Why your aquarium needs nitrates (no3)?

[CHSUB]

The study above quotes the best research example of nitrate enrichment on coral calcification. It is definitive, absolutely, and without argument. Borneman and Sprung use this study specifically to explain nitrate effects on corals and aquariums in their books.

Here:

Google Scholar

scholar.google.com

 

[Matt L]

My understanding is that our reef tanks are not like the ocean. In the ocean there is an ample supply of plankton to feed coral in the absence of nitrate, and nitrogen is exchanged continuously. In an aquarium, zooxanthellae require a higher nitrogen source to feed the coral, (they aren’t the same as in the ocean). This is species dependent and a blanket statement about nutrients doesn’t cover all aquariums. That’s most likely why some tanks bottom out in nitrate and others continuously climb.

I like to think of zooxanthellae as plants in a garden. Too little fertilizer and the plants stagnate and grow pale, too much and they burn out. Also, proper flow allows the exchange of gases that keep zooxanthellae and coral healthy. Flow is often the most overlooked parameter because we usually don’t quantify it in our thanks, but it can directly affect how nitrogen is utilized.

 

[sixty_reefer]

Hi

I think that while there are some forms of bacteria, dinoflagellates, protists etc that rely heavily on ammonia/ammonium and nitrates, most of the pest “algae” we see in our systems do indeed rely on pockets of accumulated waste. Definitely cyano and dinos at the very least.

Most likely though, since our systems are not the ocean, as much as we would like them to be, we should keep a small amount of nitrates until we know for sure that not having them at all would work in our systems long term.

I wouldn’t argue that nitrate isn’t important. Where I think it becomes more complicated is deciding what residual nitrate level is actually necessary.

To me, that falls into the category of “it depends.”

I think it depends on the aquarium, its stage of development and perhaps most importantly the aquarist’s experience. For a less experienced aquarist, maintaining a measurable nitrate level may provide a useful margin of safety and make it easier to recognise when nitrate availability could become limiting.

This is my thinking also. Plus, while air gets trapped in the mats, there is some circulation of water, hence waste, that circulates under the sand bed. It also falls on top of the mats too. Fish poop, uneaten food, blowing debris off the rocks etc.

I partially agree, but we can’t be sure that the water movement beneath the mat matches the flow above the mat, my opinion is that the flow will be restricted in some way, if we were to apply logic, a structure capable of trapping oxygen bubbles would likely alter water movement to some degree and may also affect nutrient exchange beneath it.

I see the mat a bit like a towel over our head when inhaling steam for a cold, the towel doesn’t create the steam, it simply helps retain it around the face and prevents it from dispersing as quickly into the surrounding air.

If there is some truth to that, then the low nitrate and phosphate levels observed by many aquarists could simply be a symptom of the dinoflagellate mat becoming established rather than the actual cause of the dinoflagellates.

 

[CHSUB]

My understanding is that our reef tanks are not like the ocean. In the ocean there is an ample supply of plankton to feed coral in the absence of nitrate, and nitrogen is exchanged continuously. In an aquarium, zooxanthellae require a higher nitrogen source to feed the coral, (they aren’t the same as in the ocean). This is species dependent and a blanket statement about nutrients doesn’t cover all aquariums. That’s most likely why some tanks bottom out in nitrate and others continuously climb.

I like to think of zooxanthellae as plants in a garden. Too little fertilizer and the plants stagnate and grow pale, too much and they burn out. Also, proper flow allows the exchange of gases that keep zooxanthellae and coral healthy. Flow is often the most overlooked parameter because we usually don’t quantify it in our thanks, but it can directly affect how nitrogen is utilized.

So that is an argument, “aquariums are not oceans and lack organic food” …that is a false statement imo as it is the hobbyist job to feed adequately. Which is why nitrates are only insurance for the novice. I have growing, thriving coral that is void of zooxanthella relying solely on capture of particulate food. While my aquarium doesn’t have the volume of food the ocean has, through my feeding, it has an adequate amount for even corals that lack zooxanthella.

 

[Lasse]

Do you do spot feeding on your sun coral? If so - do you have sun corals in spots there it is impossible to spot feed?



Sincerely Lasse

 

[Fishy888]

Hi



I wouldn’t argue that nitrate isn’t important. Where I think it becomes more complicated is deciding what residual nitrate level is actually necessary.

