Nitrate reducing tanks!

[Euphyllia97]

Hi guys!

Hitting the 8 months mark with my new tank and I have Quite a good amount of rocks. I was wondering if some of you have a tank, which uses up nitrates faster than they are produced. (No water changes or carbon dosing)

I know it takes a long time to establish a decent colony size of bacteria that turn nitrate into nitrogen gas.

If you do, could you maybe answer the following: Tank age, nitrate consumption over a certain time, tank size, livestock.

 

[lapin]

You can force this with carbon dosing.
I know there are threads here where users have 0 nitrate or 0 phosphate and need to raise it. You might message one of those people if you dont get any responce here

 

[Indytraveler83]

A lot of us with heavy coral tanks struggle with nitrate bottoming out. My system is about a year old, has about 25 frags and 4 large colonies (mostly lps) and it's always a struggle to keep any nutrients in the tank.

I have quite a few fish (and getting more) but I don't keep any large or heavy bioload fish, which contributes to my struggle.

Randy Holmes-Farley has instructions for dosing nitrate in one of his threads on here. It's helped my reef a ton, and if done right can be used to help keep levels stable.

 

[Euphyllia97]

You can force this with carbon dosing.
I know there are threads here where users have 0 nitrate or 0 phosphate and need to raise it. You might message one of those people if you dont get any responce here

Thing is I’m interested in seeing if some tanks are able to do this without adding any source of carbon myself.
I know there are a lot of ways to get 0 values although I’m more interested in the non-manipulated way.

Keeping mine at 10 ppm so I’m not looking to reduce my own values. Just wondering of there will be a time that I will have to dose No3 and Po4

 

[Indytraveler83]

Thing is I’m interested in seeing if some tanks are able to do this without adding any source of carbon myself.
I know there are a lot of ways to get 0 values although I’m more interested in the non-manipulated way.

Keeping mine at 10 ppm so I’m not looking to reduce my own values. Just wondering of there will be a time that I will have to dose No3 and Po4

Absolutely. I run no carbon at all. I have a 90 G system with about 100 lbs of live rock and a large refugium. I run a skimmer about half the time, and leave dirty filter socks in to try and help build up the nitrates a little!! It is an upgrade off a 54G system that had the same problem. I used "old" live rock from some very established system (about 25 lbs came from a 20+ year old display), so I think that has a lot to do with it.

I'm no chemist, but I think large amounts of nitrate consumers such as LR, macroalgae and corals (especially when corrailine algae takes hold) can overwhelm systems that don't have a heavy bioload. My largest bioload fish are a pair of black mollies. Aside from that I keep small wrasses, anthias, two small clowns, similar small fish (most of the fish I keep are ok to have in 20-30 gallon systems).

I also have absolutely no luck with tangs, which I know can play a massive role in nutrients in a system, and suspect this may have a lot to do with it.

 

[Heart of Dixie]

I have a 150 gal mixed reef tank that has been set up for several years. The system includes 55 pounds of pukani live rock, a Life Reef skimmer and a 20 gallon refugium full of chaeto that is regularly harvested. I have to dose n03 every week to keep it from falling to zero and dose p04 when it bottoms out to 0, the sign to pull some of the macro algae out. P04 is usually anywhere between .015 and .08. I feed LRS every 3 days and sinking pellets in between. I do not dose carbon, run GFO or activated carbon. Stock: 9 fish, some sps, lps and a few softies

 

[LRT]

Following. I have 4 tables running on 160-180 gallon res with 300lbs of live rock.
1 clown fish, a dozen hermit crabs and snails, all kind of oysters clams attached to live rock.
2 tables full if mushrooms all sorts.
O nitrates is all I can seem to achieve naturally

 

[NS Mike D]

My first year I was bottoming out nitrates and phosphates. Then I changed test kits and the problem went away.

API isn't sensitive enough for low level reef tanks

 

[Dan_P]

Hi guys!

