NP Plus - Phosphate / Nitrate ratio

[ninjamyst]

According to previous threads on NP Plus, I am suppose to test phosphate only because nitrate is expected to remain 0 while using NP Plus. I did not know that at first so I kept dumping NP Plus and testing my nitrate. I finally got a Hanna Phosphate test kit and it is reading 0.39 for phosphate. My nitrate still tests 0. How do I know that my phosphate / nitrate are balanced? What phosphate / nitrate ratio will NP Plus produce? How can hobbyists even know if they can't test for nitrate while using NP Plus?

 

[Hans-Werner]

Just to clarify one thing: In biology there is no such a thing as a phosphate / nitrate ratio. While phosphate is the principal compound used for nearly all biological processes and compounds, nitrate is not. Nitrate is rather a waste product, the ashes of burnt excess nitrogen compounds.

When after mineralization there is still ammonium left, bacteria use its chemical energy to oxidize it to nitrate, which is a kind of final waste product of nitrogen cycle.

This means, most other available nitrogen compounds, organic compounds and ammonium, are of higher value for biological processes than nitrate. In fact nitrate may even be detrimental to corals if they really make use of it. By-products of nitrate assimilation are reactive oxygen species ROS which may damage and "burn" tissues. I am convinced that in most aquaria nitrate is of little use as a nutrient but only accumulates as a waste product while corals and algae mainly make use of ammonium and other reduced nitrogen compounds.

Plus-NP provides exactly these reduced nitrogen compounds which means it provides only little nitrate.

To answer your main question: The molare nitrogen : phosphate ratio of Plus-NP is 7 which would translate to a nitrate : phosphate ratio (if all nitrogen compounds would be oxidized to nitrate) of 7 x 62 : 95 or ca. 4.6 : 1.

This quite narrow N : P ratio pays tribute to the fact that most of the phosphate is incorporated into calcareous skeletons of corals and algae and not into biological tissues. This causes a narrow ratio of N : P consumption in calcareous organisms.

By the way, 85 % of phosphate of the human body is in the skeleton.

 

[ninjamyst]

Just to clarify one thing: In biology there is no such a thing as a phosphate / nitrate ratio. While phosphate is the principal compound used for nearly all biological processes and compounds, nitrate is not. Nitrate is rather a waste product, the ashes of burnt excess nitrogen compounds.

When after mineralization there is still ammonium left, bacteria use its chemical energy to oxidize it to nitrate, which is a kind of final waste product of nitrogen cycle.

This means, most other available nitrogen compounds, organic compounds and ammonium, are of higher value for biological processes than nitrate. In fact nitrate may even be detrimental to corals if they really make use of it. By-products of nitrate assimilation are reactive oxygen species ROS which may damage and "burn" tissues. I am convinced that in most aquaria nitrate is of little use as a nutrient but only accumulates as a waste product while corals and algae mainly make use of ammonium and other reduced nitrogen compounds.

Plus-NP provides exactly these reduced nitrogen compounds which means it provides only little nitrate.

To answer your main question: The molare nitrogen : phosphate ratio of Plus-NP is 7 which would translate to a nitrate : phosphate ratio (if all nitrogen compounds would be oxidized to nitrate) of 7 x 62 : 95 or ca. 4.6 : 1.

This quite narrow N : P ratio pays tribute to the fact that most of the phosphate is incorporated into calcareous skeletons of corals and algae and not into biological tissues. This causes a narrow ratio of N : P consumption in calcareous organisms.

By the way, 85 % of phosphate of the human body is in the skeleton.

Redfield ratio is 16N : 1P. If I can't test for nitrate, how do I know my nitrate is not bottomed out? Your post says that nitrate doesn't matter but I read that 0 nitrate is bad. That's why I am confused...

Are you saying that as long as I use NP Plus or Bacto Balance, your additives may ensure there's sufficient nitrate even if test kits cannot measure it?

 

[92Miata]

Redfield ratio is 16N : 1P. If I can't test for nitrate, how do I know my nitrate is not bottomed out? Your post says that nitrate doesn't matter but I read that 0 nitrate is bad. That's why I am confused...

