that has no means to be maintained will have problems.
Again, not a scientific experiment but if you have ever taken apart an old tank with sand in it (a tank 5 or 10 years old) that sand will have become compacted to the point of almost being concrete. The detritus, decayed crustacean shells, mud, dead bacteria etc. gradually fills the spaces between the sand grains and if you punctured such a tank it would barely leak because water can't penetrate. If water can not penetrate, nor can bacteria or chemical processes.
You would probably know about that better than I do but I have witnessed this a few times.

I believe this is because most people are not scientifically minded and don't appreciate the complexities of the ecological interactions.

This is probably true as this is a hobby and not a scientific forum. But some of us do understand the complexities of ecological interactions, I myself have dove with just about every animal commonly offered for sale to hobbiests.
There is vast amounts of information out there but as you said, most of it is inuendo's, suppositions or rumors. Someone states that they cured ich with a cleaner shrimp and eventually it is taken as fact by many people while in reality it is rediculous. But you will never convince people of that.
When I kept moorish Idols I, like everyone else had miserable luck, but then I went to the South Pacific to spend some time with them in their habitat and learned many of their secrets, now I have much better luck with them. If I relied on written works by people who never dove, I would still be trying un successfully to keep them.
I love to read but unfortunately, after spending so many years in the hobby, I have read all of the information that I would consider useful to me. Now I learn by spending time with the animals and keeping them.
I am by far not the most successful hobbiest on these forums and I have lost numerous animals over the years but in my defense, there was no information at all when I started.
As for the good Dr. I do respect scientific research and we would not know as much as we do with out it but it has limits and eventually we need to get into the water, get our feet wet and spend time with these animals, not as a tourist but as someone with a lot of time to just lay on the big DSB of the sea bottom and observe these things.
If you look through these forums you will see some beautiful tanks, but besides the beauty we should take the age of the system into consideration. If we take twenty or thirty thousand dollars like some people do, we can make fantastic looking systems. But if it lasts three or five years then crashes, is that a really good system? If the fish live five or six years is that ok? Most of our animals should live 15 or 20 years. If they do, then we have succeeded.
I know I am rambling, I am old so I am allowed to.
Anyway Longfellowship, I am very glad you joined and although this is a New to the Hobby forum so we must be driving the Noobs crazy.
I don't like to give advice to Noobs because I like RUGFs, mud from the sea along with all sorts of other things that people tell me I can't and should not do :rolleye1:
So take care and it has been a pleasure tonight.
Paul
PS.

is it offers an opportunity to observe ecolological dynamics and teach my daughter about it.

For that I got my Daughter certified to dive at age 13

 

[EdKruzel]

JD,
Welcome, glad to have you and your scientific background on board for this subject.

EC,
I've seen numerous sterile systems; dry or foam rock, dry sand with a bacterial additive or old school damsel cycle and within no more than 6mths they became a disaster. Every one of them was broken down.

As to what I'd consider a plague, has more to do with common sense, observation and experience. If while the lights are on there are more pods visible than cockroaches in a NY City diner, you may have a problem. If you have more bristle worms protruding from every crack and crevice than tinsel on a Christmas tree, you may have a problem. If you have a blanket of Red Cynobacteria that looks like a room in the Elvis mansion, you may have a problem. They are all vital components to a healthy system in certain amounts.

PlanB,
I would highly recommend any labeled "sand sifter" be excluded. I have a lot of years (a few short of Paul's) and would still hesitate an attempt to balance predator to prey ratios. In larger tanks there are more possibilities to add smaller gobies such as some shrimp gobies or smaller. Many of these will eat from the water column and do very little movement of the substrate beyond digging a burrow. And then some are master contractors, so it's a gamble that may be very costly. I did have a small Barber Pole goby (S. nematodes) in one of my reef tanks. I acclimated it and added it to the tank. It darted to the back out of sight and after a few days I wrote it off as dead. Three or four years later I bought a new house and when we were dismantling the tank for the move I found Mr. Barber Pole alive and well in the back corner. Apparently it found a large snail shell, moved in and kept to itself. That was an SPS and clam tank that was teaming with fauna.