To me, that falls into the category of “it depends.”

I think it depends on the aquarium, its stage of development and perhaps most importantly the aquarist’s experience. For a less experienced aquarist, maintaining a measurable nitrate level may provide a useful margin of safety and make it easier to recognise when nitrate availability could become limiting.



I partially agree, but we can’t be sure that the water movement beneath the mat matches the flow above the mat, my opinion is that the flow will be restricted in some way, if we were to apply logic, a structure capable of trapping oxygen bubbles would likely alter water movement to some degree and may also affect nutrient exchange beneath it.

I see the mat a bit like a towel over our head when inhaling steam for a cold, the towel doesn’t create the steam, it simply helps retain it around the face and prevents it from dispersing as quickly into the surrounding air.

If there is some truth to that, then the low nitrate and phosphate levels observed by many aquarists could simply be a symptom of the dinoflagellate mat becoming established rather than the actual cause of the dinoflagellates.

I agree wholeheartedly with this. It’s likely that the combination of organisms in the mat are feeding on both the trapped organics and NO3/PO4 to some extent at the same time.

My thinking is that due to the drag/friction of the substrate, the flow over the mat in question would be stronger than under. Still, the flow is non-zero, so it’s possible for other organics to get piled up under the mat.

For a long time I was certain that low nutrients caused the conditions for dinoflagellates to take over due to the starvation of other competitors, such as algae of various types. While I still believe that dinos in particular won’t take over if there’s any real competition for resources, low nutrients aren’t the only means to limit the biodiversity needed to outcompete dinoflagellates.

Instead of only looking at NO3/PO4 when analyzing a dinoflagellate infestation, we should be looking at other potential factors that might be limiting competition. Because it’s still possible that nutrient limitation is occurring, that possibility shouldn’t be ignored.

 

[TokenReefer]

nstead of only looking at NO3/PO4 when analyzing a dinoflagellate infestation, we should be looking at other potential factors that might be limiting competition. Because it’s still possible that nutrient limitation is occurring, that possibility shouldn’t be ignored.

And because some can switch between heterotroph and autotroph the limiter may not affect them the same way. "Low nutrients" is just the bucket that the limiting one is in but it doesn't tell the full story.

 

[Fishy888]

And because some can switch between heterotroph and autotroph the limiter may not affect them the same way. "Low nutrients" is just the bucket that the limiting one is in but it doesn't tell the full story.

Very true!

 

[Randy Holmes-Farley Verified Community Expert]

The study above quotes the best research example of nitrate enrichment on coral calcification. It is definitive, absolutely, and without argument. Borneman and Sprung use this study specifically to explain nitrate effects on corals and aquariums in their books.

Here:

Google Scholar

scholar.google.com

I’m willing to accept that this study may be correct (despite a large number of all sorts of single biological studies being overturned later), but if skeletogenesis is the only concern, why is there not an equally strong criticism of having pH at 7.9 or alk at 7 dKH instead of pH 8.4 and alk of 10 dKH?

I would also note that they blame it on lack of available carbon, which perhaps is overcome at an alk of 9 dKH rather then the natural level in the 6’s.

 

[Matt L]

So that is an argument, “aquariums are not oceans and lack organic food” …that is a false statement imo as it is the hobbyist job to feed adequately. Which is why nitrates are only insurance for the novice. I have growing, thriving coral that is void of zooxanthella relying solely on capture of particulate food. While my aquarium doesn’t have the volume of food the ocean has, through my feeding, it has an adequate amount for even corals that lack zooxanthella.

Your tank likely doesn’t require elevated nitrate because you feed the coral. My point was about photosynthetic coral as well. This is not something that is done on all reef tanks, and many benefit from having nitrate in absence of food. Is nitrate “required”? No. But it is beneficial to many tanks depending on species and circumstances kept.
If you said “You don’t need nitrate if you feed your coral”, you are likely more correct.

 

[CHSUB]

I’m willing to accept that this study may be correct (despite a large number of all sorts of single biological studies being overturned later), but if skeletogenesis is the only concern, why is there not an equally strong criticism of having pH at 7.9 or alk at 7 dKH instead of pH 8.4 and alk of 10 dKH?

I would also note that they blame it on lack of available carbon, which perhaps is overcome at an alk of 9 dKH rather then the natural level in the 6’s.

