Nutrients vs Nutrition

[Randy Holmes-Farley Verified Community Expert]

Randy, thanks for chiming in! Here is how I am thinking about the difference between nutrients and nutrition. One example might be a tank with high nitrate and phosphate because waste and detritus have built up over time, but there is not much high-quality food available for the animals. In that case, the nutrient numbers are high, but the fish and corals may still not be getting everything they need to grow and stay healthy. Thoughts?

I guess a semantic discussion needs more definition, such as nutrition for what, and what nutrients are.

While reefers may not consider trace elements to be nutrients, other people certainly do. Organics as well, for organisms that need them. Protein is a nutrient for people by most folks reckoning. :)

 

[sixty_reefer]

I think that was actually part of the point Santa Monica was making - nutrients vs nutrition. You're describing nutrition, not nutrients.

I may be using the term more broadly than most aquarists, when I think about nutrients, I’m usually thinking about the overall nutritional needs of the organism rather than just nitrate and phosphate.

 

[SantaMonica Verified Sponsor]

DOC are molecules not particles.
Particles can be in suspension they are not dissolved.

The studies I've read usually point to particles less than a certain size that they specify for that study. And they say these particles are dissolved (as opposed to say, precipitated).

Really? Only carbon?

Primarily yes. Carbon based. There's other stuff sometimes but the idea is to differentiate organic from inorganic.

Proteins, fats, carbohydrates, vitamins are all nutrients.

Not as described here; that's why the confusion. For mammal diets, yes.

 

[Peace River]

I guess a semantic discussion needs more definition, such as nutrition for what, and what nutrients are.

While reefers may not consider trace elements to be nutrients, other people certainly do. Organics as well, for organisms that need them. Protein is a nutrient for people by most folks reckoning. :)

That's a fair point and thanks for the input! I may have been mixing the hobby use of "nutrients" (mostly nitrate and phosphate) with the broader biological meaning of nutrients. The distinction I was trying to get at was between the nutrient levels we commonly measure and the overall nutritional needs of the organisms in the tank.

 

[sixty_reefer]

That's a fair point and thanks for the input! I may have been mixing the hobby use of "nutrients" (mostly nitrate and phosphate) with the broader biological meaning of nutrients. The distinction I was trying to get at was between the nutrient levels we commonly measure and the overall nutritional needs of the organisms in the tank.

That’s one of the reasons I find biology and chemistry so interesting in this hobby. I often think about aquarium problems as a game of identifying what is limiting growth for a particular organism.

If someone tells me they have high nitrate and phosphate, my first thought is not necessarily how to lower nitrate and phosphate. Instead, I start wondering what resource is preventing those nutrients from being utilized.

For example, if nitrate and phosphate are abundant, perhaps organic carbon is limiting bacterial growth. In that case, adding an organic carbon source may increase bacterial biomass and nutrient uptake. Alternatively, perhaps there is insufficient photosynthetic biomass to take advantage of the available nutrients. In that case, adding macroalgae or encouraging other photosynthetic organisms may shift the system in a different direction.

The funny thing is that this way of thinking originally came from my attempts to understand the Redfield ratio. For a while, the main practical value I took from it was the idea that one resource can limit the use of another. Later, after reading Randy’s article “Liebig the Man,” I realized I was really describing Liebig’s Law of the Minimum rather than Redfield itself.

Since then, I’ve found it useful to think of nitrate, phosphate, carbon, trace elements, light and even space as potentially limiting resources. Once you start looking at the aquarium through that lens, nutrient levels become less of an answer and more of a clue.

I may be a weird aquarist, but I find those thought experiments fascinating.

 

[sixty_reefer]

On a serious note, I think there is an opportunity here for someone like @Randy Holmes-Farley to take this concept further from a reef aquarium perspective.

While Liebig’s Law was originally developed for agriculture, the underlying principle translates remarkably well to reef aquariums. In many ways, it provides a bridge between chemistry and biology, two subjects that aquarists often discuss separately.

What I find compelling is that it shifts the focus away from simply measuring nitrate and phosphate and toward identifying what is actually limiting the organism in question. Whether that limiting factor is carbon, light, trace elements, flow, space or something else entirely, the thought process remains the same, what resource is preventing growth, competition or nutrient utilisation?

I think many of the apparent contradictions in reef keeping begin to make more sense when viewed through that lens. Nutrient levels stop being the answer and instead become clues that help us identify what may be limiting the system.

I genuinely believe that a modern reef aquarium interpretation of this concept could help thousands of aquarists troubleshoot problems more effectively. Randy has the scientific background, reef keeping experience and communication skills to turn what is often an abstract principle into a practical framework that everyday aquarists can apply to their own aquariums.

If that could be distilled into a simple concept that hobbyists readily understand, I think it could influence how aquarists think about nutrients, algae and nutrient control for years to come.

 

[BeanAnimal]

Let's talk nutrients
.The words "nutrient" and "nutrition" are commonly confused when talking about reefs...

