Ammonia is our Friend 2: Article Outline

[Randy Holmes-Farley]

Since this article and what exactly gets incorporated into it is still evolving, I thought I'd open it up for discussion of things I should include that are not mentioned or things that I mention that should not be included.

There will be lots of standard ammonia science stuff as well, such as ammonia in the ocean, free vs total ammonia, testing methods and complexities, etc.

Here's the start of the article:

Ammonia is Our Friend

By Randy Holmes-Farley​

Yes, I know the title is provocative, and likely goes against much of what you read and hear in the reef aquarium hobby. I believe, however, that the hobby may have been harmed by the continual vilification of ammonia as something that one wants to reduce as much as possible. Products and procedures to keep driving it down may well be detrimental in many reef tanks.

This bulleted summary contains the points that I make in detail in the subsequent sections of this article along with some basic science about ammonia. They are presented in a logical order of progression, but if you already know you agree with certain points, it may not be needed to read those sections to get a complete story.

1. While ammonia is toxic at very high levels, the levels needed to be lethal to a marine fish are higher than many people think. I’ve not seen any study in the literature that shows an LC50 (half of fish die) in less than 15 ppm total ammonia in seawater over 4 days or more of exposure at normal pH.

2. Sublethal toxic effects of ammonia, such as gill lesions observed by histopathology, do not seem to become significant until levels reach 5-10 ppm total ammonia at pH 8.1.

3. The toxicity of ammonia is a function of pH. At pH 8.5, toxic effects kick in at ammonia levels 2.5x lower than at pH 8.1. Likewise, at pH 7.8, it takes twice as much ammonia to be toxic as at pH 8.1. In a situation where ammonia might well reach toxic levels, such as a shipping bag, raising pH in the bag should not be a goal.

4. Toxic levels of ammonia are just not reached in typical operating reef aquaria. Seeing a measured value of 0.25 ppm, whether real or test error, is not a concern. It may be a benefit.

5. Chemical methods to control or detoxify ammonia in marine systems at doses recommended are generally ineffective at impacting ammonia, despite folks thinking they were effective. If you believe that 2 ppm ammonia will kill a fish, and you add an ammonia detoxifier and it survives, you may falsely conclude it worked, as opposed to you misunderstood how toxic ammonia was.

6. Corals demonstrate a preference for obtaining the N (nitrogen) they need from ammonia over nitrate when both are available. Organisms using nitrate as an N source need to spend extra energy to convert the nitrate to ammonia before use.

7. Continually driving ammonia down in a reef tank may be making it unnecessarily difficult for corals to easily obtain the nitrogen they need. Actions such as providing media designed for nitrifiers or adding nitrifying bacteria on a regular basis may thus be doing more harm than good.

8. Reef aquaria where N is in short supply may benefit from dosing ammonia, and that benefit may be greater than dosing nitrate. Ammonium bicarbonate is a good source of ammonia as it is inexpensive and readily available in food grade purity.

9. While measuring a detectable level of nitrate in a reef aquarium can be very useful to ensure there is some source of N available for corals, one should not assume that corals are primarily using that source since there are other sources that they may prefer to use.

10. “Cycling” a new reef tank with nitrifying bacteria is just one way to start a tank, and reefers should not simply accept the idea that it is the only way. It may be a fast way to add fish, but perhaps reefers should at least be aware of other options. There will be no stopping nitrifying bacteria from naturally growing in any reef system, but a system where consumption of N is the focus (corals, macroalgae, anemones etc.) as opposed to producers (fish and anything else fed outside food) may not require the addition of bacteria or the time spent waiting for them to develop.

​

 

[Harpo]

Thanks Randy

 

[CHSUB]

Thanks, if there appears to be multiple source of N in a reef aquarium and generally most only test for no3 and conclude if 0 N is limited, when in reality N is available. Would this also apply to po4 or when po4 is 0 it is limited?

 

[Randy Holmes-Farley]

Thanks, if there appears to be multiple source of N in a reef aquarium and generally most only test for no3 and conclude if 0 N is limited, when in reality N is available. Would this also apply to po4 or when po4 is 0 it is limited?