Hitting the 8 months mark with my new tank and I have Quite a good amount of rocks. I was wondering if some of you have a tank, which uses up nitrates faster than they are produced. (No water changes or carbon dosing)

I know it takes a long time to establish a decent colony size of bacteria that turn nitrate into nitrogen gas.

If you do, could you maybe answer the following: Tank age, nitrate consumption over a certain time, tank size, livestock.

Nitrates are either being exported or are not being formed.

Nitrate comes from the oxidation of nitrite which comes from the oxidation of ammonia. If ammonia is consumed before it is oxidized, you would no nitrate in your water. I wonder how you could differentiate denitrification from ammonia consumption?

 

[Euphyllia97]

Nitrates are either being exported or are not being formed.

Nitrate comes from the oxidation of nitrite which comes from the oxidation of ammonia. If ammonia is consumed before it is oxidized, you would no nitrate in your water. I wonder how you could differentiate denitrification from ammonia consumption?

Good question. But I think almost ll of the ammonia gets consumed by bacteria right away, no? I know some things in the tank can consume ammonia directly but I think this is quite limited.

 

[Dan_P]

Good question. But I think almost ll of the ammonia gets consumed by bacteria right away, no? I know some things in the tank can consume ammonia directly but I think this is quite limited.

As a first approximatio, ammonia is the preferred inorganic nitrogen source. Anything in the aquarium that sucks up nitrate will take ammonia first. Ammonia may also inhibit nitrate uptake until the ammonia level is depleted.

 

[Euphyllia97]

As a first approximatio, ammonia is the preferred inorganic nitrogen source. Anything in the aquarium that sucks up nitrate will take ammonia first. Ammonia may also inhibit nitrate uptake until the ammonia level is depleted.

Oh thank you for the information! I had no idea it went like that. So am I right to assume the more corals you have, the less likely it will be to have a high ammonia reading (and an increase in nitrate) when something in your tank dies? Or is the uptake of ammonia by corals neglegible?

 

[taricha]

I wonder how you could differentiate denitrification from ammonia consumption?

You might've hinted at this before. Could we expect an Oxygen consumption difference between an ammonia oxidized to nitrate and one incorporated into biomass? Or an Alk difference?
From a big picture perspective, ammonia to NO3 consumes 3O per N, and it looks like bacterial biomass might be 1.5 to 2 Os per N...

from Content of carbon, nitrogen, oxygen, sulfur and phosphorus in native aquatic and cultured bacteria[pdf]
but maybe the details are too messy for that kind of reasoning.

 

[Dan_P]

Oh thank you for the information! I had no idea it went like that. So am I right to assume the more corals you have, the less likely it will be to have a high ammonia reading (and an increase in nitrate) when something in your tank dies? Or is the uptake of ammonia by corals neglegible?

I have heard of people dosing ammonium chloride. I would guess coral take up ammonia as well.

The threat of an ammonia spike when something dies relates to its mass. Very roughly speaking, small dead mass, small ammonia spike, large mass large spike. I would not worry about as much as maintain vigilance on the amount of dead stuff lying around. I am interested in but have not pursued the subject of determining how much of an ammonia spike an aquarium can handle.

 

[Dan_P]

You might've hinted at this before. Could we expect an Oxygen consumption difference between an ammonia oxidized to nitrate and one incorporated into biomass? Or an Alk difference?
From a big picture perspective, ammonia to NO3 consumes 3O per N, and it looks like bacterial biomass might be 1.5 to 2 Os per N...

from Content of carbon, nitrogen, oxygen, sulfur and phosphorus in native aquatic and cultured bacteria[pdf]
but maybe the details are too messy for that kind of reasoning.

Nice paper @taricha.

If all the aquarium microbial metabolism occurred in the water, might we take a sample of it, dose NH3 and measure the nitrate formed, and assume any missing ammonia is the result of assimilation? Doing one experiment in light and one in dark might help gauge what type of organism is assimilating the ammonia. And could we estimate the capacity of the water to eliminate ammonia by dosing ammonia until it started to accumulate?

