What is the nitrite concentration of your mature reef? And why it may matter.

[Hans-Werner]

If it this way - it may be more important with a good nitrification filter in saltwater compared with freshwater.

The drawback of a nitrification filter is that it competes with corals for ammonium. I think there is a good reason why trickle filters and also other aerobic filters in reef aquaria are out of style. In my eyes we rather should avoid everything that speeds up ammonium oxidation, at least as long as no ammonium can be measured in the water.

I got aware of the "reverse process" of nitrite generation from nitrate when a shop called me complaining about a high nitrate indication of a test kit in a system that has a sulfur denitrification filter. I recommended to check for nitrite because the denitrification could be incomplete and release nitrite and that was the answer to the problem.

Since then I was confronted with this problem several times and nitrite seems to be present in more tanks than previously thought, also in mature systems, especially if they do organic carbon dosing, which may also support nitrate respiration.

My solution would be, not to have more nitrification but to have less nitrate. In my eyes with less (no) nitrate everything is perfect. The corals get the ammonium they need, algae may get nitrogen starved and nitrite does not build up since there is no excess of dissolved nitrogen compounds that may form nitrite.

The only problem that may remain is cyanobacteria which are mainly an optical problem and rarely harm corals in my experience, at least under these conditions. Cyanobacteria could get iron starved without affecting the corals seriously but I think this is a bit tricky and not so easy to achieve. However, it contradicts the recommendation of some ICP-OES laboratories that recommend iron concentrations above their detection limits of ICP-OES.

 

[Lasse]

especially if they do organic carbon dosing, which may also support nitrate respiration.

Yes it support nitrate respiration and make it more complete -My experiences from denitrification filters says that nitrite build up happens when DOC addition or production is to low. DOC serve as electron donor in the denitrification driven by heterotrophic bacteria. On the other hand - DOC in the water also promote the growth of aerobic fast growing heterotrophic bacteria that will concur out autotrophic nitrification bacteria both from space and oxygen. Egg or hen - that´s the question

In my eyes with less (no) nitrate everything is perfect. The corals get the ammonium they need, algae may get nitrogen starved and nitrite does not build up since there is no excess of dissolved nitrogen compounds that may form nitrite.

According to microalgae - among fresh water aquarists - many of these common algae have no ability to convert nitrate into ammonium but their growth will be high in presence of NH4, therefore is fertilization with NH4 a large No-No for planted aquariums. They have the opposite standpoint here - its the dam egg or hen discussion again or maybe the sandwich cat

Sincerely Lasse

 

[Hans-Werner]

According to microalgae - among fresh water aquarists - many of these common algae have no ability to convert nitrate into ammonium but their growth will be high in presence of NH4, therefore is fertilization with NH4 a large No-No for planted aquariums. They have the opposite standpoint here - its the dam egg or hen discussion again or maybe the sandwich cat

In my experience with freshwater aquaria the image I see is a little different. I had South America aquaria with tetras, loricariids, and, as one main interest, Echinodorus spp..

Most aquarium plants prefer nitrate as their nitrogen source because they originate from land plants. In fact Echinodorus and many other aquarium plants are marsh plants, living emerged, exposed to air, most of the time but can also adapt to submerged growth.

Corals prefer ammonium as their nitrogen source.

In each environment algae may be outcompeted if competitors get their preferred nitrogen compound and may outcompete their competitors if these don't get their preferred nitrogen compound.

Addition: To my knowledge most (all?) algae can induce nitrate reductase and reduce nitrate for assimilation. The well-known and widespread f2 algae medium and BG11 medium (except traces) don't even contain ammonium.

 

[KGV]

In my experience with freshwater aquaria the image I see is a little different. I had South America aquaria with tetras, loricariids, and, as one main interest, Echinodorus spp..

Most aquarium plants prefer nitrate as their nitrogen source because they originate from land plants. In fact Echinodorus and many other aquarium plants are marsh plants, living emerged, exposed to air, most of the time but can also adapt to submerged growth.

