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

[power boat jim]

Originally Posted by Dan_P

The simple answer is yes, but the "nitrogen cycle" is more complex than we are taught. Not all nitrogen leaves right away nor is it all converted to nitrogen gas. In fact, nitrogen is being recycled

Ammonia is consumed by algae and bacteria to produce biomass, growth. It is also an energy source for some bacteria in oxygenated environments resulting in nitrite and nitrate. These chemical species in turn can be consumed and reduced back to ammonia to make biomass or they can be used by some bacteria in low oxygen environments as a oxidizer which converts them to nitrogen gas. Everywhere that biomass is produced, it also is dies and decomposes, producing ammonia which journeys through the various channels.

Skimming removes some nitrogen containing compounds as does GAC, so, some nitrogen is exported this way. Harvesting macro algae is another way nitrogen is removed from the system.


Dosing carbon can alter denitrification versus biomass pathways.

At any given time, the aquarium is using a portion of nitrogen to increase biomass and a portion is being exported as nitrogen gas or as an organic compound.

This was the process I was more or less familiar with. I thought maybe I missed something when it was posted that the end result was hydrogen. For our purposes the process has always ended as N2.

[tmz]

Nitrogen doesn't all end as nitrate reduced to N2,however. There are at least 3 major known pathways for bound nitrogen in a reeftank:

autotrophic via the 2 step nitrification and denitrification processes where only some; not all of the N from reduced NO3 forms N2;

photoautotrophic via consumption of the nitrogen by algae and removal by harvesting and other photosynthetic organisms;and

Heterotrophic nitrogen reduction via assimilation by heterotrophic bacteria directly from ammonia in a one step process when organic carbon is available for heterotrophic bacteria to use as it is in most reef tanks at least for some of the nitrogen;more so in those where organic carbon like vodka and and vinegar are dosed :
The reaction is :
Ammonia + organic C + bicarbonate +oxygen ----> bacterial mass + water + C02. In this process there is no ammonia oxidation nor any nitite or nitrate formed an no N2. The bacteria are exportable via skimming.

I don't think it can be said that N2 is the majority of the export in general terms.

For those interested in more detail more on this reaction and an overview of nitrogen removal pathways see here:
http://ag.arizona.edu/azaqua/ista/IS...%20Ebeling.pdf

[Jay_R]

Originally Posted by power boat jim

This was the process I was more or less familiar with. I thought maybe I missed something when it was posted that the end result was hydrogen. For our purposes the process has always ended as N2.

Apologies.. My Bad. I'll read my posts back before hitting 'submit' in future

Maybe a more pertinent question would be 'is a DSB necessary'?

For my 55g set up with sump, the answer is IMO most definitely NO. In fact if i had a 200g system, I'd still not have a DSB as I don't feel it would bring any value to the upkeep of the tank that I couldn't deal with via other nitrate / waste removal methods. ( Skimming, Carbon dosing & Water Changes ).

A tank is an eco system, which evolves over time. I believe we just need to monitor the balance, and step in when something is out of sync.

[Dan_P]

Originally Posted by Jay_R

Maybe a more pertinent question would be 'is a DSB necessary'?

For my 55g set up with sump, the answer is IMO most definitely NO. In fact if i had a 200g system, I'd still not have a DSB as I don't feel it would bring any value to the upkeep of the tank that I couldn't deal with via other nitrate / waste removal methods. ( Skimming, Carbon dosing & Water Changes ).

A tank is an eco system, which evolves over time. I believe we just need to monitor the balance, and step in when something is out of sync.

I just reread Shimek's article on deep sand beds in Advanced Aquarist. The author makes some good points about deep sand beds along with some that I felt were pretty big leaps of faith, which is why some readers get a whiff of snake oil. I was not convinced by the article that a deep sand bed is necessary for a successful reef or fish only aquarium.

Your notion of the aquarium as evolving ecosystem that needs constant monitoring seem like the right approach.

Do you have any substrate?

[tmz]

Maybe a more pertinent question would be 'is a DSB necessary'?

There is a lot of discussion on that earlier in the thread( see posts nos. 250 to 350).

