what is all of this dsb crash talk i read?

[hillrc91]

Originally posted by drtango
Richard-

I think it's important to note that nobody is disputing that DSB's "work" for a time, the length of time is in question. Mine worked fine for 3+ years, yours may work longer, depending on the animals you choose to keep.

My nitrates are unmeasurable with no DSB--lots of skimming, healthy live rock and thousands of gallons of water movement are enough in my heavily fed system--remove the organics before the bacterial cascade gets out of hand--why install a system to deal with something you don't need to keep in the first place?

Drtango,

I understand what your saying, and it's been echoed by many others. As I told Habib, I'll take the thing out immediately if I see conclusive evidence showing that DSB's are a ticking time bomb, so to speak. I'm not too proud to admit I'm wrong, if indeed I am. But at this particular time, I've talked to many who have never had a single issue, and have been running DSB's for over a decade. In a previous thread, I stated that all of the negativity surrounding DSB's gave me a moment of pause, but with a lump in my throat, I went ahead and did it, because the balance of the evidence seems to suggest that DSB's can be a successful tool in Nitrate management.

[Habib]

Originally posted by hillrc91
Habib,

My primary concern is the well being of my fish. If the DSB crash theory is true, and presented in a coherent manner, I WILL take my DSB out without a second thought. I'd literally do it today if I felt that there was a "clear and present danger." What I'd really like is for someone to tell me WHY it works long term for so many, and seemingly fails for others. I'd like Dr. Ron, Bob Fenner, Anthony Calfo, Bob Goemans, and some of the other giants of marina aquaria to state why DSB's never seem to give them any trouble.

Richard:

I tried to follow some DSB threads and have also actively searched for scientific publications. Besides that I am also an experienced hobbyist.

I have an opinion about DSB and my current opinion is that I would not advice anyone to use it.

I'm pretty sure that there are many tanks without problems using a DSB for many years. So I don't doubt that it can be in a tank without problems.

The problem I see is that it can act as a sink for substances which we not would like to get released back fast into the water column.

It will be more of a sink the more input of nutrients there is and the less is exported outside the tank by other fast methods such as skimming.

This can be different for each tank and even vary with time for the same tank (e.g. lack of maintanence)

Also, if Ron is correct and if I understood it correctly, one has to have a certain amount of organisms inside the bed in order to function properly. Now if that is correct how can one determine if there are enough organisms with the required diversity in the sandbed?

That's why I called a DSB a piece of equipment. For one tank it can be of importance and for the other the function of it is primarly taken over by other pieces of equipment even though there is a DSB present.

My concern is that the DSB can fail and it might not be evident that is failing or has alreday failed to function properly.

So basically I would like to ask is a DSB really important and if it is can it ever fail to function properly and if it can fail can we see it happen and do we have the methods and time to remove it or repair it without harming the tank.

[Bomber]

Originally posted by Randy Holmes-Farley
can you provide a link to an exact post that shows data supporting the idea that a sand bed lead to an actual crash of an actual reef tank?

I think this is the crux, so to speak.

For one thing, I'm not going to write grants or hand out money to someone for the specific purpose of studying aquariums. Why is that? Because there are literally millions of aquariums already in use - we call them MODELS.
In the process of studying these different environments there is a certain amount that is done "on site", the bulk of the work is done on dry land using MODELS.

[hillrc91]

gregt,

I'm tired of being immediately attacked so violently for presenting the positive aspects of DSB's, and lampooned as being an idiot for even attepting such a heresy. No one has said that bare bottom tanks or shallow sand beds are wrong, and that they too have their benefits, I just personally see the benefits the DSB is having on my nitrate level.

[Bomber]

Richard, you need to report those "immediate violent attacks" to a mod. That's unacceptable behavior around these parts.

You only have 29 posts, would you please point out exactly where you were attacked?

[Randy Holmes-Farley]

I guess that I'm the only one in the "cooling off period".

I can fix that.

Let's try later today.

[Randy Holmes-Farley]

OK, we're live again.

Instead of the inflammatory words like "crash", I think that perhaps this is a compromise statement that many of us could agree with:

"A sand bed will initially act as a sink for nutrients, both nitrogen and, to a smaller extent, phosphorus. That in itself is not a problem, and serves to keep the nutrient levels lower in the water column. After some period of time, the sand may begin to no longer be a sink for phosphorus. In some cases, about which we may debate the likelihood of it taking place in a typical reef aquarium, and under what conditions, the sand bed may even become a source of phosphorus. If the aquarium is unable to handle the phosphorus in other ways, and if it contains inhabitants susceptible to stress from elevated phosphorus (such as many calcifying corals and coralline algae), it may begin to decline in overall health."