I talk about this as if it were a simple chemistry analysis, but executing this would be quite a bit more complicated. Lots of controls needed. @brandon429 reminds us that there is plenty of surface area in an aquarium to rid it of ammonia. I have been toying with the idea to see how much of this capacity is in the water. I wonder if sampling the substrate and dosing it with ammonia is a fool’s errand?

I shared these ideas to address your question. Maybe we have to look at the fate of ammonia rather than oxygen to describe how the aquarium handles ammonia, whether it is heavier on oxidation or assimilation. I have this notion that carbon dosing pushes the aquarium towards assimilation, starving the oxidizers and subsequently the denitrifyers. I think this is why @Belgian Anthias feels carbon dosing might be harming a reef system.

I have an index card and scrap paper collection of ideas. This one is already on it.

 

[Nano sapiens]

Nitrates are either being exported or are not being formed.

Nitrate comes from the oxidation of nitrite which comes from the oxidation of ammonia. If ammonia is consumed before it is oxidized, you would no nitrate in your water. I wonder how you could differentiate denitrification from ammonia consumption?

A microbial report from AquaBiomics is one way to get an idea, at least. For example, my small system's report shows a good helping of nitrifying bacteria/archaea which must be utilizing at least a good portion of the ammonia produced. I posit that in a healthy balanced reef system, denitrifiers would also be present in good numbers when the system has a large number of nitrifiers and nitrate concentration is low. It follows that if a system tests low in regards to nitrifying microorganisms, then one would expect that either ammonia production is quite low and/or ammonia is largely being utilized by macro organisms (according to papers I've read, corals do have a preference for ammonia as it's less metabolically intensive to utilize than nitrate).

 

[taricha]

I was thinking of aquabiomics here too.
There's an article on BattleCorals growing system.
There's a huge amount of ammonia oxidizers / nitrifiers.
Eli discusses the factors here

EM: One of the things that really stood out about your tank for me is the high levels of nutrient-processing microbes. Ammonia-oxidizing microbes made up almost 8% of your sample, which is higher than about 85% of aquariums I’ve tested, about twice as high as the average sample. Your sample also had high levels of nitrite-oxidizing bacteria (0.9%), which is among the highest of any tanks tested (higher than 96% of samples), and over 3-times higher than the average sample.

This may not come as a surprise, since we expect to find these in a tank with a functional biofilter. But in fact, many established tanks have very low levels of these microbes. In some cases, nitrite-oxidizing bacteria aren’t even detected (although they’re likely still present at low levels).

As I review these surveys from different tanks, lately I’ve been thinking about competition between microbes and other organisms for ammonia. I’m considering the hypothesis that some tanks process most of the ammonia through nitrification, some through assimilation by invertebrates or heterotrophic bacteria, and some through assimilation by algae. In this framework, your tank appears to process most of its ammonia through nitrification, the classic pathway we all learn about when cycling a new tank.

To evaluate this interpretation of your system as “nitrification-dominated” I’d like to ask, do you deliberately grow any macroalgae in this system (e.g. in a reactor?) Similarly, would you say your tank has a large biomass of sponges or very little?

Figure 4: A view showing some of the live rock housed in the system tested for this article. Photo credit: Adam Derickson.

AD: I dont run algae or any means to keep macro in my systems any more but I do have a lot of different sponges in “cryptic” zones.



EM: So it sounds like no major algal populations to compete for ammonia, but perhaps some competition by sponges. Since I believe you don’t carbon dose, heterotrophic bacterial uptake is also likely pretty low in this system. This seems consistent with a system processing most of its ammonia through nitrification rather than heterotrophic or photoautotrophic assimilation.

Another factor that’s likely to influence these communities is the total amount of ammonia processed through the system. In principle an aquarium can maintain stable levels by matching high nutrient export to high nutrient import, or by matching low export to low import. But the former would be expected to support higher populations of ammonia-oxidizing microbes.

