Do we need Nitrate in a reef tank?

[Dan_P]

Discussing this question from a different approach, one question is whether there is any organism in a reef tank with an absolute requirement for nitrate, which cannot be satisfied by another molecule.

I'm not aware of any such organism larger than microbes, and I think it's perhaps an open question on many microbes whether even those that perform, say, denitrification, actually need nitrate to survive or if they can get energy in other ways in a reef aquarium.

With this observation, we might conclude an aquarium does not need detectable nitrate, but (repeating what you already said) detectable nitrate is our way of observing the that aquarium organisms are getting enough inorganic nitrogen because we see a surplus as nitrate.

 

[ReefGeezer]

Is the lack of measurable nitrate a contributing factor to Dino outbreaks, or is it the lack of any nitrogen compounds in general?

 

[biom]

Lol you do realize who you’re talking to right? If you don’t agree with him it’s probably because you don’t understand what he’s talking about. I think you’re in over your head here bud.

Lol. I do, do you?

That sounds scary I used to live in a world where only one person was allowed to know everything and no one was supposed to disagree. We are all humans. Only ChatGPt is not (maybe) and even it gives wrong answers sometimes.
This is discussion forum that is why I am asking questions knowing most of the answers (and knowing what Randy will say). But “most” is the key word here because I already received valuable information papers and experience shared by other fellow reefers and I am very grateful for that.

 

[biom]

Is the lack of measurable nitrate a contributing factor to Dino outbreaks, or is it the lack of any nitrogen compounds in general?

That is very good question. From what we’ve heard so far the answer would be the lack of any nitrogen compounds but definitely deserves more research imo

 

[biom]

I was wondering this also. I was reading a few studies on nitrogen and phosphorus uptake rates in coralline and it mentioned the same thing. The gist was that ammonia was much more suitable for uptake and would be utilized before other nitrogen sources. I have also seen that mentioned in a few coral studies too.
I wonder if the aversion to ammonia dosing comes from the stigma surrounding ammonia levels in your tank through the inital nitrification cycle. "0 ammonia or no fish!"
I would think that a sufficient fish population being adequately fed would generate enough free ammonia to support the metabolic processes in the surrounding coral. But maybe it isnt sufficient? So the get as much as they can and then and only then turn to No3? Dunno. That is an interesting line of thought though.

In many cases the fish can not produce enough ammonia to cover all the demand. But I think that there’s big competition for ammonia and it is quite possible significant amounts of it to be oxidized to nitrate by the bacteria before coral. And the nitrate will appear on the test but this doesn’t mean that all the inhabitants received enough nitrogen in its most desirable form.

 

[Randy Holmes-Farley]

And the nitrate will appear on the test but this doesn’t mean that all the inhabitants received enough nitrogen in its most desirable form.

I agree with that, but I think there are many details related to this that are not understood.

I do think we really do not know if there is any "problem" with a coral not consuming it's preferred N source.

My preferred foods have almost no relationship to what is actually healthy for me, so I see no reason to assume the opposite is true for all other organisms .

There is even a question of WHY ammonia might be preferred.

In many parts of the ocean, ammonia is higher in concentration than nitrate. Since nitrogen in all forms is often in short supply, organisms may have evolved to go after the most readily available form. If nitrate were higher, would they not have evolved to go after nitrate?

Maybe corals even adapt to "prefer" nitrate if it is more available than ammonia. I've never seen a long term study of the preference issue for corals.

I understand that ammonia takes less energy to use for synthesis of biomolecules, but that is not itself evidence of whether or why one N source is preferred to another since many other aspects come into play (availability, uptake transport ease, internal toxicity, etc.).

Thus, I am cautions in interpreting preference studies as indicating that one is better than another.

I do recognize that there are some oxidative stress studies that suggest elevated ammonia reduces internal oxidative stress while elevated nitrate enhances it. I do not know how important that aspect is in a typical reef aquarium, but it might be a reason to dose ammonia over nitrate when N is low.

