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Denitrification


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#1
Mr. Fosi

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Over the last few days I've been reading some stuff about detitrification and ways to accomplish it. My reading has focused on DIY Remote Deep Sand Beds (RDSBs) and denitrator coils rather than the very pricey commercial sulpher/bioball/ceramic ring based systems. I have also done some reading on vodka and sugar dosing of systems to keep the nutrient level down, but that seems more like a band-aid than anything else.

What lead me to this reading was a desire to biologically control both NO3 and PO4 buildup in a cost-effective way, rather than do weekly waterchanges. Occasional waterchanges, of course, still being a necessity to replentish Ca, I, or other minerals in lieu of dosing. I did a search here at NR and the only thing I found that mentioned these methods in more than a passing comment was the NR link in this list.

http://www.marinelan...rts/report1.asp
http://www.nano-reef...0&hl=rdsb&st=20
http://reefcentral.c...25&pagenumber=1
http://www.reefcentr...denitrator coil
http://www.reefcentr...threadid=595109
http://www.reefcentr...25&pagenumber=2

I got oriented toward RDSBs and coils b/c I don't think that a conventional in-tank DSB is desirable in a nano tank, mostly because 1) the footprints of our tanks don't allow much surface area for material exchange, 2) we would have to give up valuable real estate to several inches of sand, and 3) many people don't keep their nanos running undisturbed long enough to really glean the benefit.

Initially, I liked the coil idea until I got into the nitty gritty of tuning them to make sure you weren't pumping NO2 or H2S back into your system. Add the fact that most of these systems are designed and built for much larger systems with extremely heavy bioloads (100-300ppm NO3 in many cases) and you get something that doesn't look like it is easily applicable to nanos.

On the converse, it seems that RDSBs might have an nano application. They are simple to construct, easy to maintain, and don't require tuning. Depending on the size, they also may not need much in-tank bioload to keep them running.

I have read about two different RDSB setups, both of which were employed in larger systems, usually with either a rubbermaid trashcan or a standard 5g bucket. Some people used silica play sand from HD/Lowes, some used sugar-sized aragonite, some used a mix, and all were successful to varying degrees.

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The topics of discussion here are: 1) Is biological denitrification worth trying for in a nano (6-55g)system? 2) Do you think that coils or RDSBs would have any real value in a nano system, or are they just one more gadget that we would have to muck around with? 3) Would a nano provide enough organic carbon to keep heterotrophic denitrifiers going or would you have to periodically dose methanol, EtOH, or sugar?
"Ocean: A body of water occupying about two-thirds of the world made for man - who has no gills." ~Ambrose Bierce

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#2
jafoca

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I too have read a bit of the RDSB discussion on RC. After reading that I wish I would have planned one into my system instead of a fuge or skimmer!

#3
MrAnderson

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In my opinion the simplest and most natural method for denitrification is live rock. If you have enough and it's healthy, you should never see nitrates in your tank. At all.

That being said, I do like the idea of the RDSB best of all the methods that I've heard for supplemental denitrification. If it's large enough you could theoretically really go way over traditional bioload limits.

As far as RDSB design, I don't really like the bucket idea. If your pumping water thru the bottom > up, you're not going to have a substantial anaerobic environment. If you run water over it, the bottom will get funky if the sand is too deep.

I was thinking of trying a custom acrylic tank, maybe 8-10" deep, but long, with maybe 4-6" of mature live sand. Run the water over at a rather high rate and let Bernoulli take care of the mild circulation needed deep down.
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#4
Mr. Fosi

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In my opinion the simplest and most natural method for denitrification is live rock. If you have enough and it's healthy, you should never see nitrates in your tank. At all.


What about a bioload that is large relative to volume, i.e. one perc in a 5.5g w/12lb LR? I only feed every 3-4 days and I have to do large-ish waterchanges to keep my NO3 down in the 5-10 mg/l range.

That being said, I do like the idea of the RDSB best of all the methods that I've heard for supplemental denitrification.


Why? Just the simplicity?

Run the water over at a rather high rate and let Bernoulli take care of the mild circulation needed deep down.