Corals prefer ammonium as their nitrogen source.

In each environment algae may be outcompeted if competitors get their preferred nitrogen compound and may outcompete their competitors if these don't get their preferred nitrogen compound.

@Lasse @Hans-Werner @taricha That was a new and very interesting addition to my basic understanding of denitrification in saltwater tanks. Thanks!

 

[Lasse]

Most aquarium plants prefer nitrate as their nitrogen source because they originate from land plants

I would not say prefer - I would say manage. It cost energy if they use NO3 - NH4 can diffuse into the plant (or rot system) NO3 can´t be distributed in the organism it has to be converted into NH4 and that cost energy. IMO - they prefer NH4 as the fast nitrogen source and can use NO3 as a long time source. There is a reason why NH4NO3 (ammonium nitrate) is the most common nitrogen artificial fertilizer.

Corals prefer ammonium as their nitroge source.

Yes but they can use NO3 - free NH4 is always short-lived in a real reef - an small amount of NO3 will always be there. I would not be surprised if most of the nitrogen used by zooxanthella's is local produced NH4 (locally = inside the coral animals tissue) and the ability to use NO3 has been developed during periods of starvation. IMO - there is not a chance that not even one NH4 molecule can reach the top of a natural reef without being consumed before.

Sincerely Lasse

 

[Hans-Werner]

I would not say prefer - I would say manage. It cost energy if they use NO3 - NH4 can diffuse into the plant (or rot system) NO3 can´t be distributed in the organism it has to be converted into NH4 and that cost energy. IMO - they prefer NH4 as the fast nitrogen source and can use NO3 as a long time source. There is a reason why NH4NO3 (ammonium nitrate) is the most common nitrogen artificial fertilizer.

I am quite sure "prefer", very sure.
- I have read a book on mineral nutrition of wild plants and most plants really prefer nitrate with moorland plants growing on acidic peat and humus soils being the exceptions preferring ammonium.
- My hobby is plants and plants have been my approach to understanding corals. I came from freshwater aquaria originally. Also indoor plants like nitrate. It is because of the nutrient/mineral balance. Most other ions plants need in large quantities are cations, K, Ca, Mg, nitrate is the ideal anion balancing the cation uptake.
However, I have to confess most indoor plants like some ammonium besides nitrate. I think it is to keep phosphate mobile and prevent it from being deposited in vessels and intercellular space. It is an effect of internal pH which is different with nitrate and ammonium nutrition.

Nevertheless, the reason why ammonium or ammonium nitrate are preferred agricultural fertilizers is a different one: While nitrate is washed out of the soil and goes directly into the groundwater, ammonium adsorbs to clay minerals. When released it is nitrified ensuring a slow and quite continuous flow of available nitrogen compounds.

Yes but they can use NO3 - free NH4 is always short-lived in a real reef - an small amount of NO3 will always be there. I would not be surprised if most of the nitrogen used by zooxanthella's is local produced NH4 (locally = inside the coral animals tissue) and the ability to use NO3 has been developed during periods of starvation. IMO - there is not a chance that not even one NH4 molecule can reach the top of a natural reef without being consumed before.

Of course science also answers this question: Normally in reefs there is a predominance of ammonium or maybe half ammonium and half nitrate. Generally nitrate is also designated "new nitrogen" while ammonium is designated "recycled nitrogen". This already explains why there is a predominance of ammonium in unpolluted reefs: Nitrogen compounds are recycled so fast in most reefs, there is simply more excretion of ammonium, i. e. by fish, sponges and all the other heterotrophic organisms than nitrification taking place. And, ammonium is taken up again by corals and algae, so nitrification is a process of minor importance. Nitrate usually is the nutrient flushed into the reef from outside, from land, rivers and upwellings --> new nitrogen, from outside.

There is even a proven positive effect to corals of the ammonium excreted by fish resting and living in corals.

There are several scientific publications from recent years ascribing positive effects on corals to ammonium and negative effects on corals to nitrate.

