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Deep Sand Bed -- Anatomy & Terminology


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Undetectable nitrate concentration in a water sample is about as remarkable to me as a proper temperature, ph, or salinity reading...you don't need a DSB to achieve those either, and those parameters alone do not create success.

 

I like to see full tank shots that demonstrate how well these ideas work. I for one have always considered them a pain in the ass to keep in a tank with corals that demand high flow, and a sink for "gunk" to build up over time and decompose.

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Most often their purpose is for nitrate reduction, so that is this article's focus, but that is not their only purpose, nor is a DSB the only means for achieving that goal. Not everyone uses a DSB...

 

Thank you for reiterating. ;)

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  • 1 year later...

Today, I did the unthinkable. I've moved, and after much consternation, I've accepted the fact that there simply is no moving a DSB. After 5 years of cultivation... I had throw it out. :(

Good news! Even tho I hadn't done a water change in 5 months time, there were no bad smells, just the refreshing smell of the beach. No bad smells while digging thru the sandbed and not even a hint of H2S. In fact, everything about the sand was remarkably clean. No hard-panning and no organic gunk. This DSB could have easily gone another 5 years!

I attribute my good results almost entirely to a single factor, that in turn benefited a single type of organism: high-flow and spionid worms.

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  • 2 weeks later...

Today, I did the unthinkable. I've moved, and after much consternation, I've accepted the fact that there simply is no moving a DSB. After 5 years of cultivation... I had throw it out. :(

 

Good news! Even tho I hadn't done a water change in 5 months time, there were no bad smells, just the refreshing smell of the beach. No bad smells while digging thru the sandbed and not even a hint of H2S. In fact, everything about the sand was remarkably clean. No hard-panning and no organic gunk. This DSB could have easily gone another 5 years!

 

I attribute my good results almost entirely to a single factor, that in turn benefited a single type of organism: high-flow and spionid worms.

I'm not sure how far you were moving, and perhaps out of ignorance I also did the unthinkable! Last December I downsized from a 90g softie with a DSB, (set up in '06) to a 36g bowfront. I too hated to lose all the worms and beneficial creatures so I kept the same sand for the bottom 4" and just added new sugar sand on the top. I kept the sand wet, (and like your sand it was fresh smelling ) but I had to handle it twice because the new tank was going in the same place as the old tank and the 90 was just too heavy to move with 5" of wet sand in it. The transfer probably took 2-3 hrs for just the sand. Anyhow I expected die off and thought it might delay my cycle but it didn't. The tank stabilized in less than 2 weeks. I kept all my smaller fish, inverts and even added a crocea clam after the tank was running for a month and a half. Tank and inhabitants are doing great and my sandbed looks like the pictures you took of yours. If I look at the bottom of my sandbed from the inside of the cabinet it is smooth and white with maybe one critter track but nothing black or scary. If I'd read your thread first I might have been scared to do what I did but I guess ignorance is bliss!

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... I guess ignorance is bliss!

 

The reason a DSB can't be moved is because the anaerobic bacteria found in the hypoxic layer of the sandbed are very easily killed by oxygen. It is irrelevant if the sand remains wet. If you scooped it up, then the anaerobic bacteria have died. If you have not experienced significant die off, then your DSB may not have been a function DSB to begin with. You say it looks just like mine did, but you've given no photo. In short, what you are suggesting isn't possible. You can't move the sand without oxygenating the hypoxic layer and killing off the anaerobic bacteria, resulting in a non-functional DSB, at best.

 

No. There is no bliss to ignorance.

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The reason a DSB can't be moved is because the anaerobic bacteria found in the hypoxic layer of the sandbed are very easily killed by oxygen. It is irrelevant if the sand remains wet. If you scooped it up, then the anaerobic bacteria have died. If you have not experienced significant die off, then your DSB may not have been a function DSB to begin with. You say it looks just like mine did, but you've given no photo. In short, what you are suggesting isn't possible. You can't move the sand without oxygenating the hypoxic layer and killing off the anaerobic bacteria, resulting in a non-functional DSB, at best.

 

No. There is no bliss to ignorance.

Ok, I've been pondering what you said in your post and I was apparently making some wrong presuppositions. I figured anaerobic bacteria could begin again as they did when a tank is first started up. However if they all died and that's not possible, where do they come from in a new tank with a DSB? I'm also presupposing that if my tank does not have a functioning DSB that means it is not useful in reducing nitrates? However is it ok as at least a home for worms and pods? I don't want to tear down a stable thriving aquarium unless the DSB I have is dangerous? I don't have nitrates so maybe its ok that its not functioning? Any insight would be greatly appreciated. Thanks!

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I might not scap the tank yet. Bacteria are an amazing group and in a setting such as a dsb the bacterial community might reach a state of homeostasis given the right time and conditions (nutrient amounts, which nutrients are available and currently don't have another group ingesting them) once a bacterial community reaches that state it is hard to completely upset that balance as long as the conditions are returned to they were before.

Further more bacteria are genetically fluid so as long as some of them survived, as the bacteria from higher in the sand bed use the oxygen up the bacteria would change (two weeks would be a very impressive turn around however) to adapt to the environment and allow for the anarobic community to return to its homeostasis.

This is based on bacteria in general and just a thought on how it might be possible, but is very dependent on the original state of your particular dsb.

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  • 2 weeks later...
I might not scap the tank yet. Bacteria are an amazing group and in a setting such as a dsb the bacterial community might reach a state of homeostasis given the right time and conditions (nutrient amounts, which nutrients are available and currently don't have another group ingesting them) once a bacterial community reaches that state it is hard to completely upset that balance as long as the conditions are returned to they were before.