IMO, deep sand beds are not necessary ;nor inherently harmful when maintained. They can be fun for those who like the sand critters and microfauna they afford and are necessary for certain animals one may choose to keep like certain anemones, burying fish (some wrasses, jawfish etc) certain inverts like pistol shrimp , nausarius snails etc.



From my post #259


I've used and use shallow sand, deep sand and bare bottoms. There is no scientific reason of which I am aware to favor one over the other; they all require maintenance.
It is more of an aesthetic choice.
If you like the look of sand use it and clean it periodically,replenish some with new fauna bearing sand from time to time and it should do fine for a very long time . If you want to keep critters that need deep sand like certain wrasses and anemones ,using sand beds of appropriate depth for them is a necessity

Deep sand beds lost some of their allure a a biofilter , when I realized the bacteria performing denitrification are facultative heterotrophs. They live in the presence of oxygen and when they exhaust it in a given location they turn to nitrate for it facilitating the formation of N2 gas from some of the freed up N which exits the tank. If there is left over organic material and both oxygen and oxygen sourced from nitrate are exhausted,sulfate reducing bacteria take over.
This means denitrifying bacteria can do quite well in shallow sand or even on bare surfaces . They even create hypoxic conditions in their mulm where anaerobic activity occurs;ie, using the NO3 for oxygen. So, denitrification via assimilation of dissolved nitrogen as these bacteria grow and nitrate reduction to N and N2 occurs in the top half inch or so of the bed. Not much happens down deep for denitrification since these heterotrophic bacteria need a source of oxygen organic carbon, nitrogen and phosphate to grow and not much moves down there via diffusion, a relatively weak force or even advection a bit stronger but still inadequate force. Not much organic carbon,oxygen, nitrogen or phosphate will get down there fast enough to encourage much deitrification; nor much worry about sulfate reducing bacteria taking over and producing H2S since the sufat reducers need the organics too. In fact ,ime, you can find just as much evidence(black sufides) of anoxia and sufate reduction activity in shallow beds of an inch or so asanywhere else.

Overall, a shallow bed reduces nitrate a about the same rate as a deep one since the action is near the top where the nutrients are. Thus , the choice about a sand bed is more a preference than a case of a good method vs. a bad one,imo

[Jay_R]

Originally Posted by Dan_P

Do you have any substrate?

I have circa 1.5" - 2" ( A little higher in areas due to my Goby - and for my Wrasse) in my DT ( As my in Avatar ), but I have a couple of Nassarius snails who move things about, and a Diamond Watchman Goby who's life's mission is to constantly rearrange my sand bed.

Just to help things along, once a month, i'll use the handle end of my scrapper to stir up the sand and get as much muck out and into the water column. I've done this from day 1, so the risk of disturbing 'old' waste is non existent.

My sump is bare bottom as below..

http://www.reefcentral.com/forums/at...3&d=1434115123

[Dan_P]

Originally Posted by tmz

...when I realized the bacteria performing denitrification are facultative heterotrophs.

Did you perform DNA testing or metabolism studies to determine this?

[billsreef]

Originally Posted by Paul B

As natural as our bald heads

I'm pretty sure our bald heads are more natural than glass boxes

How do you know fishare not scared of PVC.

Observation I've yet to see a fish behave differently around a collection of PVC pipe fittings than they do rock in a tank. Currently have a puffer and scorpion fish in QT with PVC fittings, they aren't the least scared. Well the prey for the scorpion fish might be bit scared when they discover the scorpion fishing is hiding in that PVC

I try to forget everything

There is a word for that

DSBs make me sad and give me gas

Just blame the dog

Yes, but in the sea and in my tank, they don't affect them. In quarantined tanks parasites would kill everything

If the parasites kill everything in a quarantined tank, your doing it wrong. The idea is to kill the parasites and end up with clean and healthy fish. I do that all time, and my fish live a good long time, spawning and all

But Bill, I still love you and enjoy these talks. It is cold and raining here now so I am jealous of Floridians.

Nice and warm, high 80's and sunny

[tmz]

Originally Posted by Dan_P

Did you perform DNA testing or metabolism studies to determine this?