In general, I do agree that ammonia dosing has great potential to be different than nitrate dosing, but there's not yet much evidence to show what the benefit(s) may be, or logistically how one best controls and optimizes it.

There are far fewer studies of organic N dosing to corals, but I also think it has significant potential, coupled with the same control issues as ammonia dosing.

 

[Randy Holmes-Farley]

Is the lack of measurable nitrate a contributing factor to Dino outbreaks, or is it the lack of any nitrogen compounds in general?

IMO, it is likely lack of sufficient nutrients available to whatever is competing with the dinos, and what that may be could vary from tank to tank, but is likely to include all bioavailable N forms.

Example, zeovit ULNS systems not having big dino problems since N is added in other ways.

 

[Randy Holmes-Farley]

That sounds scary I used to live in a world where only one person was allowed to know everything and no one was supposed to disagree.

FWIW, polite scientific-based disagreement is always encouraged here.

 

[Randy Holmes-Farley]

With this observation, we might conclude an aquarium does not need detectable nitrate, but (repeating what you already said) detectable nitrate is our way of observing the that aquarium organisms are getting enough inorganic nitrogen because we see a surplus as nitrate.

Yes.

 

[biom]

IMO, it is likely lack of sufficient nutrients available to whatever is competing with the dinos, and what that may be could vary from tank to tank, but is likely to include all bioavailable N forms.

Example, zeovit ULNS systems not having big dino problems since N is added in other ways.

Zeovit is actually very good example of dosing N in form of ammonium and amino acids over nitrates, with the specifics - part of the ammonium is absorbed back by the zeolites.
For the dino problem we should not forget Zeovit is adding some elements for controlling coral symbiont dinoflagellates density (copper for ex) which could possibly effect free living dinoflagellates in the aquarium.

I also see the disadvantages of dosing ammonium - it should be done on a daily basis in small doses and in long term will resulted in raising nitrate in the aquarium water unless the one is running zeolites which can adsorb excess ammonium.

 

[vahegan]

No. Corals prefer Dissolved Organic Nitragen (amino acids and urea) and the Dissolved Inorganic Nitrogen form ammonia over nitrate.

IMO, it is likely lack of sufficient nutrients available to whatever is competing with the dinos, and what that may be could vary from tank to tank, but is likely to include all bioavailable N forms.

I was thinking along the same lines, and have experimented a bit on an [almost] fishless system (a 250l tank with one small clownfish). I have tried using nitrate, urea, and even aminos as the main nitrogen source. Dosing urea gives a slightly better result than adding nitrate directly, but it does not stay in the water column for long as, in addition to corals, there are numerous starving competitors - mostly bacteria. Therefore it is best to use continuous dosing or at least to dose it multiple times throughout the day. Whether there is a difference in dosing during the light hours only is still an open question for me. The same applies to dosing aminos. I have used a DIY mix (actually, I am working on an article on this) with multiple aminos in the same proportion as found in coral tissue (based on the data from various scientific papers). Dosing aminos gives very good results, but requires caution. I started low, and all was fine, but when I have increased the amount to be the only nitrogen source in the amounts that are daily consumed by my system, in about a week or two, it resulted in a severe dino outbreak which then took me months to cure. Therefore I believe that providing all the required nitrogen in the most valuable form is not the best solution. Adding Nitrate is safest and can be used as "insurance policy" as someone stated in this thread - to make sure you always have some nitrogen available, if someone needs it badly (but in this form it has a higher cost for the consumers to adopt it). I believe that it is a very good idea to supplement nitrate with both urea and aminos in that daily dose - but the best proportion is yet to be determined.

 

[Dan_P]

Zeovit is actually very good example of dosing N in form of ammonium and amino acids over nitrates, with the specifics - part of the ammonium is absorbed back by the zeolites.
For the dino problem we should not forget Zeovit is adding some elements for controlling coral symbiont dinoflagellates density (copper for ex) which could possibly effect free living dinoflagellates in the aquarium.