I don't see any confusion, these words are typically used with contextually clear understanding of what they are being used to represent.

I think that was actually part of the point Santa Monica was making - nutrients vs nutrition. You're describing nutrition, not nutrients.

But I am struggling to sort out exactly to what end.

I’ve always found it a bit strange how often we use “nutrients” as shorthand for nitrate and phosphate.

To me, nutrients are anything an organism needs to stay alive. Nitrate and phosphate are part of that picture but they’re only a small part of it.

It also depends on the organism in question. What counts as an important nutrient for one organism may not be nearly as important for another and different organisms obtain what they need in different ways.

Why is it strange?

When we speak of "nutrients" we are contextually speaking of what we can broadly test for and attempt to directly control via import or export intervention. The word us used with specific context that serves its purpose.

---

Let's try this:
I've always found it a bit strange how often we use "food" as shorthand for fat, carbohydrates and protein.

To me, food is anything an organism needs to stay alive. Fat, carbohydrates and protein are part of that picture but they're only a small part of it.

It also depends on the organism in question. What counts as an important food for one organism may not be nearly as important for another and different organisms obtain what they need in different ways.

---

It is statement begging complexity of something that doesn't need to be complex. If one means to discuss the intricacies of what makes up food, then food is used in a different context and still clearly in place.

So, what is strange to me is these threads where we work overtime to wrap simple understood contexts and terminology into something begging to be more complex, simply for the sake of complexity. Often wraping a simple usefull point or understanding with vagary and abstraction that can't be measured or clearly defined. We end up with less clarity and a whole lot of fancy words to pretend that we understand or steer more than we do.

...and this is why we are having a discussion. The fact that someone opened the space for others to add informative information is a positive. Thanks for jumping in and sharing your thoughts!

Sure, but I would argue that some conversation makes things more complicated than need be. Here the words are used in different contexts for a reason, shorthand maybe, but well understood.

You guys think too much.

The word for the month is sophistry. "Presenting clever but ultimately empty arguments as if they are wisdom"

There is nothing wrong with a discussion, but tilting at windmills is still tilting at windmills.

 

[BeanAnimal]

On a serious note, I think there is an opportunity here for someone like @Randy Holmes-Farley to take this concept further from a reef aquarium perspective.

Randy already did. He wrote "Forget Redfield, Liebig is the Man." You are asking him to reframe his own work and Liebig itself to validate a framework neither was intended to support. In fact, the article explicitly warns against using it as a catch-all.

Randy's article is specific and bounded. Liebig identifies one limiting factor at a time for one organism at a time. The value is in identifying what that limiter is, measuring it, and changing it.

"nitrate, phosphate, carbon, trace elements, light and even space as potentially limiting resources" is stating the obvious that something is always limiting somewhere in some tank under some conditions. That covers every outcome in every system. It says nothing but sounds like insight. That is not an application of Liebig. It is Liebig's name used as science sounding decorative cover for a framework that does no work but states the obvious. Nominating Randy to expand on it borrows his credibility for the same purpose.

 

[sixty_reefer]

Randy already did. He wrote "Forget Redfield, Liebig is the Man." You are asking him to reframe his own work and Liebig itself to validate a framework neither was intended to support. In fact, the article explicitly warns against using it as a catch-all.

Randy's article is specific and bounded. Liebig identifies one limiting factor at a time for one organism at a time. The value is in identifying what that limiter is, measuring it, and changing it.

"nitrate, phosphate, carbon, trace elements, light and even space as potentially limiting resources" is stating the obvious that something is always limiting somewhere in some tank under some conditions. That covers every outcome in every system. It says nothing but sounds like insight. That is not an application of Liebig. It is Liebig's name used as science sounding decorative cover for a framework that does no work but states the obvious. Nominating Randy to expand on it borrows his credibility for the same purpose.

I don’t think I’m asking Randy to redefine Liebig’s Law or use it as a catch it all explanation for reef aquariums.

What I found valuable in his article was the shift in thinking from “What nitrate and phosphate level should I have?” to “What resource is limiting the organism I’m interested in?”

That doesn’t identify the limiting factor by itself, nor does it explain every outcome in every aquarium. It simply changes the question being asked.

For example, if nitrate and phosphate are accumulating, my next thought isn’t automatically that carbon is limiting, it’s that something is preventing those nutrients from being incorporated into biomass at the same rate they’re entering the system, determining what that “something” is becomes the interesting part.

That’s the practical value I took from Randy’s article, not as a universal theory of reef keeping but as a useful framework for asking better questions when troubleshooting aquarium problems.

 

[BeanAnimal]

I don’t think I’m asking Randy to redefine Liebig’s Law or use it as a catch it all explanation for reef aquariums.

What I found valuable in his article was the shift in thinking from “What nitrate and phosphate level should I have?” to “What resource is limiting the organism I’m interested in?”