@AquaBiomics the one thing I didn't see you address in the interview, the system is bare bottom? Wondering if that might also contribute to finding more nitrifiers in the sample?

 

[Dan_P]

A microbial report from AquaBiomics is one way to get an idea, at least. For example, my small system's report shows a good helping of nitrifying bacteria/archaea which must be utilizing at least a good portion of the ammonia produced. I posit that in a healthy balanced reef system, denitrifiers would also be present in good numbers when the system has a large number of nitrifiers and nitrate concentration is low. It follows that if a system tests low in regards to nitrifying microorganisms, then one would expect that either ammonia production is quite low and/or ammonia is largely being utilized by macro organisms (according to papers I've read, corals do have a preference for ammonia as it's less metabolically intensive to utilize than nitrate).

Have you heard about anyone having good success dosing ammonium chloride to feed coral?

 

[Nano sapiens]

Have you heard about anyone having good success dosing ammonium chloride to feed coral?

I do vaguely remember reading something about this. Then again I don't dose anything other than Kalkwasser these days, so I don't pay that much attention to all the substances people are adding to their systems.

 

[Belgian Anthias]

Nice paper @taricha.


I shared these ideas to address your question. Maybe we have to look at the fate of ammonia rather than oxygen to describe how the aquarium handles ammonia, whether it is heavier on oxidation or assimilation. I have this notion that carbon dosing pushes the aquarium towards assimilation, starving the oxidizers and subsequently the denitrifyers. I think this is why @Belgian Anthias feels carbon dosing might be harming a reef system.

I have an index card and scrap paper collection of ideas. This one is already on it.

The way ammonia is handled? It is all about growth rates, organic carbon availability and energy needed.
If free organic carbon is available by dosing, some bacteria must not break down organics to retrieve it ( remineralization) and r-strategists will use the inorganic nutrients and building materials available in the water column for very fast growth, nutrients normally used by slower-growing organisms, autotrophs including symbiodinium. As they must not spend much energy on retrieving their carbon source they may grow very fast, using up most ammonia very fast. Normally the carrying capacity of a closed system is based on autotrophic ammonia reduction capacity. By adding free carbon the carrying capacity shifts towards heterotrophic growth. If this is maintained for a period of time ( dosing based on the nitrate level) the autotrophic carrying capacity may be lost. As those r-strategists need 40x more building materials to maintain the same carrying capacity as would autotrophs, the availability of phosphorus and all other building materials are essential for maintaining the bio-load of the system as sufficient autotrophic ammonium reduction capacity is not available. Knowing growth rates in the coral holobiont and thereby their own food supply is managed by the coral by providing organic carbon and organic phosphorus ( managing heterotrophic growth and nutrient availability). It has been shown free organic carbon availability will mess up the holobiont and high DOC availability harms and even may kill corals. I do not think carbon dosing may harm corals if dosed based on the nitrate level, I am convinced dosing carbohydrates this way will influence coral growth and even may kill them

Adding free ammonia NH3 will also have a huge effect on the existing nutrient balance and growth rates, organisms using ammonia as a nitrogen source may grow +- 8x faster as when using nitrate as a nitrogen source.
As ammonia mainly is produced due to remineralization and the energy production needed, no building materials are produced for using up that ammonia for metabolism, and knowing heterotrophic ammonium reduction needs +- 40x building materials as autotrophic ammonium reduction ( nitrification). Nitrate is the end product of the aerobic remineralization process. The produced nitrate is essential for supporting growth when ammonia is not available, for anaerobic remineralization, sulfate reduction, and HS removal ( denitrification), closing the nitrogen cycle. If free NH3 is added, depending on organic carbon and other building materials availability nitrate or protein will be produced using up ammonia. Photo-autotrophs may grow 5x faster when using ammonia and they do not need an organic carbon source and have an unlimited energy source.