Do we need Nitrate in a reef tank?

[InvictusReef]

Thanks, will take a look.

It is more than 25 years ago and now I work for a company. I don't recall exactly the dosing at that time. I recall that I tried N : P ratios between ca. 12 : 1 and 25 : 1, around the Redfield ratio, and around 15 : 1 caused the least cyanobacteria growth.

If I recall it right my approach was not too different from yours, I wanted to find some nitrate to see it was enough nutrients.

I came to urea because finally it is a kind of non-toxic form of ammonium. And I already knew at that time that urea is involved in many calcification processes.

Before doing the N and P trials I had developed a trace elements formula putting the trace elements into a ratio to calcium and alkalinity supply. From this I knew that urease is a nickel enzyme that is involved in calcification processes by catalyzing the hydrolysis from urea to ammonia and CO2. So why not get both, improved calcification and nitrogen supply, with one compound?

I think especially when dosing amino acids you have to take care of phosphate. Finally amino acids are ammonium + organic carbon dosing at the same time.

The dosing of urea is also not as simple as it may look at first glance. The processing and metabolization of urea by corals and other organisms depends on the trace element nickel which activates the urease, the urea hydrolyzing enzym. Natural levels and even more depleted levels of nickel may activate urease incompletely and insufficiently.

It’s a really good question but I can tell you for sure that I am a Goni collector, and when I ran ULN, they were furious they never wanted to open. I thought I was losing all of them. I started dozing, bright, well, neo nitro and within a matter of 24 hours they started to open inside of the week. They were fully expand it again so now I run my tank at 10 PPM and everybody is happy.

 

[taricha]

why are there not a large number of reports of negative results when initiating nitrate dosing?

Clearly the nitrate is being consumed in most cases. What visible harms are happening?

I guess I do not see the trend that dosing nitrate causes issues.

I'll lay out one scenario where we do see recurring issues with NO3 dosing (though the form of N being NO3 isn't likely the problem).

Person has dinos and tests to find zero/zero NO3/PO4. So they take advice to elevate those by dosing. Problem is that they can't immediately get a trusted PO4 source, but can get KNO3 at hardware store. So they start dosing NO3, while waiting on their PO4 additive to ship. Or PO4 adsorbs to surfaces and is hard to get measurable, while NO3 gets elevated. Either leads to weeks of higher NO3 with zero PO4 in a tank that was previously zero on both.

This pattern has led to coral losses and bleaching even in tough corals like montipora etc.

The literature explanation is that corals can handle N starvation with some P around, but N elevation with P starvation is more stressful.
Impacts of nutrient enrichment on coral reefs: new perspectives and implications for coastal management and reef survival
".. (c) Undersupply of growing zooxanthellae populations with P or other essential nutrients including iron/trace elements (*) can result in nutrient starvation of the algae. P starvation, can be induced by the transition of zooxanthellae from a nutrient-limited to a nutrient starved state due to an increased cellular P demand caused by growth rates being accelerated by elevated nitrogen supply. Under this condition, zooxanthellae replace phospholipids [phosphatidylglycerol, PG] by sulfolipids [sulphoquinovosyldiacylglycerol, SQDG]. P starvation reduces the photosynthetic capacity (Fv/Fm < 0.5) and renders the corals susceptible to heat/light stress. Alternatively, P starvation might result when zooxanthellae growing under nutrient replete conditions are deprived of P while nitrogen levels remain high."
(figure 2 has nice pics of montipora under various N/P combos.)


Phosphate deficiency promotes coral bleaching and is reflected by the ultrastructure of symbiotic dinoflagellates
"...We argue, however, that the direct negative effects on the symbiosis are not necessarily caused by the nutrient enrichment itself but by the phosphorus starvation of the algal symbionts that can be caused by skewed nitrogen (N) to phosphorus (P) ratios. We exposed corals to imbalanced N-P ratios in long-term experiments and found that the undersupply of phosphate severely disturbed the symbiosis, indicated by the loss of coral biomass, malfunctioning of algal photosynthesis and bleaching of the corals. In contrast, the corals tolerated an undersupply with nitrogen at high phosphate concentrations without negative effects on symbiont photosynthesis, suggesting a better adaptation to nitrogen limitation. ...Notably, high N-P ratios in the water were clearly identified by the accumulation of uric acid crystals."
(figure 1 for pics of euphyllia under various N/P combos.)