Are you saying that as long as I use NP Plus or Bacto Balance, your additives may ensure there's sufficient nitrate even if test kits cannot measure it?

The Redfield Ratio has absolutely nothing to do with reefing. It is the ratio of C:N in deep water ocean plankton bulk biomass.

As Hans said, corals don't care about Nitrate. They need nitrogen, and would prefer pretty much every other form over nitrate. Keeping measurable nitrates is about having a backstop so that corals can spend energy to convert nitrate to ammonia and use that (It's biologically expensive, but better than death) as a failsafe.

The best way to make sure your fish are getting enough nitrogen is to add lots of ammonia dispensers - IE, fish.

 

[ninjamyst]

The Redfield Ratio has absolutely nothing to do with reefing. It is the ratio of C:N in deep water ocean plankton bulk biomass.

As Hans said, corals don't care about Nitrate. They need nitrogen, and would prefer pretty much every other form over nitrate. Keeping measurable nitrates is about having a backstop so that corals can spend energy to convert nitrate to ammonia and use that (It's biologically expensive, but better than death) as a failsafe.

The best way to make sure your fish are getting enough nitrogen is to add lots of ammonia dispensers - IE, fish.

Thank you! A lot of posts out there recommend getting nitrate above 0, preferably 5-10. That's why I am fixated on nitrate number. But it seems you are both saying nitrate doesn't really matter and phosphate and nitrogen are more important. And since we can't test for nitrogen, we have to just trust that if phosphate is above 0, there is enough nitrogen to support corals.

 

[GARRIGA]

The Redfield Ratio has absolutely nothing to do with reefing. It is the ratio of C:N in deep water ocean plankton bulk biomass.

As Hans said, corals don't care about Nitrate. They need nitrogen, and would prefer pretty much every other form over nitrate. Keeping measurable nitrates is about having a backstop so that corals can spend energy to convert nitrate to ammonia and use that (It's biologically expensive, but better than death) as a failsafe.

The best way to make sure your fish are getting enough nitrogen is to add lots of ammonia dispensers - IE, fish.

I bottom my nitrates and overfeed. Just fish only at present but no dinos or cyano and will continue this approach once ph fixed and corals added. My understanding of plants and algae being they have to convert nitrate down to ammonium and best just provide ammonium.

What I'm not fluent in being that final comment you made about adding more ammonia dispensers. Is that saying that direct ammonium input via feed is useless until converted by fish? Have assumed it's both.

 

[92Miata]

Thank you! A lot of posts out there recommend getting nitrate above 0, preferably 5-10. That's why I am fixated on nitrate number. But it seems you are both saying nitrate doesn't really matter and phosphate and nitrogen are more important. And since we can't test for nitrogen, we have to just trust that if phosphate is above 0, there is enough nitrogen to support corals.

I'm a fan of keeping nitrate above zero - primarily as the backstop I spoke about earlier. If you have 0 nitrate, it means all the ammonia and nitrite in your tank are being used - and that means corals are limited by those things, or close to it. It's not efficient for corals to use nitrate, but they can - and dosing ammonia scares people.

What I'm not fluent in being that final comment you made about adding more ammonia dispensers. Is that saying that direct ammonium input via feed is useless until converted by fish? Have assumed it's both.

No, I'm saying that fish are constantly releasing ammonia, and a slow steady drip of ammonia over the day is better than dumping a whole bunch of ammonia in at once via uneaten food (and spikes are a recipe for microalgae, which ramps up way faster than corals do)

 

[ninjamyst]

I'm a fan of keeping nitrate above zero - primarily as the backstop I spoke about earlier. If you have 0 nitrate, it means all the ammonia and nitrite in your tank are being used - and that means corals are limited by those things, or close to it. It's not efficient for corals to use nitrate, but they can - and dosing ammonia scares people.

But how can someone keep nitrate above zero if NP-Plus doesn't contain much nitrate? That's kind of the basis of my question. Do I need to dose nitrate separately from NP-Plus or just be ok with 0 nitrate (ie no backstop / failsafe) because NP-Plus is supplying enough nitrogen?

It sounds like the answer is "Don't worry about nitrate being 0". I am cool with that...saves me from testing it all the time =P.