[photobarry]

Why don't we just measure inputs and outputs to determine how much of what is staying in the tank? I think we first have to determine how much export (and of what) is taking place in different tank designs. Then we can look at where the excess is likely to end up and at what rate it will accumulate.

[Randy Holmes-Farley]

Knowing that P is staying in the tank doesn't say where. Sand, coral bodies, fish bodies....

[photobarry]

But it is a starting point. Determining if there is a small difference between import and export or a large difference would be a good thing to know. We can estimate how much fish, corals, and algae can incorporate. There must be studies out there that have analyzed the body composition of all those things.

I like to use cyano growth as an indication of excess phosphorous. Since cyano fixes it's own nitrogen, it is primarily limited by P. I yanked the sandbed in one of my tanks when the cyano was getting out of control and growing on the sandbed. The sandbed was still processing nitrate but the indications to me, was that it had stopped storing P and was slowly releasing it.

[Bomber]

Dang it, I told you I was going to lose every thing I typed and I did. LOL

I would like to resume the discussion then, but let's try to get some agreement on what we are at least talking about :

1. What is a "crash"?

When a system is no longer able to properly support the animals, plants, etc that it is required to support and/or designed to support.

2. What types of aquaria are being discussed?

All of them

3. Do folks believe that an increase in nutrients (phosphorus, I presume) would necessarily lead to a crash?

Hello, this thing on?

4. If 2 is a yes, under what circumstances? When there is no other phosphorus export mechanism? Or even when there ae other mechanisms (like macroalgae, iron oxide media, etc.)

I still can't believe people are putting rust in their tanks.

I know you know all about dilutions, you taught me. What has to happen in a main system in order for a remote system to remove something?
Keeping in mind that using these "other mechanisms" you will only be removing the most reactive form of phosphorus, water soluble, limiting phosphorus - what has to happen in marine environments in order to have water soluble phosphorus?

What would have to take place in a aquatic system in order to have something that's limiting available in it's most available, most reactive form?

Take ammonium for instance, how long does it hang around? Do you try and remove it in that state, or do you wait until it's incorporated/changed/saturated and leaks back into the system in another form, or ultimately as ammonium again?

[Randy Holmes-Farley]

But it is a starting point. Determining if there is a small difference between import and export or a large difference would be a good thing to know. We can estimate how much fish, corals, and algae can incorporate. There must be studies out there that have analyzed the body composition of all those things.


Since sand beds can be around for years, the amount that can possibly get bound into a sand bed is very small compared to what is put into my tank and what is taken out, for example.

[Bomber]

Originally posted by Randy Holmes-Farley
Knowing that P is staying in the tank doesn't say where. Sand, coral bodies, fish bodies....

That's where a knowledge of sulfur/sulfide reducing bacteria comes in handy.

[photobarry]

Originally posted by Randy Holmes-Farley

Since sand beds can be around for years, the amount that can possibly get bound into a sand bed is very small compared to what is put into my tank and what is taken out, for example.

I would tend to agree with that, but that leads us to what Bomber posted above regarding the different forms of P.

[Bomber]

Originally posted by Randy Holmes-Farley
Since sand beds can be around for years, the amount that can possibly get bound into a sand bed is very small compared to what is put into my tank and what is taken out, for example.

Nooooo

As long as you provide habitat and food, bacteria will multiply until they either run out of habitat or food. The tricky part with these guys is they don't let go of their food until they have to and provided that they have a habitat that's malable, they will create more habitat for themselves.

ie. They will move the anaerobic area of the sand bed closer to the top.

[photobarry]

Originally posted by Bomber
Nooooo

You are supposed to agree with me, now you are making me look bad!

That is one thing we haven't determined: How much P can possibly be stored in a dsb and what's the maximum rate of release.

[Bomber]

Originally posted by photobarry
You are supposed to agree with me, now you are making me look bad!

That is one thing we haven't determined: How much P can possibly be stored in a dsb and what's the maximum rate of release.

LOL you're the vent guy, you're supposed to know this.

P is manufactured in the aerobic, stored in the anaerobic. Bacterial turgor will move/push the anaerobic area up. When they run out of habitat - exposed to aerobic - they leak. It's actually a great battle zone, the anoxic/suboxic that is.

OH, nevermind. I just realized that where you work there is no aerobic zone or eutrophication.

[Guy]

Just a comment from the peanut gallery

Although I have not yet experienced the "reef tank wasting" effect I see associated with sand beds, I have seen quite a few tanks in the past 20 or so years that seem to stop thriving.