So now we try to say if you are N/P zero/zero make sure to get the PO4 measurable first before adding NO3.

again, not really NO3 specific - but it does cover bad outcomes repeatedly seen with NO3 dosing.

 

[Hans-Werner]

It’s a really good question but I can tell you for sure that I am a Goni collector, and when I ran ULN, they were furious they never wanted to open. I thought I was losing all of them. I started dozing, bright, well, neo nitro and within a matter of 24 hours they started to open inside of the week. They were fully expand it again so now I run my tank at 10 PPM and everybody is happy.

Please note: I never said oberservations are not correct, I am only saying, the explanations are not correct. This is also the reason why results are not reproducible as they should be.

I am only saying I am sure nitrate doesn't make sense as a nutrient above 2 ppm concentration. Most likely you have to look for other explanations for your observations, otherwise you will never get an idea about the real processes and interactions that take place in reef aquaria and maybe in reefs.

There is a lot of things that could have happened.

Brightwell doesn't tell exactly what kind of nitrogen salts they use. Is there something else inside except nitrate? Maybe your corals have made use of the other available nitrogen compounds and didn't even care about the added nitrate. Nitrate did only act as a kind of marker you can easily test for.

Maybe you need some nitrate level in the tank to get other more reduced forms of nitrogen like ammonium or urea in concentrations sufficient for good coral growth. These reduced nitrogen compounds are products of bacterial and algal metabolism. Here the positive effect of nitrate is a secondary nutrient effect and could be replaced much easier by other available nitrogen compounds that get directly used by the corals.

Maybe the nitrate mainly acts as an oxidant and just prevents the dissolution of precipitated trace metals like iron or manganese that in some way interfere with the other nutrients and impair coral well-being in this way.

My favourite would be the last explanation, nitrate is an oxidant that prevents dissolution of some precipitated trace metals, most likely iron and manganese.

Then the correct explanation would be, that nitrate as an oxidant increases the precipitation of iron and manganese and keeps it oxidized and precipitated as long as the concentration is high enough. In this way high concentrations of precipitated iron and manganese accumulate in the bottom substrate. If nitate concentration drops to low concentrations, iron and manganese get reduced and dissolved in the bottom substrate and even get into the water by currents and diffusion. There they either form toxic concentrations or interfere with other trace metals or nutrients and this causes the observed negative effects.

 

[Randy Holmes-Farley]

So now we try to say if you are N/P zero/zero make sure to get the PO4 measurable first before adding NO3.

again, not really NO3 specific - but it does cover bad outcomes repeatedly seen with NO3 dosing.

Yes, that makes sense. Thanks.

I wonder if the same would apply to ammonia dosing?

 

[taricha]

Yes, that makes sense. Thanks.

I wonder if the same would apply to ammonia dosing?

I don't know. The research on corals suffering from elevated N while P was low seems to be mostly involving NO3 elevation.
It's worth asking if things would go better if the N input was ammonia instead.

 

[Dan_P]

I'll lay out one scenario where we do see recurring issues with NO3 dosing (though the form of N being NO3 isn't likely the problem).

Person has dinos and tests to find zero/zero NO3/PO4. So they take advice to elevate those by dosing. Problem is that they can't immediately get a trusted PO4 source, but can get KNO3 at hardware store. So they start dosing NO3, while waiting on their PO4 additive to ship. Or PO4 adsorbs to surfaces and is hard to get measurable, while NO3 gets elevated. Either leads to weeks of higher NO3 with zero PO4 in a tank that was previously zero on both.

This pattern has led to coral losses and bleaching even in tough corals like montipora etc.