I agree skeletogenesis is not the only concern in a reef aquarium and I’m at the point in my aquarium where slower growth might be beneficial? Also noted that carbon availability was ultimately the cause and not nitrates. Maybe provides more evidence that no3 is benign? Also if higher no3, one should increase Alk?

With a narrow focus on my original hypothesis and while I’m not a lawyer and this isn’t a court room; I did watch the OJ trial on TV…that is a joke BTW!

I’m told a good lawyer never asks a question that the answer isn’t known. If I was the lawyer in a court and asked to provide reasonable doubt to the following statement, “A health reef aquarium requires nitrates at a measurable level with a hobby test kit”, my first witness to the stand would be RHF. Who has a parameter range of 5 to 50 ppm nitrates for reef aquariums. I would thank Mr. Holmes-Farley for appearing and ask a single question with only a Yes or No for an answer; “Mr Holmes-Farley does a healthy reef aquarium required a measurable level of nitrates with a hobby test kit”? The answer would be “No” and I would call my next witness.

 

[Tripod1404]

The original argument you are making is that nitrate is not needed. The article I posted suggest some nitrate enrichment improves growth and resilience. You see focusing too much on their separate argument that there is a point in nitrate availability that this is reversed.

The argument for high nitrate reducing calcification is a separate argument. While I am sure that is true for wild corals in the ocean, as Randy point out, few people keep their tanks at natural sea water alk of ~6kH.

Overall coral growth is strongly influenced by the balance of nutrients, light and calcification building blocks. Corals tend to adapt well to “high alk and high nutrients” or “low alk and low nutrients”. An imbalance between these often causes issues, like low nutrients and high alk causes tip burning and high nutrients and low alk causes STN of the base. Like we knew for decades that ULN systems need alk and Ca within natural sea water levels to prevent tip burning and RTN, and that they are particularly sensitive to changes in light intensity and fluctuations in parameters.

All in all, it is probably related to whether corals can accelerate or decelerate their growth rate based on nutrient availability, which is strongly influenced by alk/Ca versus N/P balance. Light also plays a role in this, but is harder to draw conclusions. But I guess it is related to why tip burning happens at the site of a coral that gets the most light and STN happens at shaded parts (i.e., parts that grow very fast and parts that grow very slow).

Perhaps this may also explain why corals stressed to 29C grew faster when nitrate was enriched, compared to control corals at 26C with natural sea water. Similar to other variables above, temperature also has the potential to increase grow rate (enzyme rates increase with temperature), so high nitrate may allow corals to keep up with increased metabolic rates.

 

[Randy Holmes-Farley Verified Community Expert]

I would thank Mr. Holmes-Farley for appearing and ask a single question with only a Yes or No for an answer; “Mr Holmes-Farley does a healthy reef aquarium required a measurable level of nitrates with a hobby test kit”? The answer would be “No” and I would call my next witness.

Luckily, I would agree with myself. :)

 

[Randy Holmes-Farley Verified Community Expert]

The original argument you are making is that nitrate is not needed.

If that sentence is changed from

The original argument you are making is that nitrate is not needed.

t0

The original argument you are making is that nitrate is not always needed.

i think most of us would agree with it. :)

 

[CHSUB]

This kid is good, sure he is selling his products but the messages is solid. You don’t want zooxanthella happy, you want corals happy. Feed the corals, not the zooxanthella….

 

[Fishy888]

This kid is good, sure he is selling his products but the messages is solid. You don’t want zooxanthella happy, you want corals happy. Feed the corals, not the zooxanthella….

I saw that video in my feed last night. I haven’t watched it yet, but I agree, we want to keep the coral happy. Then again, keeping the coral happy means keeping the zooxanthellae happy enough to feed the coral.

 

[Lasse]

I’m willing to accept that this study may be correct (despite a large number of all sorts of single biological studies being overturned later), but if skeletogenesis is the only concern, why is there not an equally strong criticism of having pH at 7.9 or alk at 7 dKH instead of pH 8.4 and alk of 10 dKH?

I would also note that they blame it on lack of available carbon, which perhaps is overcome at an alk of 9 dKH rather then the natural level in the 6’s.