Yes, it can. Dissolved and particulate organics often contain phosphate as well. Thus, one must be very careful in extrapolating one reef tank thriving at undetectable nitrate and phosphate to any other tank that may have different levels of these other sources.

 

[SDchris]

6. Corals demonstrate a preference for obtaining the N (nitrogen) they need from ammonia over nitrate when both are available. Organisms using nitrate as an N source need to spend extra energy to convert the nitrate to ammonia before use.

Maybe beyond the scope of the article, but was thinking about why nitrate tends to reduce calcification. Is the main reason extra energy expenditure or free radicals produced? Was looking for a paper (unsuccessfully) that compared light/dark calcification rates under nitrate enrichment. Maybe such a paper would help clear that up? There are papers suggesting nitrate enrichment causes bleaching during thermal stress when ammonium dose not.

8. Reef aquaria where N is in short supply may benefit from dosing ammonia, and that benefit may be greater than dosing nitrate. Ammonium bicarbonate is a good source of ammonia as it is inexpensive and readily available in food grade purity.

If the above oxidative stress is true, then that might cause confusion regarding N limitation. Bleaching might be interpreted as being starved, and the addition of ammonium might alter the bleaching status, giving the false appearance that it was N limitation.

 

[Randy Holmes-Farley]

Maybe beyond the scope of the article, but was thinking about why nitrate tends to reduce calcification.

What is the evidence it does?

If the above oxidative stress is true, then that might cause confusion regarding N limitation. Bleaching might be interpreted as being starved, and the addition of ammonium might alter the bleaching status, giving the false appearance that it was N limitation.

Richard Ross' tank has had nitrate in the 50-100 ppm range for a long time, and his corals have been thriving. But neither he nor any other reefer knows whether corals are actually using that nitrate.

 

[SDchris]

What is the evidence it does?

In respect to ammonia vs nitrate.
From this paper posted in the other thread. p22:
The Individual and Interactive Effects of Nitrogen and Phosphorus Enrichment on Coral Reefs

Our analyses show that nitrate tends to slow coral growth while ammonium has little effect

Although this paper showed no statistical difference in weight, however the linear extension data, how we interpret growth, also suggests ammonium over nitrate. See Table 5.
Bicarbonate addition promotes coral growth.

Richard Ross' tank has had nitrate in the 50-100 ppm range for a long time, and his corals have been thriving. But neither he nor any other reefer knows whether corals are actually using that nitrate.

I think 'thriving' is rather subjective, but that is getting off topic.
The original point is that in a least the small number of tanks I'm familiar with, the acropora type coral where heavily pigmented (zoox), especially the under side of the branches, leading to a conclusion that these coral where not N limited. Maybe limited as far as nutrient ratios or N type, but not N in general.
While I believe when the owners of these tanks describe an increase in growth (linear extension) after ammonium supplementation, I have a hard time believing they are N limited.

 

[Koty]

What about amino acids as an optional additive instead of ammonia . that covers “too low” nitrates and at the same time directly feeds corals with protein constituents. This is in light of the fact that corals have effective uptake mechanisms. Only issue is the cost and the lack of knowledge which AAs are essential in the sense that corals cannot synthesize (maybe there aren’t any as their symbionts produce all of them).

 

[vahegan]

What about amino acids as an optional additive instead of ammonia . that covers “too low” nitrates and at the same time directly feeds corals with protein constituents. This is in light of the fact that corals have effective uptake mechanisms. Only issue is the cost and the lack of knowledge which AAs are essential in the sense that corals cannot synthesize (maybe there aren’t any as their symbionts produce all of them).

I have tried exactly that: using amino acids as the main nitrogen source. In regard with cost, I used AA powders from Amazon, which come very cheaply. And for which AA to use in the mix, I used scientific data on AA composition of scleractinian corals, and of various organisms which are coral food source. However, dosing such high amounts of AA in the reef tank has resulted in a dino bloom. It may not have been the main cause, or may be unrelated: as I do not have any scientific methods to prove that, but this is what I faced...

