Nutrition vs. Nutrients

[SantaMonica]

Here is some info on understanding Nutrition (food) compared to Nutrients (waste)...

The word "nutrient" and "nutrition" are commonly confused when talking about reefs. "Nutrition" is just like food; it feeds the fish and the corals and the microbes. Nutrition include fish waste, coral slime, leftover food particles, algae (yum sushi), vitamins, and amino acids. This nutrition can be in the form of pieces or particles that you can see, or very very small particles that you cannot see call dissolved organic carbon ("DOC") . All this nutrition feeds some animal or microbe somewhere in your system, and it is the carbon in this nutrition that is being sought.

"Nutrients" however are different; they are Nitrate, Nitrite, Inorganic (Ortho) Phosphate, Ammonia, and Ammonium, i.e., the things your test kits test for. There is no carbon in these; just nitrogen, phosphorus, oxygen and hydrogen. Nutrients are what remain after the food chain does it's work, all the way down to the last bacteria. This is also called "re-mineralization", because all the organic particles have had the carbon removed such that only the "minerals" (nitrogen etc) remain.

 

[Mr. Mojo Rising]

Thanks very much for writing that!

Is there a way to measure DOC's in our aquarium?

 

[SantaMonica]

Thanks.

You actually don't need to measure DOC (the O=organics) because that is just dissolved food particles (like glucose) that you feed the corals. So, just like a real reef, you want them to be as high as possible.

It's the inorganics that you want to measure and keep low as possible.

 

[ISpeakForTheSeas]

Thanks very much for writing that!

Is there a way to measure DOC's in our aquarium?

No, there's currently no method for measuring Dissolved Organic Matter (Carbon, Nitrogen, or Phosphorus) at home - maybe Randy, Dan, or Taricha would have an idea for how to try and DIY measure it, but having looked into the methods used to measure these a little bit since it's a major component of sponge diets, it basically requires a lab to measure at this point.

 

[Randy Holmes-Farley]

I don't know what use it would be to measure DOC (dissolved organic carbon) since it contains a huge variety of things, some of which are desirable and some are not, except knowing when to replace GAC.

 

[Randy Holmes-Farley]

You actually don't need to measure DOC (the O=organics) because that is just dissolved food particles (like glucose) that you feed the corals. So, just like a real reef, you want them to be as high as possible.

It's the inorganics that you want to measure and keep low as possible.

I do not agree that keeping these "as low as possible" is desirable since they can certainly be too low for the organisms we keep to thrive.

I also do not agree that one wants DOC as high as possible. That leads to yellow water and can include accumulating toxins and encourage cyanobacteria.

 

[GARRIGA]

My simplistic approach. Ammonium is nutrition for plants. Is it not? Everything has a consumer. In simplistic terms.

 

[Garf]

So, just like a real reef, you want them to be as high as possible.

Are you not describing the benefit of Particulate instead of Dissolved, and implying they are the same?. Water described as full of the Dissolved variant cunjurs up the word Eutrophic in my mind, although indeed that is a result of algae proliferation.

 

[SantaMonica]

My simplistic approach. Ammonium is nutrition for plants. Is it not? Everything has a consumer. In simplistic terms.

Yes in freshwater especially, But it's taken up so quick by periphyton etc in reefs that it's always zero-ish.

Are you not describing the benefit of Particulate instead of Dissolved, and implying they are the same?. Water described as full of the Dissolved variant cunjurs up the word Eutrophic in my mind, although indeed that is a result of algae proliferation.

Both. Reef water is loaded with both, which is different of course than a eutrophic lake, which is also loaded with both. The idea is that clear water does not necessarily mean the water is good for corals. High organics, and low inorganics (i.e. real reef water) is good however. High organics does not require that the water be brown/tan, many reef organics are clear.

 

[Garf]

Yes in freshwater especially, But it's taken up so quick by periphyton etc in reefs that it's always zero-ish.


Both. Reef water is loaded with both, which is different of course than a eutrophic lake, which is also loaded with both. The idea is that clear water does not necessarily mean the water is good for corals. High organics, and low inorganics (i.e. real reef water) is good however. High organics does not require that the water be brown/tan, many reef organics are clear.

High levels of green algae derived dissolved organics certainly tends to favour algae associated micro stuff, like bacteria, well at least it used to.

 

[SantaMonica]

More:

A real reef, and the basic idea of a reef tank, is to maximize nutrition for good fish and coral growth, but minimize nutrients in order to reduce nuisance algae growth. Skimmers, which are "protein" skimmers, only remove nutrition, which is great if all you have is fish; but skimmers have no effect on nutrients because nitrate etc does not stick to the air bubbles. Matter of fact if you took a fresh batch of newly made saltwater and put a skimmer in it, and then added pure nutrients, the skimmer would not have any skimmate at all even though nitrate, phosphate etc were sky high. However if you added nutrition (phyto, plankton, ground up flakes, coral food, etc) to that same batch of saltwater, the skimmer would go crazy.

Algae, however, do consume nutrients, and would start growing out of control in this high nutrient saltwater. That's why a tank can have lots of algae, but low nutrients: because the nutrients are all consumed by the algae. You have to remove this algae from the tank however.

Another way to understand this is to think about cooking a steak in your kitchen. The steak (nutrition) is what you want, but the smoke (nutrients) is what you don't want. You want to keep the steak in your kitchen (keep the nutrition in your water), but you want to remove the nutrients; so you use an exhaust fan to remove the smoke, and you use algae to remove the nutrients.