No, I don't have the skill or equipment to do that. There are many sources out there if you want to research further:

These links may help as a start:

https://en.wikipedia.org/wiki/Denitrifying_bacteria

http://www.selba.org/EngTaster/Ecolo...ification.html

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1448990/

[Aquarist007]

Great discussion as always.
I have learned that what works for one tank might not work with another.
Learning the how's for each method of filtration one might use is essential
The other key to their use is observation and measurement.
In the number of tanks I look after methods could vary from using a variety of methods to doing nothing other then using a skimmer.
Relative to this discussion on the depth of a sand bed it's hard to tell someone else to use it or not to use it if their system is healthy and flourishing and misinformative to state your particular success or lack of success with a dsb as a reason for not using or implementing one

[Dan_P]

Originally Posted by tmz

No, I don't have the skill or equipment to do that. There are many sources out there if you want to research further:

These links may help as a start:

https://en.wikipedia.org/wiki/Denitrifying_bacteria

http://www.selba.org/EngTaster/Ecolo...ification.html

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1448990/

Thanks for the good read! These references went right into my research file. I am thinking, it won't be long before we will be able get DNA testing for our aquariums and bio filters.

[CStrickland]

Originally Posted by Dan_P

it won't be long before we will be able get DNA testing for our aquariums and bio filters.

this is gonna make for a awesome season of Muary Povich!
They can bring all the fry onstage to announce the daddy, and a fin-fight will ensue....

I mean "tanked" is somehow still on the air, so it's not so far fetched

[Giovanni]

In the past I would keep a 5 gallon bucket full of sand in my sump. I read a crash could happen when a DSB gets old. So once every 12 months I would place a second one in the sump, after one month I would remove the 1st bucket and repeat every year. The one month overlap allowed the second one to get established. I would flush the sand from the old bucket and allow it so dry and use it the next year. The smell that came from the sand at about 6 inches and deeper was amazingly horrible. This method worked for me very well and I never had nitrate issues. I never had a crash. I got out of the hobby for a couple years and did not go back to it when I got back in.

[Johnnycat]

Originally Posted by Giovanni

In the past I would keep a 5 gallon bucket full of sand in my sump. I read a crash could happen when a DSB gets old. So once every 12 months I would place a second one in the sump, after one month I would remove the 1st bucket and repeat every year. The one month overlap allowed the second one to get established. I would flush the sand from the old bucket and allow it so dry and use it the next year. The smell that came from the sand at about 6 inches and deeper was amazingly horrible. This method worked for me very well and I never had nitrate issues. I never had a crash. I got out of the hobby for a couple years and did not go back to it when I got back in.

Do you feel the remote DSB is responsible for the lack of nitrates...and if so, why not go back to it if it worked?

I'm asking because I'm intrigued with the remote DSB debate and I like the biochemistry behind the remote DSB. I'm considering using this with my next build.

[Giovanni]

I was taught that a DSB is a nitrate sink do to anaerobic bacteria in the deep part of the sand.

I had a much smaller system volume back then. When I came back to the hobby, I went big, 450 system volume, and I had more money to throw at my system and I so I tried biopelets, GFO, etc.. I recently down sized from a 330g display to a 180g display and have considered trying a DSB again. However, I would probably need 3 or 4 5g buckets and do not have room in my sump for that. So I will probably not go that way. Every system has its pros and cons. I feel DSB is low maintenance way but probably does not scale up well for large DT systems.

[Shawn O]

Wouldn't plumbing a couple of 30 gallon drums inline work for a RDSB?

[tmz]

It wouldn't do much beyond the first 1/2inch or so of depth in terms of dentrification. There just isn't enough force to move enough nutrients down for a significant effect.

[Giovanni]

Originally Posted by tmz

It wouldn't do much beyond the first 1/2inch or so of depth in terms of dentrification. There just isn't enough force to move enough nutrients down for a significant effect.

Do you have data to back this up?

[Giovanni]

Originally Posted by Shawn O

Wouldn't plumbing a couple of 30 gallon drums inline work for a RDSB?