 

[vlangel]

Wow, this is such an interesting discussion. I just wished that I understood the science and chemistry side more so that I could have a better idea of exactly what is being said! LOL.

My 56 gallon softie/LPS display tank is 6 years old, with live rock that is 20+ years old. It has DSBs in both the display and 30 gallon fuge. It also has differing macro algae in both. I operate with heavy input, (food, trace minerals) and heavy output (5% weekly water changes) and my nutrients are high, ( nitrate 30 ppm and phosphates .15 ppm). My tank system has no nuisance algae issue except rust color on the sand when nutrients get too low. Practically speaking I know how to manage my tank system but academically I wished I understood better what is taking place.

 

[WVNed]

I read these posts with great interest. I get some of it. I still feel like I am practicing witchcraft though.
I dump large amounts of food in including big chunks for large fish and eels.
I strictly control phos with LaCl on a doser. 50ml a day straight into the sump. I have heard everything will die but it hasn't so far.
I haven't done a nitrite test in a decade. Never knew I needed to. After thinking on this can I assume that if my nitrate reactors bring my testable nitrates down to 2-5 like I expect them to I do not have substantial levels of nitrites.
I use a Hanna High range now which says it is affected by nitrites. My Nitrates were 38 on Sunday. Perhaps that number is a false high caused by nitrites coming out of the sulfur reactors as they colonize.
Even if I assume that number is derived by a combination of nitrate and nitrite in my system I don't see it as high enough to be a problem.

Am I wrong?

 

[ReefJonas]

I known it may not affect the animals in your aquarium, but measurable nitrite will affect the amount of NO3 that you measure (depending on the test that you use).

I have a 1.5 year-old reef and I measure 0.150 ppm nitrite (Hanna ULR). I was surprised it was this high. This means that for some NO3 tests, for example Tropic Marin, 0.150 ppm nitrite will account for 15 ppm of measured NO3. And if you measure 15 ppm NO3 with the Tropic Marin test, there may actually be no NO3 in your system at all. If you grow Acropora, perhaps you decide to take drastic measures to get the NO3 value down by reducing your feeding and create a major problem.

Very few measure nitrite once the tank is matured. Perhaps we should? Is my 0.150 ppm nitrite high, indicating a problem with the nitrification cycle? Could high nitrite be typical for tanks with heavy feeding? I grow acros and use heavy in/out, with no supplements but kalk and 2-part.

@Lasse @Hans-Werner @taricha. Am I correct? Any thoughts?

That’s fully correct. The factor 100 for FM is probably because they have shorter waiting time before take the no3 reading. So quite small amount of nitrate has time to reduce to nitrite and thus the already existing nitrite has a large impact in %. The benefit is a larger range (up to 20 ppm) but as said more influence from nitrite.
Red Sea wait 9 min so there probably almost all nitrate is reduced to nitrite before take the reading and thus a much lesser factor of influence from already existing nitrite. But on the negative side is a smaller range (only up to 4 ppm for Red ses test ), as more colour will develop/nitrate conc.

The true no2 conc in a tank is in mature tank more than many believe as not so many measure nitrite. It’s often around 0.02-0.03. This is not a problem at all but reflects a mature tank AMI.

For other tests like salifert nitrate I think factor is something between FM and Red Sea, like 25. So in practice not so sensitive to nitrite as FM test are.
/Jonas

 

[Lasse]

I am quite sure "prefer", very sure.
- I have read a book on mineral nutrition of wild plants and most plants really prefer nitrate with moorland plants growing on acidic peat and humus soils being the exceptions preferring ammonium.
- My hobby is plants and plants have been my approach to understanding corals. I came from freshwater aquaria originally. Also indoor plants like nitrate. It is because of the nutrient/mineral balance. Most other ions plants need in large quantities are cations, K, Ca, Mg, nitrate is the ideal anion balancing the cation uptake.
However, I have to confess most indoor plants like some ammonium besides nitrate. I think it is to keep phosphate mobile and prevent it from being deposited in vessels and intercellular space. It is an effect of internal pH which is different with nitrate and ammonium nutrition.