 

[elegance coral]

Has anyone looked at the sand beds and rock pictured in Shemik's article? Most of these structures are calcium carbonate. Calcium carbonate is white. There isn't a white speck to be found in those pictures. That's because the calcium carbonate has been stained through algae growth and the rot and decay that plaques his systems.

This approach ignores the elephant in the room. Keep people occupied with the tiny processes that are true by themselves, and they won't see the big picture that changes everything. Life is possible on this planet due to a nutrient cycle that we all play a roll in. In our systems, this cycle can be thought of very simply. We add organic matter as food on a regular basis. A portion of this food ends up in the sand as uneaten food, poo, and dead animal, plant, and microbial tissue. These are all solid particles. As long as they remain solid particles the nutrients they contain, like phosphorus and nitrogen, can not cause problems in our systems. Therefore, if we can remove these particle while they are still in solid form, we've actually accomplished something. If they remain in the sand bed, mother nature will do what she does with dead organic matter. She turns it into liquid fertilizer. The process that take place in a Shemik sand bed are the same processes that take place in a compost pile. The organisms doing the work may be different, but the job they do is exactly the same. If we are trying to control nutrients that impede calcification and cause problem algae to grow, having a compost pile on the bottom of the tank is counter productive.

He claims that these nutrients will be converted into animals tissue like pods and worms. This is true, but the net benefit from this process is about zero. Food supplies and space govern populations. The population of "infauna" will reach an equilibrium with the food and space available in the system. In a healthy, stable, and mature system these populations will remain relatively constant. Even if there is a bloom of organisms, there will be an offsetting crash that fallows. The system will only be able to support a given number of infauna. As organisms grow and convert nutrients into tissue, there is an offsetting death rate among the organisms that releases these nutrients back into the system. The only way to have a net reduction of free nutrients in the system through this process, is if the population was in a constant state of growth. It is impossible for this to happen in our systems, or in nature. So, who cares if nutrients are converted into infauna tissue if the process doesn't reduce the nutrients? The article surly leads the reader to believe that nutrients are reduced through this precess, even though they absolutely are not.

 

[tmz]

It is obvious, in my opinion, that nutrients( organic carbon/ C. nitrogen/N and phosphorous/P) not coverted to living tissue mass are expelled as waste. But bacterial strains reduce the waste further and further. If the environs are right and the CNP are available in useful proportions for the complete anaerobic digestion process, bacteria and perhaps other prokaryotes will use every bit of nitrogen,phosphorous and organic carbon as well as other things ,leaving only precipitants which wont redissolve unless higher acidic conditions occur, ie ph drops significantly..

The infuana are needed,imo,to keep deep sand beds channeled enabling an adequate flow of water carrying all 3 nutrients(C,N,P) for the facultative heterotrophic bacteria to consume and/ or respire as they do with some of the NO3.
.
It's not so much about the sand critters role as detriavores ,as I think of it , as it is as sand sifters and water movers. It's more about the physics of water movement and the biology of the bacteria engaged in anaerobic digestion with the sand critters playing an important role keeping the food and energy line open for the bacteria The bacteria take nurtrients out of the water or from particulate matter and convert some of the inorganic nutrients( NO3, PO4 for example) back to organic forms as they consume them. Some of these organics are exportable by skimming and or granulated activated carbon.

Advective flow and diffusion alone aren't strong enough to generate the water turnover needed for hypoxic,ie non anoxic , conditions with adequate nutrients(dissolved organic carbon, PO4 and NO3) to support the bacteria in a deep sand bed if the bed is clogged or packed.Infauna can help keep channels open.

If the bacterial populations performing anaerobic digestion are properly maintained in terms of the nutrients they need and oxygen or nitrate to use for energy , at the end of their anaerobic digestion cascades most detritus(particulate organics) and dissolved organics will be mineralized .
Maintaining a deep bed with just the right water movement through it ,ie low oxygen but not anoxic, is easier said than done. If a deep sand bed is the choice for the tank then replenishing infauna and some of the clogged sand periodically can extend the life of the bed; help it support denitrifying bacteria in the deeper areas ,and; avoid anoxic zones (no oxygen and no nitrate) It's worth noting that if some organic carbon gets into anoxic areas , sulfate reducing bacteria will thrive producing sufides and toxic hydrogen sulfide as a by product. So improperly maintained beds can be dangerous to the animals in the tank.
There are other choices including; shallow beds, bare bottom tanks ,etc.
but deep beds are preferred by many and can do well for at least several years with some replenishments.FWIW, mine lasted more than 7yrs and I could have done better with it. I now prefer shallower beds for the beachy aesthetics, with deeper pools of sand for some of the fish that need them for burying.