 

[Koty]

Although I am a scientist I went with commercial TM AAs. I know there are other compounds in their mix. My corals are generally looking good and growing. Having many fish 20/110g I still get 0 nitrate with high phosphate. I also have a major hair algae problem. After some time I bought 5 liters of this TM Amino organic so I have to keep telling myself that it works

 

[vahegan]

Although I am a scientist I went with commercial TM AAs. I know there are other compounds in their mix. My corals are generally looking good and growing. Having many fish 20/110g I still get 0 nitrate with high phosphate. I also have a major hair algae problem. After some time I bought 5 liters of this TM Amino organic so I have to keep telling myself that it works

I was trying to achieve 2-5ppm nitrate in a 250l tank with just 2 medium fish with light feeding, using only AA. It can be very hard to do that with commercial mixes, even if buying in 5 liter piles (and the cost is still very high). I did not see any issues when the dose was relatively low (i.e. until I was seeing significant measurable nitrate in the tank)

 

[vahegan]

As for commercial mixes, I am trying to never add anything to the tank, unless the label clearly specifies what is in there, and in what quantity. Because otherwise, it often appears to be either snake oil, or something that might have detrimental effect on the tank.

 

[Koty]

Agree, yet at some point you cannot assume that everything is SO. I trust HV Balling from Tropic Marine because he contributed a lot to the hobby and he is always there to address issues online. The other guy… from TM does not always know 100 % what he is talking about. They don’t fully disclose what are their ingredients but I have a general idea. What would have been nice if they shared the experimental data that demonstrate the functions of their products.

 

[Lasse]

the acropora type coral where heavily pigmented (zoox), especially the under side of the branches, leading to a conclusion that these coral where not N limited.

Or its a sign of the opposite - the coral animal increasing the number of zoox in order to have a greater chance of capturing the few desired molecules.

According to the original post

1) I have trouble with using LC50 as an argue for environmental water parameters when holding fish/animals in capture both according fish farms and for my own pleasure. LC0 is my goal according to environmental factors affecting my husbandry. I chose that before accelerated growth of whatever.

I have also invertebrates in my aquarium and a recent review highlight that they are the more sensitive than vertebrates. I can´t access the full article but here is a summary of the article. You may have access to it

With thais said - I´m not afraid of NH3/NH4 (total ammonia) concentration peaks up to around 0.3 - 0.5.

2) There is other sublethal effects reported - including oxidative stress - than gill damage

3) Important to realize that in a normal reef aquarium pH swing a lot. The main production of NH3/NH4 in a mature reef aquarium is - IMO - bacterial mineralisation of organic N. It happens 7/24. The consumption of NH3/NH4 is mainly - as I know - during the light period. The transformation of NH3/NH4 into NO3 happens 7/24.

4) Agree

5) Agree

6) Still have problem with the word preference because it indicate that they have an own will. However, I agree that regardless of will - NH4-N is probably used before NO3-N if both are present.

7) IMO and IME - the best reef aquarium I have run has been equipped with specially designed nitrification filters.

I agree that it is no need of adding extra nitrifying bacteria when its up and running and the nitrification cycle is already established

8,9 and 10 I agree

Sincerely Lasse

 

[Hans-Werner]

Richard Ross' tank has had nitrate in the 50-100 ppm range for a long time, and his corals have been thriving. But neither he nor any other reefer knows whether corals are actually using that nitrate.

Yes, I think I also read about the inhibition of calcification by nitrate, maybe again Wiedenmann is one of the authors.

The difference to reef tanks with high nitrate concentration is the precondition.

The scientific research is done with NSW low in N. After nitrate is added and while the trial runs the corals really make use of the nitrate and assimilate it. The assimilation is the process that causes the damage and inhibition, not the mere presence of nitrate.