In a much later articles has the research group around Dr J. Wiedenmann produced articles that are interesting. In an article from 2022 - Impact of nitrogen (N) and phosphorus (P) enrichment and skewed N:P stoichiometry on the skeletal formation and microstructure of symbiotic reef coral they give a little bit different picture - at least for some stony corals. In earlier articles they have shown that too high N:P (molar to molar) ratio can cause bleaching if PO4 is below 0.02 mg/L but above this - it seems not be so critical. Worth to mention is what they state about acrophore spec -

The high number of studies reporting increased linear extension and/or calcification in Acropora spp. under HNHP conditions suggests that when the availability of both N and P is elevated, skeletal growth in this genus is enhanced. In contrast, whenever N:P ratios exceed ~72:1, the linear extension and calcification of Acropora spp. are more likely to be reduced, suggesting that the relative undersupply of P inhibits skeletal growth.

The study discussed earlier Nitrate increases zooxanthellae population density and reduces skeletogenesis in corals (Paywall but full article attached below ) discuss non Acropora species and may be right but I notice that the PO4 and NO3 concentration was only 0.05 (0,0048 mg/L) µM and 0.2 µM (0,0124 mg/L) -> ratio 4:1 in the control . The test NO3 was 1 (0,062 mg/L), 5 (0.31 mg/L) and 20 µM (1,24 mg/L) -> 8:1, 100:1 and 400:1. For me - is difficult to exclude PO4 starvation as a explanation. IMO - both these corals in this study is rather difficult corals to have in captivity - so it may be true.

Sincerely Lasse

And here is the article

 

[Randy Holmes-Farley Verified Community Expert]

In a much later articles has the research group around Dr J. Wiedenmann produced articles that are interesting. In an article from 2022 - Impact of nitrogen (N) and phosphorus (P) enrichment and skewed N:P stoichiometry on the skeletal formation and microstructure of symbiotic reef coral they give a little bit different picture - at least for some stony corals. In earlier articles they have shown that too high N:P (molar to molar) ratio can cause bleaching if PO4 is below 0.02 mg/L but above this - it seems not be so critical. Worth to mention is what they state about acrophore spec -



The study discussed earlier Nitrate increases zooxanthellae population density and reduces skeletogenesis in corals (Paywall but full article attached below ) discuss non Acropora species and may be right but I notice that the PO4 and NO3 concentration was only 0.05 (0,0048 mg/L) µM and 0.2 µM (0,0124 mg/L) -> ratio 4:1 in the control . The test NO3 was 1 (0,062 mg/L), 5 (0.31 mg/L) and 20 µM (1,24 mg/L) -> 8:1, 100:1 and 400:1. For me - is difficult to exclude PO4 starvation as a explanation. IMO - both these corals in this study is rather difficult corals to have in captivity - so it may be true.

Sincerely Lasse

Thanks, Lasse. :)

 

[Privateye]

I'm late to the party, and perhaps I missed something, but isn't this argument kind of moot?

The theory of the argument seems to check-out. Other forms of nitrogen can be utilized by the ornamental organisms we try to keep.

However, when we're dealing with closed systems that have active nitrification, can't we just assume that nitrate will be a part of its nitrogen cycling? We can add ammonia, but at least a portion of it will be converted to nitrate and nitrate tends to accumulate in such systems more than ammonia. Nitrate is also important for anaerobic denitrification. Nitrite can be utilized, but ammonia can't to my knowledge.

So maybe nitrate isn't always necessary, but to some degree it will always be present and take part in our tanks' life processes. It's a measurable player in this game. At least that's how I see it from my perspective.

 

[Randy Holmes-Farley Verified Community Expert]

I'm late to the party, and perhaps I missed something, but isn't this argument kind of moot?

The theory of the argument seems to check-out. Other forms of nitrogen can be utilized by the ornamental organisms we try to keep.

However, when we're dealing with closed systems that have active nitrification, can't we just assume that nitrate will be a part of its nitrogen cycling? We can add ammonia, but at least a portion of it will be converted to nitrate and nitrate tends to accumulate in such systems more than ammonia. Nitrate is also important for anaerobic denitrification. Nitrite can be utilized, but ammonia can't to my knowledge.

So maybe nitrate isn't always necessary, but to some degree it will always be present and take part in our tanks' life processes. It's a measurable player in this game. At least that's how I see it from my perspective.

I think the question relates more to the desirability of having detectable nitrate vs not having detectable nitrate. :)