Nevertheless, the reason why ammonium or ammonium nitrate are preferred agricultural fertilizers is a different one: While nitrate is washed out of the soil and goes directly into the groundwater, ammonium adsorbs to clay minerals. When released it is nitrified ensuring a slow and quite continuous flow of available nitrogen compounds.

Let us sort up this first. The word "prefer" is a little bit confusing because it is perspective depended. I´ll think we have different perspectives here. Your is from the whole system and my from the energy balance of the plant in question. Start with the whole system (I´m concentrate on terrestrial plant system here) If the rots take up NH4 (the most common ammonia species at pH lower than 7) - the uptake process will produce 1 proton down to the soil - if the uptake is NO3 - the process can produce 1 HCO3/OH ion if it is processed directly, none if stored.

Drawing from here

​

This is for neutral a acid soils. Alkaline soils has its own difficulties because some NH3 will be formed from used NH4 creating damage on the rots. However most plants try to create a pH around 6.5 around the rots and NH4 in the fertilizer will create that .

There is also a risk for cation antagonism between NH4 and the other important cations (Ca, K and Mg) if the NH4 part is to high

From a system point of view - a combination is preferred in most cases and soils.

However - from the energy laws of the plants perspective - it is IMO a different case. Below is a Google translation from a Swedish text describe my standpoint rather good. My Bold

Plant amino acid synthesis

If ammonia and ammonium are both available to the plant at the same time, the plant usually absorbs more ammonia than nitrate from the soil. The cumulative uptake of ammonia customers measurement for three weeks is for soybeans approximately twice as large as the uptake of nitrates during the same period at equal concentrations of both substances. However, the plant can absorb most nitrogen in general if it is available in the form of both nitrate and ammonia (Jean-Fransois, Morot Gaudry. 2001. chap. 4). Since 99% of the ammonia present in the soil at physiological pH around seven is in a protonated state as ammonium ion NH4 +, it is assumed that the plant takes up this form and not unprotonated NH3. Uptake of ammonia contaminates the soil where the plant grows while uptake of nitrate and nitrite ions makes the soil more basic. The uptake of ammonia from the soil deteriorates the more acidic the soil becomes. Nitrate and nitrite can to some extent are transported in the plant and stored in vacuoles and other parts of the plant body. Plants cannot use nitrate and nitrite ions directly for amino acid synthesis but must first convert these to ammonia using enzymes before pre-amino acid synthesis can be used. Since ammonia is the form of nitrogen that can be used directly by the plant to form amino acids, ammonia must be free in the plant for a short time, but it can not be in any major concentration in the sap without the plant being damaged (Jean-Fransois, Carrot Gaudry. 2001. chap. 4). Therefore, ammonia is rapidly incorporated into the amino acids when it is taken up by the plant, or created from nitrite. Ammonia formed by cyanobacteria in the roots of the plant can be used in the same way, just as ammonia formed by the plant itself from nitrite

Normally in reefs there is a predominance of ammonium or maybe half ammonium and half nitrate. Generally nitrate is also designated "new nitrogen" while ammonium is designated "recycled nitrogen". This already explains why there is a predominance of ammonium in unpolluted reefs: Nitrogen compounds are recycled so fast in most reefs, there is simply more excretion of ammonium, i. e. by fish, sponges and all the other heterotrophic organisms than nitrification taking place. And, ammonium is taken up again by corals and algae, so nitrification is a process of minor importance. Nitrate usually is the nutrient flushed into the reef from outside, from land, rivers and upwellings --> new nitrogen, from outside.

There is even a proven positive effect to corals of the ammonium excreted by fish resting and living in corals.

I have not seen any figures of measured ammonia in the water column of a reef compared with measured NO3 levels in the same water but what i have understand - the reefs internal consumption of NH4 is so high that no leftovers (free NH4 in the water) can be measured. If you have figures of this (NH4/NH3 concentration in the water above a reef) I would be glad to see them and change my mind.