 

[GARRIGA]

I'm a fan of keeping nitrate above zero - primarily as the backstop I spoke about earlier. If you have 0 nitrate, it means all the ammonia and nitrite in your tank are being used - and that means corals are limited by those things, or close to it. It's not efficient for corals to use nitrate, but they can - and dosing ammonia scares people.


No, I'm saying that fish are constantly releasing ammonia, and a slow steady drip of ammonia over the day is better than dumping a whole bunch of ammonia in at once via uneaten food (and spikes are a recipe for microalgae, which ramps up way faster than corals do)

Would nightly feedings solve the ammonium needs since it would be a direct path to the corals? Something I'm considering.

 

[Hans-Werner]

Redfield ratio is 16N : 1P. If I can't test for nitrate, how do I know my nitrate is not bottomed out? Your post says that nitrate doesn't matter but I read that 0 nitrate is bad. That's why I am confused...

The Redfield ratio is the ratio in the planktonic algae analyzed and it is not for calcifying organisms. It is not the concentrations in the water. The concentrations in the water also have to take into account the uptake mechanisms of i. e. corals and zooxanthellae.

Example: Corals need ca. 0.02 ppm phosphate and around the same concentration of nitrate to show net uptake of these nutrients. Below these concentrations there will be no uptake or even a net loss of these nutrients. If concentrations in the water are above these threshold levels they can take up these nutrients in any ratio as long as there is an unlimited supply. Now we have threshold levels of ca. 1 : 1. Where has the Redfield ratio gone now? Water has N : P concentrations of 1 : 1, coral tissue has maybe 16 : 1 and whole coral including skeleton has maybe 5 : 1 at the same time.

To make things even more confusing, I claim that corals need only little external nitrogen supply at all since symbiotic bacteria of corals are able to fix dissolved dinitrogen (N2) as ammonium and supply it to the coral.

Taking this together, low threshold levels for nitrogen uptake and use of N2 as N source, you don't need to care about N supply at all. The generally recommended nitrate concentration may be more about the oxidant nitrate than about the nutrient nitrate. Nitrate concentrations may be an efficient way to keep iron concentrations low in the water.

I know, this is all very, very complicated, but the interactions seem to be complex and not simple at all.

 

[Biologic]

Nitrate is rather a waste product, the ashes of burnt excess nitrogen compounds.

That's such a great way to put this topic into perspective.

Corals corals want N but not through NO3. The same type of thinking would be expecting to feed humans Carbon by giving them CO2. While perhaps the coral could use the NO3 in a pinch, you have the potential issues of ROS floating around.

 

[Biologic]

I've really been thinking about this low nitrate NO3- topic for months now. For years we've been approaching reefing like alchemy, but every year we are approaching this hobby more scientifically and socratically.

Still what puzzles me is the success of people elevating their nitrates beyond necessary from what literature and nature suggests. People are successfully keeping their tanks like this. It makes you wonder how? The close system variable has to be considered, but how can the animals and biology behave so differently in a closed environment? Excluding the obvious of plankton and alike. Especially when we know in situ (research based) preference of ammoniacal N and amino-based N are preferred.

I think where the hobby lacks is standardized set ups and chemistry testing, understandably. It also lacks repeatability. Then the marketing aspect, which I believe most companies todays have honest intentions, but still one has to be on guard. So it's so hard to discern what is truth.

I think the "rich" colors we see in the US are influenced by the amount of TON (total organic N) which could also lead to browning. This phenomena seems absent when I view German coral websites. They appear more pastel, but not necessarily "deprived" or unhealthy looking. Objectively both corals look healthy. And yes there are extreme examples of this. I love how the hobby differs so geographically, country to country. It's all very fascinating.

 

[Hans-Werner]

Still what puzzles me is the success of people elevating their nitrates beyond necessary from what literature and nature suggests. People are successfully keeping their tanks like this. It makes you wonder how? The close system variable has to be considered, but how can the animals and biology behave so differently in a closed environment?

My explanation and theory I have put together over the years is that there are different modes of nutrient supply corals can adapt to. It was and is necessary for corals to adapt to different conditions over space and time. Conditions may be different at different times and in different places.