Personally when it comes to empiricism vs science, aka experienced anecdotal observation vs information from more abstract scientific methods and experiments , I think they all have value in helping us grow beautiful reefs suited to our personal choices. I like to know how things happen but the complexity of the biology , chemistry and physics involved makes that hard to do and definative answers are too few.
The successes and failures of fellow hobbyist give very good clues particulary if you put a little science to your interpretation and learn how to sort the wheat from the chaff.

 

[Paul B]

Nice posts guys.
I especially like this analogy

If while the lights are on there are more pods visible than cockroaches in a NY City diner, you may have a problem. If you have more bristle worms protruding from every crack and crevice than tinsel on a Christmas tree, you may have a problem. If you have a blanket of Red Cynobacteria that looks like a room in the Elvis mansion,

 

[longfellowship]

Personally when it comes to empiricism vs science, aka experienced anecdotal observation vs information from more abstract scientific methods and experiments , I think they all have value in helping us grow beautiful reefs suited to our personal choices. I like to know how things happen but the complexity of the biology , chemistry and physics involved makes that hard to do and definative answers are too few.
The successes and failures of fellow hobbyist give very good clues particulary if you put a little science to your interpretation and learn how to sort the wheat from the chaff.

Empiricism (theory of knowledge that asserts that knowledge arises from evidence gathered via sense experience) is a fundamental foundation of science. All applied sciences rely on senses to gather data. I don't think Dr. Shimek relies on abstract scientific methods and experiments either. Abstract scientific methods and experiments would be taking a theoretical model approach and running a bunch of numbers and equations and bringing them out as facts. To be sure ecology does have such models as a starting point, but they are only a starting point because it would take more supercomputers than exist in this world to compile a complex enough model and it would still fail.

What is Dr. Shimek's approach?

The scientific method applied to reef tanks should start with a large understanding of the way it works in nature, check. Care should then be taken to draw out what differences there are in nature vs. the tank and in doing so attempt to minimize those differences, check. The differences that cannot be eliminated then need to be accounted for, check. After accounting for these differences care should be taken to keep compiling evidence to support and improve the reef keeping method, check.

I do understand what your saying though and I agree that experiences should not be thrown out. I prefer to draw upon the experiences of unbiased individuals. Since this is not possible I try to know what bias there is by knowing how they have made their decisions. The closer that decision making process is to the scientific method the more I trust them.

If anyone has had success with any method of reef keeping then I would strongly consider their experience and knowledge on that method. I cannot consider failure with a given method something I want to draw knowledge from, unless you know for certain what went wrong (which is very difficult for the layman to ascertain). I also can't consider statements along the lines of "all my friends and everyone I know has failed at this." Because for all I know everyone is doing the exact same thing wrong.

So to put it simply, in my case I will listen and draw on the personal experience of those who have had long term success with a DSB (there are more than three). I will also listen and draw on the knowledge of those who have failed at DSB's if they can tell me what they learned from their experience other than "DSB's suck."

JD

 

[tmz]

I read and reference Dr. Shimek's excellent work and learn from it but don't feel compelled to follow any particular method nor do I consider a 4 inch bed of sand in a tank with rock piled on it somehow more natural than other methods. I do like deep sand beds aesthetically and for the fish and anemones that benefit from them. However,I think they have significant limits and may not be the right one for everyone .
I think claims of ease for sandbed maintenance long term are overstated. Indeed not much is written on exactly how to keep them going . Often neglected beds lead to toxic tanks long term. I've read a myriad of accounts of deep bed tank crashes after 3 few to 5 years. I simply have not found many that have been maintained for the long haul. My own experience supports the notion that they have a limited useful life .
Not only do they stop reducing nitrate ; I fret they may release everything else(phosphate, carbon , etc) that has been stored in the organic material in them and perhaps even some precipitated or organically bound metals will release. Anoxia often occurs in neglected beds with hydrogen sulfide production. .
Keeping them fresh with infauna and new sand grains is not easy, ime.