There is even a proven positive effect to corals of the ammonium excreted by fish resting and living in corals.

I will use another word in this discussion and that is proximity to the source - the consumer nearest the production source will benefit of it. It is important in your example but - IMO - also in another case. The organism responsible for the photosynthesis (read primary production) lives in the body of a heterotrophic organism that transport already synthesized amino acids from its eating of different plankton or bacteria. I would be very surprised if not most of the nitrogen that zooxanthella need not comes along this internal pathway.

Do the corals or the whole system need NO3 free in the water - I´m not sure about the corals (just like you) but rather sure for the whole system. However - our experiences the last decades is that it is not good to zero out neither PO4 and/or NO3 from a holistic point of view

I´m with you that the huge, huge internal turn over of Nitrogen in a reef is predominated by NH4/NH3 but it is always the "new" nitrogen that make the reef to grow in biomass - IMO.

Sincerely Lasse

 

[Hans-Werner]

The organism responsible for the photosynthesis (read primary production) lives in the body of a heterotrophic organism that transport already synthesized amino acids from its eating of different plankton or bacteria. I would be very surprised if not most of the nitrogen that zooxanthella need not comes along this internal pathway.

You think the coral polyp provides the zooxanthellae with amino acids? The predominant theories say it vice versa: The coral polyp provides the zooxanthellae with ammonium, the zooxanthellae form amino acids from ammonium and fixed carbon and return amino acids to the coral polyp.

I have not seen any figures of measured ammonia in the water column of a reef compared with measured NO3 levels in the same water but what i have understand - the reefs internal consumption of NH4 is so high that no leftovers (free NH4 in the water) can be measured. If you have figures of this (NH4/NH3 concentration in the water above a reef) I would be glad to see them and change my mind.

You can find numbers for example here, here (if you have access?) and of course in the Sorokin book "Coral Reef Ecology". Shantz does a comparison ammonium - nitrate in his dissertation but I am not sure if you can find natural concentrations but likely. I am sure there are much more publications with numbers, for example if you search the publications cited by Shantz. This is only what I have found in a very quick search.

 

[Lasse]

The coral polyp provides the zooxanthellae with ammonium

That´s what I have thought before but as I understand today - organisms can´t transport free NH4 without risk for cell-damage (especially in environment with pH above 8) and the nitrogen transport form inside an organism is mainly amino acids. It looks like a paradox for me. For me it is not likely that the zooxanthella's produce amino acids for the host - for me its more likely that the host take advantage of the glucose production from the photosynthesis through controlling the growth of the zooxanthella. But that´s only my idea

The links about NH4 concentrations you provide give me one figure of NH4 concentration but that was on a reef affected by run off water.

Sincerely Lasse

 

[Treefer32]

My recommendation is to widely ignore nitrate and nitrite all together and concentrate on phosphate (hey, wait a moment, of course we want to sell our nitrate tests. ). Ok, test for nitrite and nitrate, but just as information and not to take any serious measures before you are absolutely sure. Why take any measures at all if nothing else is wrong? Like I have learnt in this forum, if it ain't broke, don't fix it

 

[Treefer32]

My recommendation is to widely ignore nitrate and nitrite all together and concentrate on phosphate (hey, wait a moment, of course we want to sell our nitrate tests. ). Ok, test for nitrite and nitrate, but just as information and not to take any serious measures before you are absolutely sure. Why take any measures at all if nothing else is wrong? Like I have learnt in this forum, if it ain't broke, don't fix i

I disagree because there is a line where corals start dyeing and fish health starts decreasing. I've seen it my 4 year old reef. Nitrates testing over 40 and corals start closing up. At 50+ they start having tissue death. Same with phosphates. As phosphates climb over .2 ppm my corals stop growing, start having tissue recession and or flat out death.

I've got countless coral skeletons to prove that nutrients cause death. It sucks, it's expensive and is disheartening to see expensive corals die.