That is what was being suggested in the bucket RDSB thread at RC. They were talking about moving a lot of water through. Like 300+gph through the top 4-5" of open water above the sand in the bucket and using sponges on the outlet to keep sand from being washed out. The main reason they stated was to keep particulates from settling rather than circulation through the sand.

Edited by Mr. Fosi, 06 April 2006 - 07:44 AM.

"Ocean: A body of water occupying about two-thirds of the world made for man - who has no gills." ~Ambrose Bierce

Mr. Fosi's drilled 20H w/150W Sunpod *dismantled*
Mr. Fosi's Budget 20L *dismantled*
Mr. Fosi's 5 gallons of convention-defying madness *dismantled*

#5
MrAnderson

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Sorry I just glanced through the threads and your drawing. As far as your setup, it's probably a good idea.

As for the flow issue, you do need some form of mild circulation to keep a DSB healthy. As long as the O2 gets consumed before the water reaches deep it will be a very effective denitrifier. As for particulates settling, that's the food for the initial nitrogen cycle bacteria. Personally, I would probably stir in detritus rather than take it out. It would boost bug populations and be helpful in the long run.

But again, I can't read that thread right now, so take everything I say with a grain of salt.
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#6
Mr. Fosi

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As for particulates settling, that's the food for the initial nitrogen cycle bacteria. Personally, I would probably stir in detritus rather than take it out. It would boost bug populations and be helpful in the long run.


That is what I thought, but the people at RC don't think so. I didn't see a good reason for this and I am thinking of posting a question about it.

The origional questions stand:
1) Is biological denitrification worth trying for in a nano (6-55g) system?
2) Do you think that coils or RDSBs would have any real value in a nano system, or are they just one more gadget that we would have to muck around with?
3) Would a nano provide enough organic carbon to keep heterotrophic denitrifiers going or would you have to periodically dose methanol, EtOH, or sugar?

And I'll add another one:

4) Is there a size of nano that is too small for this to work?

Edited by Mr. Fosi, 06 April 2006 - 08:01 AM.

"Ocean: A body of water occupying about two-thirds of the world made for man - who has no gills." ~Ambrose Bierce

Mr. Fosi's drilled 20H w/150W Sunpod *dismantled*
Mr. Fosi's Budget 20L *dismantled*
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#7
jafoca

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It just seems to me that the RDSB size should be somewhat proportional to the tank it serves (or probably more accurate, the bio-load) I simply mean having a 29 gallon trashcan full of RDSB is probably too much for a 10gallon aquarium.

Post the question about mixing in waste on RC... I want to know what Calfo has to say.

#8
Mr. Fosi

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It just seems to me that the RDSB size should be somewhat proportional to the tank it serves (or probably more accurate, the bio-load) I simply mean having a 29 gallon trashcan full of RDSB is probably too much for a 10gallon aquarium.


You'd think so. If I were to do this, I would certainly make it somewhat proportional, but you don't want to short yourself on surface area.

I posted on that thread on RC, we'll see if they answer the question.
"Ocean: A body of water occupying about two-thirds of the world made for man - who has no gills." ~Ambrose Bierce

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#9
MrAnderson

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The origional questions stand:
1) Is biological denitrification worth trying for in a nano (6-55g) system?
2) Do you think that coils or RDSBs would have any real value in a nano system, or are they just one more gadget that we would have to muck around with?
3) Would a nano provide enough organic carbon to keep heterotrophic denitrifiers going or would you have to periodically dose methanol, EtOH, or sugar?
4) Is there a size of nano that is too small for this to work?


My opinions on this matter:

1) If it's needed...

2) "

3) The bugs will either grow to consume the load, or become dormant (or switch metabolic pathways to aerobic respiration if possible/needed) if nutrient sources becme depleted relative to population. After a certain amount of time, provided enough "environment" is provided, an equilibrium will be reached. Meaning, there will always be nitrate production, and eventually the bugs will grow to just the right level to consume as much as is being produced.

Personally I wouldn't mess with vodka and a DSB, because in that case the equilibrium is artificially forced, and deviations in dosing (everybody goes away for vacation or a weekend sometimes) can lead to fluctuations in bug population. I think it's better to let things equilibrate naturally. The bugs will grow on their own to accomodate nutrient levels.