Denitrification can be accomplished quite easily with only an inch or two of sand or even in a bare bottom tank.Current knowledge regarding denitrification in shallow substrate or even within the bacterial mulm itself make it less necessary to rely on deep sand beds than in the past and lead one to ask: Why do I need 4 inches of sand that I must keep live and periodically replace without disturbing the bed and risking releasing some toxic substance.?

 

[Paul B]

in my case I will listen and draw on the personal experience of those who have had long term success with a DSB (there are more than three).

OK maybe 4.
Is there anyone on this forum that has a still running DSB for longer than 10 years?
I am curious and would like to know.
And I would also like to know who has had a problem with DSBs.
I am also curious about that. I know this forum does not encompass everyone on earth with a reef tank but it is the largest forum of it's kind and may put some incite into this discussion.
Paul

 

[Scopus Tang]

Very interesting read (haven't yet read it all; started at the beginning, skipped to end and started reading it backwards). Had to stop reading as I have a few questions.

I won't claim to have been keeping reefs for nearly as long as most of you who are frequent posters (at least towards the end of the thread), however I have been keeping reefs for quite awhile. I got my start back in the day when we used to believe that it was best practice to remove all the dead coral and rock from the tank and bleach it white on a monthly basis. Nuff said.

My particular question at this point (and I apologize if it was previously answered somewhere deep inside the thread that I haven't gotten to yet) has to do with the production of the "toxic gases" within the DSB. Its always been my personal opinion that the need for 4" to 6" of sand was provided as more of a safeguard against the impulse buyer and eager beaver aquarist. While 2" to 3" may provide enough SB for removal of nitrates, the likelyhood of the aquarist or burrowing fish disturbing the sandbed enough to release the toxic gases is greatly increased, and IMO is one of the great contributers to the "case" of the crashing DSB. With 6" of sand, with the exception of a few of most active burrowers, it is nearly impossible to disturb the sand to that depth.

I also find the discussion in regards to flow slowing as the bed clumps to be interesting, but need to do some more research before I post any thoughts or comments.

Interestingly, our community is a little different from the norm. I don't believe that anyone in the reefing community here (at least to my knowledge) has a bare bottom or SSB. Every tank I know of has an internal DSB; and certainly there are problems, but I would argue that most are due to a lack of maintanence. I'll have to do some calculations on my oldest tank, which I believe is somewhere around the 10 year mark.

 

[longfellowship]

To each his own and I'm perfectly happy to admit I'm wrong if my sand bed fails after several years.

I don't feel compelled to follow any one person either, but for a newbie like me I like to know his opinion on a subject matter. I'm sure I'll adjust some things along the way, because even Dr. Shimek has bias as he'll admit. I definitely use other sources especially since he's not always clear. I respect him for much more than his opinion on sand beds. I appreciate his researched position on Strontium and Coral feeding to name a couple.

His documentation is a Godsend for someone like me who doesn't have much experience, but can't stand the stupidity of everyone everywhere throwing their casual observations and opinion around as fact. I would not have bothered to post if I had not felt like he was being greatly disrespected. I believe the innacurate statement that got me going was something about the physics of pushing nutrients around and the way the world works. I've already forgotten who the poster was on that so its not personal, but that statement showed a very poor understanding of nature as a whole.

I do know that Dr. Shimek will be the first to admit that DSB's aren't for everyone and not to do it if your not going to do it right.

I simply want my first tank to model an approach I respect. No offense, but if there was anyone out there that had garnered my respect like he has and touted some other reefkeeping model I would be doing that method. But he's about 100 times more knowledgeable and disciplined in his approach of not commenting outside of his researched knowledge base than anyone else I've encountered.

Someone who is as smart as him, yet freely admits "that hasn't been studied" or "I don't know". Communicates to my mind a respect for the authority of true knowledge that I can't help but follow. Guessing and ill-gotten conclusions are sworn enemies of knowledge. Based on all that I have seen out there, this hobby could use more Dr. Shimeks.