The literature explanation is that corals can handle N starvation with some P around, but N elevation with P starvation is more stressful.
Impacts of nutrient enrichment on coral reefs: new perspectives and implications for coastal management and reef survival
".. (c) Undersupply of growing zooxanthellae populations with P or other essential nutrients including iron/trace elements (*) can result in nutrient starvation of the algae. P starvation, can be induced by the transition of zooxanthellae from a nutrient-limited to a nutrient starved state due to an increased cellular P demand caused by growth rates being accelerated by elevated nitrogen supply. Under this condition, zooxanthellae replace phospholipids [phosphatidylglycerol, PG] by sulfolipids [sulphoquinovosyldiacylglycerol, SQDG]. P starvation reduces the photosynthetic capacity (Fv/Fm < 0.5) and renders the corals susceptible to heat/light stress. Alternatively, P starvation might result when zooxanthellae growing under nutrient replete conditions are deprived of P while nitrogen levels remain high."
(figure 2 has nice pics of montipora under various N/P combos.)


Phosphate deficiency promotes coral bleaching and is reflected by the ultrastructure of symbiotic dinoflagellates
"...We argue, however, that the direct negative effects on the symbiosis are not necessarily caused by the nutrient enrichment itself but by the phosphorus starvation of the algal symbionts that can be caused by skewed nitrogen (N) to phosphorus (P) ratios. We exposed corals to imbalanced N-P ratios in long-term experiments and found that the undersupply of phosphate severely disturbed the symbiosis, indicated by the loss of coral biomass, malfunctioning of algal photosynthesis and bleaching of the corals. In contrast, the corals tolerated an undersupply with nitrogen at high phosphate concentrations without negative effects on symbiont photosynthesis, suggesting a better adaptation to nitrogen limitation. ...Notably, high N-P ratios in the water were clearly identified by the accumulation of uric acid crystals."
(figure 1 for pics of euphyllia under various N/P combos.)


So now we try to say if you are N/P zero/zero make sure to get the PO4 measurable first before adding NO3.

again, not really NO3 specific - but it does cover bad outcomes repeatedly seen with NO3 dosing.

If I am doing the math correctly on the repot’s concentrations, 0.018 mg/L is low and 0.36 mg/L is high PO4. Seems like the 0.03 ppm recommendation for PO4 might be a concern for new aquaria which could be experiencing high nitrate concentrations. Am I thinking about this correctly?

 

[GARRIGA]

No nitrates in NSW but I guess fish constantly pooping and might be why all get fed. Yet we strive to remove every strand of poop. Perhaps one day we stop that nonsense and just have efficient filtration that converts that poop into an available form for all to use.

 

[jda]

Just to be clear, you are talking about no3 and po4 ratios disrupting cellular functions moreso than as nutrients?

If so, then would nitrogen via ammonia or even nitrite not have the same outcome?

 

[Hans-Werner]

No nitrates in NSW but I guess fish constantly pooping and might be why all get fed. Yet we strive to remove every strand of poop. Perhaps one day we stop that nonsense and just have efficient filtration that converts that poop into an available form for all to use.

Yes, but poop is mainly a source of particulate phosphate, the remnants of crustacean shells, fish bones and scales, bacteria and other microorganisms. Fish excrete nitrogen mainly as dissolved ammonia through their gills.

Fish provide both, but phosphate is mainly excreted in particulate form while nitrogen is excreted as ammonia in dissolved form.

Just to be clear, you are talking about no3 and po4 ratios disrupting cellular functions moreso than as nutrients?

If so, then would nitrogen via ammonia or even nitrite not have the same outcome?

The assimilation (incorporation) of nitrogen compounds is very different between ammonium/ammonia and nitrate. While ammonia is just detoxified by binding to glutamate to form glutamin, nitrate assimilation produces reactive oxygen species ROS that may damage cells if not detoxified fast enough.

 

[GARRIGA]

Yes, but poop is mainly a source of particulate phosphate, the remnants of crustacean shells, fish bones and scales, bacteria and other microorganisms. Fish excrete nitrogen mainly as dissolved ammonia through their gills..

But doesn’t decomposition release those nutrients making them available to its inhabitants? Grasp that corals prefer particulate phosphate and why Tropic Marin now provides that option but was also under the assumption there’s other components as you mentioned that can only become accessible post decomposition bs direct consumption.

 

[jda]

While perhaps not enough, I have read a lot on the subject, although mostly with true coral (stonies). Orthophosphate (least preferred), polyphosphate (more preferred) and organically bound phosphate (best). With organically bound phosphate, think very small live things that the stonies can catch and assimilate through their slime coats - in our tanks, likely only bacteria. This is efficient for the stonies and they get to keep and use much of the building blocks and energy that they receive. This is NOT the same thing as attempted polyp digestion.