 

[damsels are not mean]

I disagree because there is a line where corals start dyeing and fish health starts decreasing. I've seen it my 4 year old reef. Nitrates testing over 40 and corals start closing up. At 50+ they start having tissue death. Same with phosphates. As phosphates climb over .2 ppm my corals stop growing, start having tissue recession and or flat out death.

I've got countless coral skeletons to prove that nutrients cause death. It sucks, it's expensive and is disheartening to see expensive corals die.

I did not experience this when I rebooted my 10 year old reef. The tank tested at over 200 nitrate from no maintenance for several years. I added some new frags including sps and those were growing their base visibly by the end of the week. A new shrimp and some new fish were added, no sign of stress.

Now what if this was actually nitrite building up and causing interference? I have not tested nitrite in a long time but I wish I had known about this when I did that. Would have been a good case study.

 

[JCOLE]

Decided to try my Hanna Nitrite checker for the first time last night. I got a reading of 50 ppb. Conversion to No2 is 3.29 so my Nitrite apparently is 164.5. I also tested my Nitrate with my Hanna as well and got a reading of 31 ppm.

 

[Lasse]

Decided to try my Hanna Nitrite checker for the first time last night. I got a reading of 50 ppb. Conversion to No2 is 3.29 so my Nitrite apparently is 164.5. I also tested my Nitrate with my Hanna as well and got a reading of 31 ppm.

164.5 is ppb nitrite - it is equal to 0.1645 ppm nitrite

Sincerely Lasse

 

[JCOLE]

164.5 is ppb nitrite - it is equal to 0.1645 ppm nitrite

Sincerely Lasse

Thank you Lasse. I seen where you say to divide by 1000. In Hanna's instructions it says to multiply by 3.29 only. Is there a reason they don't mention that?

Edit - I think I got it. The conversion of 3.29 is for PPB of No2, correct? For PPM then thats where I would divide by 1000?

 

[Lasse]

Edit - I think I got it. The conversion of 3.29 is for PPB of No2, correct? For PPM then thats where I would divide by 1000?

You got it

The formula for nitrite is NO2 - it means 1 atom N to 2 atoms O. Atomic mass for N is 14 and for O - 16. The whole molecule NO2 have a mass of 14 + 2*16 = 46. There is 2 common ways of calculation of concentrations when N is involved - One report the concentration of the whole molecule - the other only of the atoms. In this case - it is often expressed as NO2 (concentration of the whole molecule) or as NO2-N (concentration of the N atom) that is reported. The actual concentrations can as example be expressed as mg/L (ppm) or µg/l (ppb) there 1 mg/L (ppm) is 1000 µg/L (ppb). The Hanna ULR marine nitrite checker report in µg/L (ppb) NO2-N. To get your measurement in mg/L (ppm) NO2 you need to first multiply the result with 46/14 = 3.29 - it give you the concentration in µg/L (ppb) NO2. But you want it as mg/L (ppm) - easy - just divide with 1000

Sincerely Lasse

 

[JCOLE]

You got it

The formula for nitrite is NO2 - it means 1 atom N to 2 atoms O. Atomic mass for N is 14 and for O - 16. The whole molecule NO2 have a mass of 14 + 2*16 = 46. There is 2 common ways of calculation of concentrations when N is involved - One report the concentration of the whole molecule - the other only of the atoms. In this case - it is often expressed as NO2 (concentration of the whole molecule) or as NO2-N (concentration of the N atom) that is reported. The actual concentrations can as example be expressed as mg/L (ppm) or µg/l (ppb) there 1 mg/L (ppm) is 1000 µg/L (ppb). The Hanna ULR marine nitrite checker report in µg/L (ppb) NO2-N. To get your measurement in mg/L (ppm) NO2 you need to first multiply the result with 46/14 = 3.29 - it give you the concentration in µg/L (ppb) NO2. But you want it as mg/L (ppm) - easy - just divide with 1000

Sincerely Lasse

Perfect explanation! Thanks @Lasse

Hanna should copy what you wrote and put all of that in their manual.