That doesn’t identify the limiting factor by itself, nor does it explain every outcome in every aquarium. It simply changes the question being asked.

For example, if nitrate and phosphate are accumulating, my next thought isn’t automatically that carbon is limiting, it’s that something is preventing those nutrients from being incorporated into biomass at the same rate they’re entering the system, determining what that “something” is becomes the interesting part.

That’s the practical value I took from Randy’s article, not as a universal theory of reef keeping but as a useful framework for asking better questions when troubleshooting aquarium problems.

But you did directly nominate Randy to expand on it. It was not misunderstood.

Asking better questions is only useful if the answers are reachable. If they are not, it is not a troubleshooting framework or insight. It is just a more decorated way of saying we do not know. It does no work other than obfuscating what is simple under layers of abstraction to sound sophisticated.

I have pointed out the problem with the framework several times. Identifying the limiting factor requires measuring it. The underlying problem with your overarching framework, as built on and expanded over the course of dozens of threads, is that we cannot measure most of what is being discussed here or there.

A framework that absorbs every variable, carbon, light, space, organics, maturity, and adjusts to fit every outcome cannot be wrong. That is the definition of an unfalsifiable framework that serves no purpose, even when liberally hedged in "I think", " it depends", and "may be wrong" terminology.

It is not a useful framework for asking better questions. It is Liebig's and Randy's names borrowed to add weight to claims that cannot be tested and cannot be wrong.

 

[Dan_P]

I guess a semantic discussion needs more definition, such as nutrition for what, and what nutrients are.

Maybe, this could be another simplification example, using two technical terms interchangeably, resulting in little or no harm.

 

[Dan_P]

For example, if nitrate and phosphate are accumulating, my next thought isn’t automatically that carbon is limiting, it’s that something is preventing those nutrients from being incorporated into biomass at the same rate they’re entering the system, determining what that “something” is becomes the interesting part.

Why would you assume something is preventing nutrients from being consumed rather than the system is being provided nutrients it does not need? This seems like a case of overcomplicating things. Forget Liebig, think Occam.

 

[sixty_reefer]

Why would you assume something is preventing nutrients from being consumed rather than the system is being provided nutrients it does not need? This seems like a case of overcomplicating things. Forget Liebig, think Occam.

I tend to assume the aquarist is already adding the amount of food their fish require to remain healthy. Sometimes that assumption may be wrong but I’m not really interested in judging feeding practices.

If nitrate and phosphate begin to accumulate under those conditions, my interest is in understanding why the system is no longer processing those nutrients at the same rate they’re being introduced.

 

[TokenReefer]

I tend to assume the aquarist is already adding the amount of food their fish require to remain healthy. Sometimes that assumption may be wrong but I’m not really interested in judging feeding practices.

Wouldn't this require (precise) measurements of food; to make that assumption? What if the "pinch" was bigger today? I would find it hard to assume the input is exactly the same every day so that's a variable for me

 

[sixty_reefer]

Wouldn't this require (precise) measurements of food; to make that assumption? What if the "pinch" was bigger today? I would find it hard to assume the input is exactly the same every day so that's a variable for me

My answer would be “it depends” as I’ve discussed on a different thread.

 

[BeanAnimal]

My answer would be “it depends” as I’ve discussed on a different thread.

It depends is not an answer. It is a new shell game that guarantees the framework can never be wrong.

 

[sixty_reefer]

It depends is not an answer. It is a new shell game that guarantees the framework can never be wrong.

I think “it depends” was a reasonable answer because the question lacked sufficient context.

Without defining some of the variables, I don’t think a simple yes or no answer is possible, for example, the type of food being used, how consistently it is being fed, whether the food is being consumed or accumulating in the system and the timescale being discussed could all influence the answer.

In that context “it depends” wasn’t intended as a shell game, as you have insinuated. It was simply the most accurate answer I could give based on the information provided.

I believe @TokenReefer understood the intent of my reply.

 

[BeanAnimal]

One would have to ignore context to accept that there was not sufficient context. This thread itself and Dan's and Token's direct questions, and my response above clearly framed the context.

Both questions directly undermine the assumption your framework requires. Neither received a direct answer, nor did I earlier. So "It depends" is a catch-all that leaves the questions unanswered. Token understanding your intent is not the same as your framework surviving the question.

 

[sixty_reefer]

One would have to ignore context to accept that there was not sufficient context. This thread itself and Dan's and Token's direct questions, and my response above clearly framed the context.

Both questions directly undermine the assumption your framework requires. Neither received a direct answer, nor did I earlier. So "It depends" is a catch-all that leaves the questions unanswered. Token understanding your intent is not the same as your framework surviving the question.

“It depends”

 

[Randy Holmes-Farley Verified Community Expert]

I am certain that I am not adding exactly what my fish need. Likely substantially more, but I have no way to really know without endless and uninteresting experiments reducing food until fish are visibly declining.