I have never seen any kind of suggestion that actual poop particles get assimilated by coral. I would like to read about this, if otherwise.

This was posted by Dr. RHF a while back... likely plenty of phosphate coming out of the gills too...

I am, as it happens, an expert on phosphate metabolism. I've studied it for more than 20 years, and have invented products that sell more than a billion dollars worth each year correcting hyperphosphatemia in people.

There is a flow chart in this link which shows the relative excretion of phosphate in urine (which is almost totally inorganic phosphate) and in feces (which is a combination of organic and inorganic phosphate).

https://www.inkling.com/read/medica...-2nd/chapter-52/calcium-and-phosphate-balance

The inorganic phosphate in urine excretion dominates, even if you ignore all of the inorganic phosphate in the feces. Then you seem to assume that all of that feces ends up in the substrate, which is utterly untrue. Other macroscopic creatures eat it, sometimes over and over. I had a kole tang that loved to eat my yellow tangs feces as fast is it came out. That drops the original phosphate ending up in feces by another factor of three. Each cycle drops it significantly.

 

[taricha]

If I am doing the math correctly on the repot’s concentrations, 0.018 mg/L is low and 0.36 mg/L is high PO4. Seems like the 0.03 ppm recommendation for PO4 might be a concern for new aquaria which could be experiencing high nitrate concentrations. Am I thinking about this correctly?

There's all sorts of fuzzly defined reasons why corals might do poorly in brand new tanks, but the scenario you suggest is at least a plausible common one.

If fishless cycling, some directions might have you end up adding in the ballpark of 6-10 PPM ammonia, so you can end up with quite high nitrate values and if you then target 0.03 PPM po4, that low target might be difficult to keep in the presence of that much nitrate. It could very easily stay stubbornly below the 0.03 ppm PO4 target and subject any new corals in that system to the conditions they found to be detrimental to corals.

Just to be clear, you are talking about no3 and po4 ratios disrupting cellular functions moreso than as nutrients?

If so, then would nitrogen via ammonia or even nitrite not have the same outcome?

The papers suggested the harm would occur regardless of the form of N, but since their experiments were with NO3, it's not totally clear that other forms of N addition would result in the same.
As others have noted, there's detailed differences in what happens to cells to get N inside depending on external form.
Add the layer of complexity that is coral+symbiont mechanics, and I have no idea what would happen without actually seeing experiments. People with decades of coral experience

 

[GARRIGA]

I have never seen any kind of suggestion that actual poop particles get assimilated by coral. I would like to read about this, if otherwise.

Phos-Feed | Produktinformationen

www.tropic-marin-smartinfo.com

Video explains the concept best and seems logical that in a low nutrient environment direct feeding how inhabitants get what they need vs reefers targeting a dilution utopia. Fish poop more valuable than gold yet we seek to remove every particle.

 

[Randy Holmes-Farley]

Phos-Feed | Produktinformationen

www.tropic-marin-smartinfo.com

Video explains the concept best and seems logical that in a low nutrient environment direct feeding how inhabitants get what they need vs reefers targeting a dilution utopia. Fish poop more valuable than gold yet we seek to remove every particle.

I think jda meant a study that literally showed that corals can take up fish poop particles.

 

[jda]

Thanks, but I meant more like science. I am not one to believe nearly anything that a retailer or manufacturer says about anything... like nothing. I am not saying that they are wrong, just that the long line of liars before them should make us all not want to believe them alone.

I am not denying that it can happen... I just read a lot and have never seen this. It is likely that I am dumb or not well-read enough.

 

[GARRIGA]

I think jda meant a study that literally showed that corals can take up fish poop particles.

Lou should be able to provide how Tropic Marin came to this conclusion and I'm providing a plausible path to obtaining that although I tend to believe what Lou promotes, within reason. This seems logical or at minimum supports how reef inhabitants needing certain nutrients might obtain that in a nutrient deprived environment. Feed was my original thought process although poop does seem to be utilized by many earth inhabitants and coral might be one of them. More food for thought than definitive conclusions.