I also see the disadvantages of dosing ammonium - it should be done on a daily basis in small doses and in long term will resulted in raising nitrate in the aquarium water unless the one is running zeolites which can adsorb excess ammonium.

Just curious. Has anyone measured the amount of ammonia adsorbed by zeolites in saltwater?

 

[Kato]

I agree with all of this. And perhaps we can put the 'must have 5 nitrate or above' thing to rest.

It's interesting, as I saw a video where WWC said their corals did 'much better' at 25 nitrates. Further up it was mentioned that just because you measure some nitrate, then it doesn't mean that _nitrogen_ was available to all organisms when in the form of ammonia. I agree with that as well. One can argue that higher nitrates makes it more likely ammonia was available in a longer period of time.

In the end, adding more fish who excrete ammonia constantly seems to be the best way to feed the corals (vs dosing small amounts of ammonia over longer periods of time). Also got some fish to look at then. Though I use a combination of fish and dosing.

And my personal opinion and experience is Dinos have nothing to do with low Nitrate. Nitrogen, yes. Hence in my experience dosing nitrate does little for Dinos. Having more fish does. A new tank also often has less fish. Perhaps a good experiement with a dry-rock sterile tank is to dose ammonia from the get go as more fish likely can't be easily added quickly. Would also explain why real live rock tanks does better here initially. More die-off. Would also explain why Dinos are rarely an issue when you move an established tank to a new one, as you move the fish immediately as well in one go, even when replacing 100% of the water.

 

[Randy Holmes-Farley]

Just curious. Has anyone measured the amount of ammonia adsorbed by zeolites in saltwater?

It is known that clinoptilolite (a particular zeolite) will bind ammonia and that the ammonia bound can be displaced by salt. Thus I expect the amount bound in seawater is pretty low. We do not know what zeolite zeovit uses, or if it binds any ammonia (at least not that I have seen).

IMO, some of the zeovit ideas around ammonia are not logical. For years folks claimed the ammonia binding helped bacteria on the zeolite take up that ammonia, but that is not sensible since the zeolite does not attract ammonia toward the zeolite, but rather once ammonia is right adjacent to the zeolite pore opening and it drifts into the pore, the zeolite grabs and holds it, making bacteria getting it less likely, not more likely.

 

[Randy Holmes-Farley]

Zeovit is actually very good example of dosing N in form of ammonium and amino acids over nitrates, with the specifics - part of the ammonium is absorbed back by the zeolites.

I do not know if there is any significant ammonia binding, or if there is, how reversible it is on zeolites that have been in the water for a while and may be coated with organics and bacteria that may tend to plug the pores, but it is at least not impossible that a material might function to moderate changes in ammonia up or down just like calcium carbonate surfaces tend to moderate the up and down changes in phosphate.

That could be an advantage if dosing ammonia, at least if you are not otherwise able to measure and control concentrations well.

I do not see how a zeolite can be an ongoing sink for ammonia, however, any more than GFO can be an ongoing sink for phosphate, and would need to be replaced periodically if one wanted an ongoing ammonia sink effect.

 

[Randy Holmes-Farley]

And perhaps we can put the 'must have 5 nitrate or above' thing to rest.

Well, it is inherently true that the must have thought is untrue since it is not true in the ocean where all of our organisms thrive, but that does not mean it isn't a best practice for a typical reef tank.