Fluctuations in nitrate levels (eg, from feeding) could be problematic, but that applies to reefkeeping in general. Having an excess of denitrifiers isn't a good thing if the food runs out.

4) Probably not. At a certain point, the DSB may be "oversized" for a tank, but that's not harmful unless you do something to artificially mess with bug populations, like vodka. It will eventually equilibrate.

Edited by MrAnderson, 06 April 2006 - 12:19 PM.

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#10
Mr. Fosi

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I got an answer, but not from Calfo or anyone of note.

I, too, just finished an extended read of the entire thread.

I may have missed it somewhere, but did anyone give reason for why waste should not be allowed to gather on the top of the sand? Also, why would mixing such waste into the sand be a bad idea?

I thought that such waste would provide some of the much-needed carbon for the heterotrophs.


mr-fosi, If I am reading this correctly, you don't want the waste building and creating a huge bioload in the RDSB. That is an entirely different approach. You only want to "pull" nitrates out of the water column, not degrade detritus.


Bax's Answer didn't really answer my question, but I'm not sure if I want to post a follow-up for fear of being told to re-read the thread.

Anderson: What is your definition of 'needed'?

C'mon people, there have to be more than three people interested and informed enough to contribute to the discussion.

Edited by Mr. Fosi, 06 April 2006 - 04:37 PM.

"Ocean: A body of water occupying about two-thirds of the world made for man - who has no gills." ~Ambrose Bierce

Mr. Fosi's drilled 20H w/150W Sunpod *dismantled*
Mr. Fosi's Budget 20L *dismantled*
Mr. Fosi's 5 gallons of convention-defying madness *dismantled*

#11
jeremai

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Interested here, but uninformed. I really like the idea of the coil, myself - space is at a premium under my tank, and a 'drag'-style RDSB wouldn't cut it so well...

Edited by jeremai, 06 April 2006 - 05:10 PM.

pretty sure jer was referring to the length

 
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#12
MrAnderson

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Anderson: What is your definition of 'needed'?


uncontrollable nitrates
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#13
Mr. Fosi

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uncontrollable nitrates


Gotcha.
"Ocean: A body of water occupying about two-thirds of the world made for man - who has no gills." ~Ambrose Bierce

Mr. Fosi's drilled 20H w/150W Sunpod *dismantled*
Mr. Fosi's Budget 20L *dismantled*
Mr. Fosi's 5 gallons of convention-defying madness *dismantled*

#14
ProFlatlander15

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I think lgreen tried or was going to try somethig like this...a 5gal bucket filled with sand and run water over it. what is nitrate converted into? I was under the impression that was why we did WC's. I know you are trying to find how to cut down on WCs by denitrification, but what is it de-nitrified into?

#15
Mr. Fosi

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what is nitrate converted into?... but what is it de-nitrified into?


N2 gas. Inert and about 80% of the air we breathe.

You don't happen to have a link to lgreen's thread...?
"Ocean: A body of water occupying about two-thirds of the world made for man - who has no gills." ~Ambrose Bierce

Mr. Fosi's drilled 20H w/150W Sunpod *dismantled*
Mr. Fosi's Budget 20L *dismantled*
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#16
lgreen

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Success if you ask me in reefing is based on how closely we can replicate the natural ocean environment.

Berlin method (tons of live rock, agressive skimming, water changes) and BB (basically live rock and water changes) don't cut it.

Natural nitrate reduction is the way to go. Doesn't matter which you use. They all work great if you set them up correctly. Most failure stories with these advanced natural systems result from people being cheap, inpatient, or taking shortcuts.

I recommend NNR by plenum. After doing like 4 months of research on NNR, plenums just made the most sense to me.

Anyway, choose what you want, all work, but just spend a good amount of time learning how to set it up right.

If you're interested in plenums I can give you some good resources for info.

#17
Mr. Fosi

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If you're interested in plenums I can give you some good resources for info.