I don't see why not. However moving that kind of weight around at maintenance time would be prohibitive for me.

[tmz]

Read the thread it's all in here including a number of studies. What data do you have?

[tmz]

Originally Posted by Giovanni

Do you have data to back this up?

Be courteous and read the thread and avoid a need for tedious repetiton for those who have read it already; it's all in here including a number of studies.

When claiming a benefit the onus for proof or at least a plausible explanation of the mechanisms goes with the claim . So :

What data do you have to support the notion that deep sand is a "nitrate sink".What does that mean? It doesn't sink in the sense that phosphate does. How does sand accomplish creating a "nitrate sink" in a bucket of deep sand? How does water move up and down to bring nutrients to dentirifying bacteria? What bacteria perform this function? How do they survive without organic carbon, oxygen, phosphate , bound nitrogen or other elements they need?


The smell that came from the sand at about 6 inches and deeper was amazingly horrible.

Do you think that smell was from a "nitrate sink"? I don't. Does anyone care to guess what it was?

[Giovanni]

Originally Posted by tmz

Be courteous and read the thread and avoid a need for tedious repetiton for those who have read it already; it's all in here including a number of studies.

When claiming a benefit the onus for proof or at least a plausible explanation of the mechanisms goes with the claim . So :

What data do you have to support the notion that deep sand is a "nitrate sink".What does that mean? It doesn't sink in the sense that phosphate does. How does sand accomplish creating a "nitrate sink" in a bucket of deep sand? How does water move up and down to bring nutrients to dentirifying bacteria? What bacteria perform this function? How do they survive without organic carbon, oxygen, phosphate , bound nitrogen or other elements they need?

Frankly I stopped reading when I got to back and forth bickering that bordered on personal attacks.

I simply wanted to educate myself as to your statement "It wouldn't do much beyond the first 1/2inch or so of depth in terms of gentrification. There just isn't enough force to move enough nutrients down for a significant effect." I understood that diffusion is what drove the nutrients down in the DSB, but that the deeper you go the O2 is consumed leading to the anaerobic conditions.

A simple link to the data would be great.

If you take exception with my posts, please just bash me in a PM and spare the rest of the community having to read it.

[Giovanni]

Originally Posted by tmz

Do you think that smell was from a "nitrate sink"? I don't. Does anyone care to guess what it was?

Having never smelled it, what do you think it was?

[tmz]

No bashing .
I simply disagree that deep buckets of sand are useful for dentirifcation and think it would be misguided for folks to go off filling buckets with sand and expecting nitrate to be sunk there. It's not sunk If you think otherwise explain it and answer the questions. Perhaps thinking about them may bring out something that hasn't been offered earlier.

An open response is necessary vs a pm.

I don't consider challenging a recommendation with which I disagree bashing ;it's just probing discussion and should be open not private to provide information for folks to make an informed decision regarding a particular method or recommendation.

Just read the thread and the studies therein to explore denitrification in terms of the bacteria, the nutrients and the fluid dynamics involved . An argumentative response to my post like "Do you have data to back that up?" would be fine if the thread wasn't full of information including studies already including some in the pages immediately preceding this one. It's there if you want it.
I disagree with the notion that a deep bucket of sand is going to reduce nitrate in any significant way with only diffusion as a force Diiffusion is slow and weak. Denitrifying bacteria are hetertrophic and facultative not obligate anaerobes as once thought. They need some flow to bring the nutrients they need to grow and denitrify in the process.. They do well with oxygen and engage in anaerobic reduction of nitrate even in their own mulm or very shallow areas when they exhaust the free oxygen provided the y have an ample supply of nutrients to sustain growth. .As noted on the preceding page posts 250 to 350 have a lot of information on this part of the discussion but there is lots more throughout the thread.

[Giovanni]

Originally Posted by tmz

I don't consider challenging a recommendation

I never recommended using a DSB. Pursuant the OP's original question "Are Deep Sand Beds, DSBs, dangerous to use in a marine aquarium" I simply shared that for years I had a DSB albeit remote, and never had issues. I explained why I used it back then because I figured someone would ask that next.

Peace Out