JD

 

[Paul B]

Longfellowship, get used to things like this

but can't stand the stupidity of everyone everywhere throwing their casual observations and opinion around as fact.

Remember this is the Noob forum and I mean no disrespect to them but I think that when someone does not have a lot of experience and they experience something that is new to them they will take it as fact even though there may be other factors involved or if they hear that something works for someone, they may assume it works for everyone all the time.
On these forums you will read many theories on things like ich, hair algae, cyanobacteria, nitrate reduction, substraits, etc. The problem is that this is not an exact science, there are too many variables and almost all of the "cures" for these problems will work in someone's tank at some point. Unfortunately, many of these "malady's" disappear on their own and the aquarist may feel that the $2.00 1/2" hermit crab ate all the hair algae in his 300 gallon tank or the cleaner shrimp cured all the ich.
I used to jump in on those discussions but I have found it usually a waste of time. There are just too many people entering the hobby and you could make it a full time job.
Not that I am the God of fish tanks but after 55 years of having them and killing hoards of fish, I have learned of a plethora of things that don't work.
Of course, I run a reverse UG filter so even I would not listen to me :crazy1:

 

[elegance coral]

OK maybe 4.
Is there anyone on this forum that has a still running DSB for longer than 10 years?
I am curious and would like to know.
And I would also like to know who has had a problem with DSBs.
I am also curious about that. I know this forum does not encompass everyone on earth with a reef tank but it is the largest forum of it's kind and may put some incite into this discussion.
Paul

I just shut down my DSB a few months ago. It was in use for just shy of 20 years. I still have the sand, but it's outside in one of those small prefabed ponds, like you get from Lowe's. I broke down that system when I moved. The sand is still white and relatively clean. Never had a problem with it. Naturally, I didn't run it according to Shemik's nonsense though.

 

[longfellowship]

Longfellowship, get used to things like this

I am very used to it:spin2: and I usually have the self control to stay out of it. Just a pet peeve and I probably hadn't had my weekly fill of debate.

 

[Scopus Tang]

Not that I am the God of fish tanks but after 55 years of having them and killing hoards of fish, I have learned of a plethora of things that don't work.
Of course, I run a reverse UG filter so even I would not listen to me :crazy1:

LOL; we shut down our last UG filter system only a couple of years ago.

 

[elegance coral]

I've already forgotten who the poster was on that so its not personal,

Ummmmm...... That would have been me.:wavehand:

Please don't take this personally. My only goal Is to help hobbyists care for these animals so that fewer will needlessly die. I do have a little piece of advice though.

His documentation is a Godsend for someone like me who doesn't have much experiencep

With all due respect, it will be next to impossible for you to determine who's documentation is a Godsend, until you have quite a bit of experience. This hobby is plagued with misinformation and half truths. Especially from some of the most popular authors and speakers we have. Your only hope to truly understand what's going on is to do the research for yourself. As a "scientist" you should have access to known scientific fact and studies.

I would not have bothered to post if I had not felt like he was being greatly disrespected.

I don't know the man. I mean him no more disrespect than I do you. My problem isn't with him. It is with an article written by him that causes hobbyists to keep animals in poor conditions until they die.

I believe the innacurate statement that got me going was something about the physics of pushing nutrients around and the way the world works.

As a self proclaimed "scientist" you must understand how meaningless this statement is. If what I wrote is "inaccurate" then show how it is inaccurate. Anyone can say that someone else is wrong. It doesn't mean anything unless you can show how that person is wrong. I have stated that Shemik's views on sand beds is wrong. I've pointed out flaws in his theory, explained why they don't work like he claims, and gave examples of what truly takes place when his methods are used. It would be meaningless if I said he was wrong just because I said so.

but that statement showed a very poor understanding of nature as a whole.

Again. Show me how. I've been studying nature as a whole all my life. There isn't a subject that I know better.

I do know that Dr. Shimek will be the first to admit that DSB's aren't for everyone and not to do it if your not going to do it right.

All that does is enable him to blame the hobbyists when his methods fail. Make the method as complicated as possible, and it's easy to find something the hobbyist did wrong.