Further more bacteria are genetically fluid so as long as some of them survived, as the bacteria from higher in the sand bed use the oxygen up the bacteria would change (two weeks would be a very impressive turn around however) to adapt to the environment and allow for the anarobic community to return to its homeostasis.

This is based on bacteria in general and just a thought on how it might be possible, but is very dependent on the original state of your particular dsb.

I was curious about my nitrates and since my test was ancient I just bought a new one and tested. My nitrates are zero. All my parameters have been and are stable. I have 6 fish,(about 15") in a 36g so I feed moderately heavy so I am going to assume from what I am seeing that my sandbed is functioning. I can't bring myself to tear this tank down from what I see and what my gut tells me about my tank.

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I have moved a functioning Jaubert Plenumn 75G tank with a 6" DSB of coarse substrate. While it does not have as diverse a population of detrivores as sugar sand, the bacteria figured it out ad repopulated the tank.

 

With repespect to zero nitrates as proof that denitrification is happening in sand-bed ignores the uptake of nitrate by other consumer of nitrate like coral and macros.

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skimlessinseattle
I have moved a functioning Jaubert Plenumn 75G tank with a 6" DSB of coarse substrate. While it does not have as diverse a population of detrivores as sugar sand, the bacteria figured it out ad repopulated the tank.

With repespect to zero nitrates as proof that denitrification is happening in sand-bed ignores the uptake of nitrate by other consumer of nitrate like coral and macros.

Interesting point. I think it is very difficult to prove denitrification from that type of qualitative observation. I have a DSB on my frag system, and never register nitrates, although I cannot conclude from this that denitrification is at work in the sand bed. What I do see that strongly indicates the process is occuring is the release of bubbles from all over the sand bed. Again, this is a qualitative observation, but one that suggests denitrification. Interestingly enough, when i set up the DSB, I used dry sand, and only inocculated the top layer with some course sand from another tank. This thread states that by moving the DSB, it will be non-functioning due to the immediate death of hypoxic bacteria. While I agree that obligate anaerobes would likely perish in the transfer, facultative anaerobes would survive the transfer, and once back under appropriate conditions, resume their processes. My point being, the sand i used was non-functioning at one point, but as Subsea stated, the bacteria figured it out.
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I have moved a functioning Jaubert Plenumn 75G tank with a 6" DSB of coarse substrate. While it does not have as diverse a population of detrivores as sugar sand, the bacteria figured it out ad repopulated the tank.

With repespect to zero nitrates as proof that denitrification is happening in sand-bed ignores the uptake of nitrate by other consumer of nitrate like coral and macros.

Yes, you are correct. I can't assume the lack of nitrates is definitely a result of my DSB. I do have a crocea clam and large growing colonies of LPS coral that could very well be utilizing any nitrates that might be there. But I think regardless I am not going to tear this tank down and hope that the bacteria did figure it out.

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While I do not completely accept "microbial overlords; without bacteria, the reef ecosystem will collapse. I have been skimmer less for more than 20 years. It works for me.

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Is there somewhere online I can buy live sand that is actually LIVE? With worms and critters? I would like to set up a DSB in my next tank.

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skimlessinseattle
Is there somewhere online I can buy live sand that is actually LIVE? With worms and critters? I would like to set up a DSB in my next tank.
Yes, there are several sites. IPSF has a package with video on some of the critters, but I have no personal experience with it. Better option, and cheaper, would be to buy some from someone who already has an established sand bed.
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  • 2 weeks later...

If I remember from my microbiology lab class right, obligate anaerobes wont die just from short term exposure to air, but cant grow in the presence of oxygen. Kind of like taking Zoas out of water, yeah they arnt happy, and if you leave them out of water they will die, but they can have short term exposure. Then there are facultative anaerobes which couldn't care less about oxygen really and will grow in pretty much any conditions unless they are outcompeted for nutrients.

 

The proof being if it wasn't possible, you would never get obligate anaerobes in a DSB as when you lay down a sand bed in an aquarium you inherently either expose it to air or aerated water, both with oxygen present. The problem that I could see moving a DSB would rise from the hydrogen sulfide and other sulfide compounds getting mixed through the sand bed and into the water column.

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Nano sapiens

The first page shallow sand bed drawing is incomplete. A shallow 1-2" SB can act as an efficient nitrification AND denitrification substrate:

 

Sprung and Delbeek's 'The Reef Aquarium' series (Vol 3) has some well written and informative information regarding denitrification Pages 260 - 261 go into some detail on the subject:

 

"It has been shown that nitrification and denitrification occur in aerobic layers where they are termed coupled since the processes occur simultaneously, mediated by bacteria in close proximity. Here anoxic microsites provide habitat for anaereobic bacteria, while being surrounded by aerobic pore waters (Jenkins and Kemp, 1984). This is in contrast with the mental concept that the processes occur in separate aerobic and anaerobic zones."

 

Theoretically, any non-toxic substrate that contains 'micro-pores' should allow for the nitrification/denitrification process to proceed when water movement is present, but some substrates would be more suitable than others. The problem often encountered in reef tank aquaria is excessive material (detritus, bacterial films, etc.) that can drastically reduce the efficiency of the process.

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  • 1 year later...
stefalopod

I've got a five year old 6" DSB on my 10 gallon tall tank, and I'm trying to figure out what to do with it. I'm moving and starting up a 10 gal nuvo fusion. I don't think a DSB is an option unless I create steps to have a DSP toward the back and SSB toward the front. I know you can't really "move a DSB", but I definitely have lovely live bacteria colonies in there, and some of them might survive and propagate...

 

I wonder if any one has built DSB sections using LR as a mini-retaining wall before?

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