 

[Randy Holmes-Farley]

This seems logical or at minimum supports how reef inhabitants needing certain nutrients might obtain that in a nutrient deprived environment.

In the ocean, they are known to feed on microorganisms such as zooplankton. They may well feed on other things such as fish poop, but one need not invoke it to live in a low nutrient environment.

 

[GARRIGA]

In the ocean, they are known to feed on microorganisms such as zooplankton. They may well feed on other things such as fish poop, but one need not invoke it to live in a low nutrient environment.

This is where my knowledge of corals is severely lacking and based purely on anecdotal theories and lack of experience since last I was involved in corals was the 90s and much has evolved since then where thought process being that lights the only concern with all else being as close to zero as possible. During my day, VHO was a big thing. Specifically nitrates and phosphates since ammonia and nitrites were not an issue. Then it evolved to needing a level of N and P although some of this leads me to believe more to avoid dinos or cyano vs the health of corals.

I've never had dinos, cyano now but only in low flow areas and that's quickly resolved. Been months since I've seen cyano and perhaps just maturing solved that. Run my test tank from bottomed out to dirty beyond reason. Currently letting it get dirty for my next experiment yet GHA refuses to show. Granted just fish because I'm focused on decomposition but I've eliminated concern for dinos or cyano in my unique system therefore these two issues aren't a concern.

This leaves the health of coral being affected by lack of nutrients for which some believe a constant influx of ammonium might resolve the N and Tropic Marin now suggest that particulates being the preferred mechanism of delivering P. One actually suggested dosing ammonium chloride which made sense. Day I solve my ph then I can start my own tests with corals which don't survive now but until then there's lots of contradictory data with some being supported by studies and others lacking them but still it does get bewildering and why I ask for patience because that not sounding logical tends to be hard for me to just accept.

My current belief being that overfed tanks that are overfiltered to the point that soluble nutrients are zero might be the best approach because that needed is constantly being introduced yet not allowed to linger which best replicates life on a reef where soluble nutrient are far below what is found in our tanks. Does this last paragraph have merit to the point that regardless whether supported by studies or anecdotal experience it just seems the most logical and simplest conclusion or are lights all that corals need? Last puts me back in the 80/90s where I started and was much less confused.

 

[jda]

Heavy feeding and heavy export of the backend is very much the goal, IMO. The backend being po4 and no3. This still leaves nitrogen in many forms like ammoni[a,um], nitrite and small organics - as well as a trace of no3. Phosphorous in the forms of metaphosphate and small organics - as well as a trace of po4. This keeps all of the seemingly preferred forms of building blocks around while taking away the ones that can build up and possibly cause cellular disruption.

Light is a topic that amazes me. Corals need light for energy through the zoox. Lots of people are all worried about dosing no3 and po4 thinking that they are coral "food" and all the while looking to see how low that they can keep PAR and spread for their corals. Counterproductive. This is another thread that would get 20 pages, but spectrum from about 350 to 850 from UV all the way through IR to move energy between all photosystems, create energy and also pigments (sunscreen type too) is a good idea for growth and color.

You need building blocks and energy. You don't need much phosphate or nitrate.

Some of the best tanks for many decades have been high import, high export and high throughput.

Forget about dinos or GHA for this discussion, IME. The main reason for them is uninhabited ground for the quicker squatters to settle... in our case, sterile rock and sand. Even a coating of film bacteria, coralline or the like can keep nearly anything from catching hold. These were nearly no issue when people used live rock since there was no undeveloped land... dinos in the sand for a quick ugly phase, for example. Hair can take over and spread and kill off the surrounding parcels, but it is not nearly as fast or voracious as settlement on sterile ground. The whole tie in with "nutrients" is mostly wrong, IMO, unless you want to talk about raising po4 and no3 to growth limit (poision) dinos, but this does not work well with GHA until you get higher levels.

 

[Sdot]

I think the question is too vague.

Having detectable nitrate assures there is sufficient N for organisms we keep, and many organisms can use it if they need to.

It does not mean that one must have nitrate if the other sources are sufficient, but since we do not measure these other sources, having it is an insurance policy, even if it it is not the primary form of N consumed.

Randy this is kinda the same between measuring alkalinity to determine how much "buffer" capacity a system has? Is that correct?