So it is possible to keep corals with zooxanthellae limited by iron and nitrogen limitation and it is possible to keep them with iron and phosphate limitation. There is some difficulty for corals to change adaptation from one limitation to the other.

The more pastel colors should be typical for nitrogen limitation since chlorophylls are containing nitrogen. Zooxanthellae under nitrogen limitation reduce pigmentation which makes corals look lighter in color, more pastel colored.

Nitrate reduces availability of iron and phosphate. In a way the phosphate and iron limitation may be easier to achieve, especially under a high nutrient regime with lots of fish.

Important seems to me that there is some kind of limitation for the proper functioning of the zooxanthellae in the coral holobiont.

 

[Biologic]

So it is possible to keep corals with zooxanthellae limited by iron and nitrogen limitation and it is possible to keep them with iron and phosphate limitation.

I am trying to develop truths from what I observe and what you are explaining --

In almost all cases, in situ, in our homes, most corals are limited by iron, among other things, but taking Fe as the example. Most situations, people are not directly adding in iron daily unless Balling or doing some type of direct addition. The water changes uses up iron quickly and becomes limited again.

In many cases, they also be limited by nitrogen. Any forms of Nitrogen? Or specifically ammoniacal nitrogen? Or other higher organo-complex forms?

In almost many cases, but now tending to find its EASIER to be limited in phosphate. I use to love using RowaPhos, when the goal was driving down PO4 to zero was popular in the early 2000's. The bacteria seem to do a fine job on their own.

What is the most important rate limiter in this chemical equation? Is it P or is it Fe?

Is if different for color verses growth?

The more pastel colors should be typical for nitrogen limitation since chlorophylls are containing nitrogen. Zooxanthellae under nitrogen limitation reduce pigmentation which makes corals look lighter in color, more pastel colored.

I think I read you mentioning Nitrogen as a browning factor. Which makes sense, because of the density of zooxanthella. in my thoughts when there is high N, Fe, and P = an over abundance of zooxanthella.

FaunaMarin's theory of an Iodine-Phosphate relationship as a "browning factor" makes me curious as well. They observe too much iodine with too low of phosphate equals brown corals. In most cases, iodine is approaching limited in aquaria, right?

Nitrate reduces availability of iron and phosphate. In a way the phosphate and iron limitation may be easier to achieve, especially under a high nutrient regime with lots of fish.

Should the goal have always been chasing very low NO3- and actually measuring for higher forms of Nitrogen to ensure we have the forms that corals actually thrive in? Then adjust for the higher forms of N through supplements like aminos and ammoniacal nitrogen?


Why I am thinking about this so hard --

I am preparing to understand my tank in particular before I start using Tropic Marin Amino Organic and making observations on my Nitrate levels while using it, to know I am not dosing in excess but the right amount based on what I observe the corals do.

I am not sold on anything methodology at this point for Nitrate. I absolutely agree that phosphates in an aquarium have to be measurable and above 0.04 ppm from my Hanna URL "Phosphorus" reader, and if they are not, dinoflagellates rear their ugly head.

My observations with doing basic 10% water changes, weekly, using just kalkwasser, and with a very small fish population, is that Nitrogen has been limited. My nitrates have been very low. My phosphates remain fairly stable and low. Corals appear fine and healthy, but I personally would like to see what lighter tissue would look like.

 

[Hans-Werner]

In almost all cases, in situ, in our homes, most corals are limited by iron, among other things, but taking Fe as the example. Most situations, people are not directly adding in iron daily unless Balling or doing some type of direct addition. The water changes uses up iron quickly and becomes limited again.

I think it are coralline algae and hard corals themselves that induce iron limitation by incorporating relatively high proportions of iron into their skeletons. In this way they ecologically outcompete other algae.

In many cases, they also be limited by nitrogen. Any forms of Nitrogen? Or specifically ammoniacal nitrogen? Or other higher organo-complex forms?

Since all forms of nitrogen, also nitrate in a certain proportion, can be used by corals, all forms together may get limiting.

If sufficient light is available and light is not limiting, it will always be a nutrient that is growth limiting. Corals and/or algae will grow until one nutrient gets limiting. The challenge is to support coral growth without supporting nuisance algal growth too much. In my eyes this is much easier with nitrogen limitation than with phosphate limitation since corals can outcompete nuisance algae in competition for nitrogen but not (or much harder) in competition for phosphate.