In most reef tanks with some fish, corals may never make use of nitrate or not to an extend where it does visibly harm corals. If corals don't assimilate nitrate it is just another ion in the water. Well it is an oxidant, but othwise the corals and nitrate are passive towards each other. This is a central point of my theory on nitrate I have in mind. So I never understood the "nitrate cult".

But even if the corals assimilate some of the nitrate, the availability of ammonium and phosphate to the corals helps repair the damage done by nitrate, according to Shantz' Dissertation.

And finally there is one more possibility based on the biochemistry of the specific coral species or coral clone: There may be corals that do not express nitrate reductase under most conditions or may be even nitrate reductase defective mutants. These corals could be especially hard in reef tanks. Just a theory.

However this is not only a mere theory: Under conditions of global warming and ocean eutrophication, nitrate reductase defective mutants could have an evolutionary advantage, at least locally or regionally. They would not be able to make any use of nitrate and in this way may acquire less nitrogen, but on the other side they would be much less susceptible to bleaching under thermal stress, and in eutrophic water the necessicity to acquire N from nitrate may be reduced anyways.

 

[Lasse]

From this article

We exposed 10 replicate colonies for each of the 9 hard and one soft coral species to either replete or limiting concentrations of nitrate and phosphate for more than 6.5 months (Supplementary Fig. 1 and Methods).

They result strongly indicate that at least the tested species in fact can use NO3-N as its inorganic N source. This is the longest controlled test run I have seen in aquarium like situations in all scientific paper I have seen. They also knit their observation to natural ecosystem that have elevated NO3 concentrations.

Further on - my bold

To test our hypothesis that the N and P responsible for sustaining host growth in our experiments was supplied by the symbionts, we conducted a stable isotope labelling experiment. Three coral species (Euphyllia paradivisa, A. polystoma and S. pistillata) were exposed to daily 2-h pulses of controlled amounts of 15N-enriched NO3 and PO4 for 5 days per week over a period of more than 8 months in separate compartments of the otherwise nutrient-limited experimental system (Supplementary Fig. 1 and Methods). Corals exposed to dissolved inorganic nutrient pulses grew about 3.7-fold more than the controls (Fig. 2a). By the end of our experiments, the 15N values (δ15N) for both symbionts and host tissue were more than 200-fold higher than those of the controls (Fig. 2b). The significant enrichment of 15N in the host tissue provides direct evidence that the gain in host N was achieved through the uptake of dissolved 15NO3 by the symbiont. Over the duration of the experiment, each colony took up on average around 121 µmol N and 5.7 µmol P from the water in dissolved inorganic form (Fig. 2c,d).

Sincerely Lasse

 

[Hans-Werner]

Articles on growth reduction with nitrate additions are Christine Ferrier-Pagès et al. and Marubini and Atkinson for example. Marubini is commenting under which conditions nitrate may reduce growth.

This one compares health and mortality effects of different nitrate concentrations at different salinities to Acropora sp..

 

[SDchris]

From this article

What really stands out from that article is how little N is required.

 

[brandon429]

That's a darn good working summary I'll read that article 4x over to absorb it.

Point #4 impacts what I spend my time doing the most. Can't wait to see that expanded

*to pick .25 as the arbitrary cutoff is interesting. That must be done subjectively, based on patterns from post feedback over the years from the #1 test kit people use in the hobby to discern ammonia status: api

I'd raise it to .5 to cover the next widest misinterpretion range, nobody has .5 stuck cycles either.

 

[Reefahholic]

I have tried exactly that: using amino acids as the main nitrogen source. In regard with cost, I used AA powders from Amazon, which come very cheaply. And for which AA to use in the mix, I used scientific data on AA composition of scleractinian corals, and of various organisms which are coral food source. However, dosing such high amounts of AA in the reef tank has resulted in a dino bloom. It may not have been the main cause, or may be unrelated: as I do not have any scientific methods to prove that, but this is what I faced...

Amino’s always seem to promote or encourage undesirables if you dose too much or dose long-term. They’re beneficial for the corals it seems, but too much trouble for everything else so I rarely dose AA’s anymore. When I do, it’s short-term.