 

[Randy Holmes-Farley]

I was thinking along the same lines, and have experimented a bit on an [almost] fishless system (a 250l tank with one small clownfish). I have tried using nitrate, urea, and even aminos as the main nitrogen source. Dosing urea gives a slightly better result than adding nitrate directly, but it does not stay in the water column for long as, in addition to corals, there are numerous starving competitors - mostly bacteria. Therefore it is best to use continuous dosing or at least to dose it multiple times throughout the day. Whether there is a difference in dosing during the light hours only is still an open question for me. The same applies to dosing aminos. I have used a DIY mix (actually, I am working on an article on this) with multiple aminos in the same proportion as found in coral tissue (based on the data from various scientific papers). Dosing aminos gives very good results, but requires caution. I started low, and all was fine, but when I have increased the amount to be the only nitrogen source in the amounts that are daily consumed by my system, in about a week or two, it resulted in a severe dino outbreak which then took me months to cure. Therefore I believe that providing all the required nitrogen in the most valuable form is not the best solution. Adding Nitrate is safest and can be used as "insurance policy" as someone stated in this thread - to make sure you always have some nitrogen available, if someone needs it badly (but in this form it has a higher cost for the consumers to adopt it). I believe that it is a very good idea to supplement nitrate with both urea and aminos in that daily dose - but the best proportion is yet to be determined.

I can certainly see how too much amino acid dosing could be an issue since amino acids are very useful for microorganisms to grow rapidly.

What did you find was different dosing urea than nitrate, and how did you decide how much urea to dose?

 

[Hans-Werner]

The most up-to-date, complete and conclusive work on this theme I have read is the dissertation of Shantz from 2016.

The figures in the link to another thread on this theme are taken from there

I think we agree that taking a coral from a reef and putting it in a reef tank will not alter its physiology.

Figure 2.1 – Cumulative effect sizes for coral calcification rates in response to enrichment with
nitrogen (N), phosphorus (P) or joint nitrogen and phosphorus (N + P). Responses are shown for:
(a) all corals, (b) branching corals, (c) mounding corals, (d) Acropora spp., and (e) Porites spp.
Data are means ± 95% confidence intervals. Numbers in parenthesis indicate the number of
experiments used to calculate effect sizes.

Figure 2.2 – Cumulative effect sizes of nutrient enrichment on different metrics of photobiology of
corals: (a) the density of chlorophyll a within individual Symbiodinium, (b) the density of
Symbiodinium within corals, (c) the density of chlorophyll a per area of coral, and (d) gross
photosynthesis. Statistics as in Fig. 2.1

Figure 2.4 – Cumulative effect sizes for the impact of ammonium or nitrate on: (a) the calcification
rates of corals, (b) the concentration of chlorophyll a within Symbiodinium, and (c) the density
of Symbiodinium in coral tissue. Statistics as in Fig. 1

From Andrew A. Shantz, Dissertation, 2016

I think nitrate in moderate concentrations is quite harmless as long as the corals don't have to make use of it.

My first experience with nitrate dosing was very bad. Somewhen in the 90s I worked at an public museum and aquarium. Two or three weeks before I left for holidays I decided to change the nitrogen dosing from urea to an equivalent (regarding nitrogen) dose of nitrate. I expected to see it at once if there would be a problem. No problem until I left for holidays. After I returned I found large parts of a plating Montipora burnt and dead and most of the other parts bleached. After changing back to urea the surviving parts gained back color and started to grow again. Since then I refrain from dosing nitrate only.

This is what oxidative stress from reactive oxygen species (ROS) means.

 

[Kato]

Well, it is inherently true that the must have thought is untrue since it is not true in the ocean where all of our organisms thrive, but that does not mean it isn't a best practice for a typical reef tank.

Fair, I agree it's certainly the easiest to communicate to a newer reefer and be at least somewhat sure stuff is going in. But would be good to move the discussion forward as we do here. I wish BRS or someone with access to a fair amount of identical tanks would do some experiments here. Especially around dinos and new sterile tanks

 

[Dennis Cartier]

Fair, I agree it's certainly the easiest to communicate to a newer reefer and be at least somewhat sure stuff is going in. But would be good to move the discussion forward as we do here. I wish BRS or someone with access to a fair amount of identical tanks would do some experiments here. Especially around dinos and new sterile tanks

You can glean a bit of what you are asking about, dinos in new sterile tanks, in the BRS Biome Cycling experiment. The final video, where they discuss conclusions is probably the best one for the topic you are interested in.