I'm down. Hook a brotha' up.
"Ocean: A body of water occupying about two-thirds of the world made for man - who has no gills." ~Ambrose Bierce

Mr. Fosi's drilled 20H w/150W Sunpod *dismantled*
Mr. Fosi's Budget 20L *dismantled*
Mr. Fosi's 5 gallons of convention-defying madness *dismantled*

#18
lgreen

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My tank thread: http://www.nano-reef...showtopic=79454

Oops sorry, made a mistake in my pm. Julian Sprung advocates use of remote plenums not Anthony Calfo. I have no idea what Calfo uses. I would assume DSB.

plenums:

http://www.advanceda...002/feature.htm

DSB stuff:

http://www.marinedep...y=1&SortOrder=1

Edited by lgreen, 06 April 2006 - 07:33 PM.


#19
ProFlatlander15

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So anaerobic bacteria convert nitrate into N2, nitrogen gas and some other compound. Maybe set up a part of a sump with a vodka drip, kinda like top-off. It would be semi-automatic, only needing refilling when the alcohol ran out.

Mr. Fosi I know you are trying to avoid dosing other chemicals, but if vodka was in a type of top off system, the maintainence would be that of about a frshwater top-off system. Even have a closed loop with a 5 gal bucket with a RDSB and have a vodka drip in that. No?

#20
formerly icyuodd/icyoud2

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i've also been reading up on coil denitrators
http://saltaquarium..../a/aa092702.htm theres a nice "simlpe" explanation in this link.
i plan on building one in the near future.
http://saltaquarium....enitratorplans/

Edited by formerly icyuodd/icyoud2, 07 April 2006 - 08:25 AM.


#21
MrAnderson

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So anaerobic bacteria convert nitrate into N2, nitrogen gas and some other compound.


N2 = nitrogen gas.

It's just another way of writing it.

The "other compound" is water.

:)

Maybe Set up a part of a sump with a vodka drip, kinda like top-off. It would be semi-automatic, only needing refilling when the alcohol ran out.

Mr. Fosi I know you are trying to avoid dosing other chemicals, but if vodka was in a type of top off system, the maintainence would be that of about a frshwater top-off system. Even have a closed loop with a 5 gal bucket with a RDSB and have a vodka drip in that. No?


I'm sure somebody somewhere has done this successfully, but it's highly unnatural and requires long-term consistency. Personally I wouldn't risk this.

In my opinion vodka dosing is an advanced method and should only be done by experienced aquarists who understand the general dynamics of nitrogen cycle bacteria metabolism and growth. (Just a general statement, not directed at anyone here :) ) Even then, it can be difficult to achieve equilibrium.
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#22
ProFlatlander15

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I meant N2 as nitrogen gas, but looking at my grammar now, I will admit it is not the best. Ha- yea I was too lazy to do that actual chemical equation...Thx Mr. Anderson for filling in the blank lol. So the vodka drip isn't a bad idea, you guys are just looking for something more natural, right?

The way you are going to get rid of nitrates is by somehow adding massive amounts of anaerobic bacteria. The question here is, how can that be done (right)? I suppose I should get reading....

#23
MrAnderson

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The way you are going to get rid of nitrates is by somehow adding massive amounts of anaerobic bacteria. The question here is, how can that be done (right)? I suppose I should get reading....


You only need to have enough anaerobic bacteria to remove your nitrates. Encouraging "massive" amounts artifically isn't necessary. All you need to do is provide a hospitable environment for them to thrive and they'll grow to the proper levels all by themselves. The environment can be a DSB, live rock, plenum, etc.

It's sort of like a birdhouse. Just put it there and you'll get what you want.
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#24
ProFlatlander15

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But doesn't LR have anaerobic bacteria in the middle? I take it that is not sufficient enough for nitrate reduction. could you get a large piece of LR in a 5gal bucket and run CL through it? Or are coils, RDSBs more efficient?

Edited by ProFlatlander15, 07 April 2006 - 06:48 AM.


#25
MrAnderson

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But doesn't LR have anaerobic bacteria in the middle? I take it that is not sufficient enough for nitrate reduction. could you get a large piece of LR in a 5gal bucket and run CL through it? Or are coils, RDSBs more efficient?


You're right, LR does provide an excellent source of denitrification. In many tanks this is sufficient for complete denitrification. But in others it is not. Perhaps this has to do with the bioload, the health of the rock (dead material within it), etc.
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