Sand beds are not the common theme among the tanks I've seen. I seem to remember that only about half had deep sand beds. I have noticed live rock in large quantity in every single one though.

Just food for thought.....

Guy <--- severly chemically challenged DSB owner

[photobarry]

Originally posted by Bomber
LOL you're the vent guy, you're supposed to know this.

OH, nevermind. I just realized that where you work there is no aerobic zone or eutrophication.

The places I work at get covered in lava every 10-15 years so we don't have to worry about that sort of stuff. We just have rock, water and bacteria. That simplifies things.

[Bomber]

Originally posted by Guy
Sand beds are not the common theme among the tanks I've seen. I seem to remember that only about half had deep sand beds. I have noticed live rock in large quantity in every single one though.

Guy, I'll try to field this one while Randy's thinking.

Dirt is dirt. Decomposing dirt is decomposing dirt.

Even BB tanks "crash" if you let them sit there and get dirty.


LOL Barry

[Guy]

Originally posted by Bomber
Even BB tanks "crash" if you let them sit there and get dirty.

Absolutely.

[gregt]

...and on the other side of the coin, even a bucket of sand and saltwater sitting in my backyard for 10 years could be described as a successful tank depending on your definition of success....

[Bomber]

We found a old Igloo cooler that must be 30 years old, still had salt water in it and a whole mess of marsh flies.
To the marsh flies it was a very successful 30 year old reef tank.

[Randy Holmes-Farley]

Aquacultural Engineering
Volume 27, Issue 3 , March 2003, Pages 159-176

Water quality and nutrient budget in closed shrimp (Penaeus monodon)
Dhirendra Prasad Thakurm4.cor*m4.cor*, mailto:dpthakur@hotmail.commailto:dpthakur@hotmail.com, a, b and C. Kwei Lina

Nutrient budget revealed that shrimp could assimilate only 23–31% nitrogen and 10–13% phosphorus of the total inputs. The major source of nutrient input was feed, shrimp feed accounted for 76–92% nitrogen and 70–91% phosphorus of the total inputs. The major sinks of nutrients were in the sediment, which accounted for 14–53% nitrogen and 39–67% phosphorus of the total inputs.

This closed/model/aquarium.



The article posted above that supposedly shows that aquaria can be harmed by sand beds only shows that phosphorus accumulates in sediment in a shrimp tank. Is that even sand, or just accumualted shrimp poop?

I don't dispute that phosphorus may accumulate in sand, if only inside of organisms living there.

But is there any data, even non aquarium data, showing it comes back out in greater amounts than it goes in? Or in some form that is more harmful than it went it?

It seems to me that there is a lot of speculation here to connect the dots between some aquaria that seem to stop thriving after a number of years, and the accumulation and potential release of phosphate.

[Bomber]

The article posted above that supposedly shows that aquaria can be harmed by sand beds only shows that phosphorus accumulates in sediment in a shrimp tank. Is that even sand, or just accumualted shrimp poop?

It clearly says sediment.

I don't dispute that phosphorus may accumulate in sand, if only inside of organisms living there.

But is there any data, even non aquarium data, showing it comes back out in greater amounts than it goes in? Or in some form that is more harmful than it went it?

It shows a input of 76-92% nitrogen with a sink of 14-53% nitrogen, depending on how well the denitrification process was working. A 70-91% input of P, 39-67% sink.

You must be really confused about this if you think it would come back out in great amounts than it goes in.
Even Frank's marine chemistry book talks about it accumulating "chemically", so you at least know that part.
Again diffusions. (I really wish you had read that thread and understood what you were reading so I don't have to keep repeating this over and over.) Say in your aquarium you have a constant low level of P - either due to inputs, or leaking, or both - that is kept at that level by bacteria in the sandbed accumulating it and acquiring new habitat.
When they run out of habitat, move the anaerobic area closer to the surface, two things happen. Incorporation is not as fast and leaking is faster. Rocks start wicking it up faster are you start to see cyano (P limited), derbesia, etc where they are the closest to the leak.
For one thing the rocks are no longer sitting in a aerobic/anoxic area.

We all know that aerobic decomposition is not efficient, it takes a much larger aerobic area supported by a much smaller anaerobic area. As you add more food - slowly if you want to - P - bacterial particulate detritus - etc - the anaerobic area has no place to go but up.

It seems to me that there is a lot of speculation here to connect the dots between some aquaria that seem to stop thriving after a number of years, and the accumulation and potential release of phosphate.

Gee I don't know, what do you think has happened when bays, lagoons, aquatic environments stop thriving after a number of years?

Can you make the stretch between what happens in the real world and what happens in the magic box?LOL (teasing)