What is the most important rate limiter in this chemical equation? Is it P or is it Fe?

Is if different for color verses growth?

If phosphate is limiting it will limit calcification and growth. Also corals may get more susceptible to damage from ROS/nitrate. Scientific articles on this subject are available and you should find them easily if you look for my other postings on this subject.

I think I read you mentioning Nitrogen as a browning factor. Which makes sense, because of the density of zooxanthella. in my thoughts when there is high N, Fe, and P = an over abundance of zooxanthella.

Phosphate has little influence on browning since phosphate is not limiting zooxanthellal pigmentation. Higher plants even get a darker blue-green color when phosphate is limiting because this causes a relative surplus of nitrogen. It is one of the symptoms of phosphate limitation in higher plants. Ecologically it may be similar in corals.

FaunaMarin's theory of an Iodine-Phosphate relationship as a "browning factor" makes me curious as well. They observe too much iodine with too low of phosphate equals brown corals. In most cases, iodine is approaching limited in aquaria, right?

Iodine might be the antagonist to nitrate regarding iron reduction and mobilisation. Iodate is reduced to iodide in surface waters. Iodide reacts with iron(III) to form iron(II) and iodine. Nitrate is oxidizing iron(II) to iron(III) or prevents the reduction of iron(III).

On the other side, if iron is not limiting, nitrogen may limit pigmentation or algal growth. This is especially important in the growth of nuisance algae and cyanobacteria, since these may have access to iron precipitates to which corals may have no access.

Should the goal have always been chasing very low NO3- and actually measuring for higher forms of Nitrogen to ensure we have the forms that corals actually thrive in?

No, nitrate may be the "tool" or "key" to iron limitation if you chose this way of running a tank.

 

[Biologic]

I think it are coralline algae and hard corals themselves that induce iron limitation by incorporating relatively high proportions of iron into their skeletons. In this way they ecologically outcompete other algae.


Since all forms of nitrogen, also nitrate in a certain proportion, can be used by corals, all forms together may get limiting.

If sufficient light is available and light is not limiting, it will always be a nutrient that is growth limiting. Corals and/or algae will grow until one nutrient gets limiting. The challenge is to support coral growth without supporting nuisance algal growth too much. In my eyes this is much easier with nitrogen limitation than with phosphate limitation since corals can outcompete nuisance algae in competition for nitrogen but not (or much harder) in competition for phosphate.


If phosphate is limiting it will limit calcification and growth. Also corals may get more susceptible to damage from ROS/nitrate. Scientific articles on this subject are available and you should find them easily if you look for my other postings on this subject.


Phosphate has little influence on browning since phosphate is not limiting zooxanthellal pigmentation. Higher plants even get a darker blue-green color when phosphate is limiting because this causes a relative surplus of nitrogen. It is one of the symptoms of phosphate limitation in higher plants. Ecologically it may be similar in corals.


Iodine might be the antagonist to nitrate regarding iron reduction and mobilisation. Iodate is reduced to iodide in surface waters. Iodide reacts with iron(III) to form iron(II) and iodine. Nitrate is oxidizing iron(II) to iron(III) or prevents the reduction of iron(III).

On the other side, if iron is not limiting, nitrogen may limit pigmentation or algal growth. This is especially important in the growth of nuisance algae and cyanobacteria, since these may have access to iron precipitates to which corals may have no access.


No, nitrate may be the "tool" or "key" to iron limitation if you chose this way of running a tank.

All of this makes perfect sense now. This really emphasizes Lou's talks on corals are great nitrogen scavengers, but poor phosphate consumers. Makes a lot more sense and gives more importance for that relationship.

The trace elements are very nuanced complex relationships and are difficult to observe accurately. Especially what oxidation state Fe is in ++ or +++. I assume most test kits choose one oxidation state to measure, or is it total?

Fe not being limited by NO3, with appropriate iodide levels, with measurable PO4-, ideally at 0.1 ppm, in my opinion based on what you are saying seems to be more ideal.

What an amazing journey this hobby has accomplished. Now we can discuss "ways to choose to run our tanks".