So do we want nutrients or not?

[Nano sapiens]

dkeller_nc - excellent.

Since photosynthetic corals, in particular, have multiple modes of acquiring nutrition I tend to look at the total nutritional content available to the them. While we can mimic the lighting on the reef (so as to provide the photosynthetic products that corals utilize) there is no way to duplicate the quantity and variety of food organisms available for capture in the wild. As a result we compensate by having higher dissolved nutrients along with higher bacteria densities.

The ability of corals to utilize a multitude of nutritional sources allows us to meet their energy needs for metabolism, pigmentation, aggression/defense, growth and reproduction within the captive environment. Truly remarkable animals they are!

 

[Rwpdunne]

While Randy's numbers are accurate, for a reef tank it may be missing the point. It would be nice to totally replicate a natural environment, but if you've ever been both day and night diving on a tropical reef, you know that this is not possible.

Specifically, while the actual water on a tropical reef may be very low in mineralized nutrients, there is a huge amount of plankton in the water every night, to the point where it can sometimes be difficult to see your dive buddies except for their lights.

This plankton is in all kinds of sizes, and all sorts of animals and plants, from single-celled organisms to 1/8" medusa, isopods, crustaceans and fish larvae. And it is typically present during most of the dark hours.

It's an often-repeated misconception that coral's preferred food is bacteria. This assertion isn't well supported by scientific publications, and also doesn't make sense when one considers the anatomy of most corals that we keep. The all have polyps, with visible tentacles. Nature doesn't waste energy on making anatomy that isn't well suited to the task at hand, and these tentacles are documented to be extremely efficient at capturing multi-celled, eukaryotic organisms. Bacteria, not so much.

That doesn't mean that coral won't ingest single-celled organisms, but their anatomy isn't ideal for the purpose. Sponges, tunicates, and mollusks on the other hand, are perfectly designed for this task.

However, in reef tank husbandry we can't fill the water during all of the dark hours with a large variety of plankton. Ergo, exactly duplicating the nutrient desert around a coral reef but also leaving out much of the nutrition available to corals in the wild doesn't make much sense.

And antectdotal evidence supports this idea - you can push mineralized nutrient levels to nearly zero, not feed the corals with some sort of zooplankton and/or phytoplankton substitute, and have the coral suffer bleaching, pale colors and STN.

Have a read of this

http://www.advancedaquarist.com/blog/bacteria-provide-corals-with-much-needed-nitrogen

Robbie

 

[dkeller_nc]

Yep, makes sense. There have been several scientific papers about bacteria and coral tissue association in the last couple of years.

However, this is definitely not the same as saying that bacteria are coral's preferred food, or even that they derive a large portion of their energy balance (nutrition) from them. What is clear is that photosynthetic corals are capable of capturing energy/nutrition from a variety of sources, from photosynthetic symbiosis with their zooxanthellae, to direct adsorption of nitrate/phosphorus from the water, to ingestion other organisms from pico-plankton to large fishes.

 

[Allmost]

And antectdotal evidence supports this idea - you can push mineralized nutrient levels to nearly zero, not feed the corals with some sort of zooplankton and/or phytoplankton substitute, and have the coral suffer bleaching, pale colors and STN.

I agree with your good points. Except last one ^.

we are taking all levels near zero, but there is food available for corals, all day and night long, in terms of free floating bacteria. It would perhaps be better if we could grow enough zooplanktons in tank, but thats not possible so ... this would explain tanks with near zero N and P, and corals flourishing and coloring up, and being healthy. there has to be an explanation for those right ?


I should not have called it preferred food though, you are right. ... what i meant was preferred food in an aquarium/ captive system.... until we can convert all the N and P into copepods biomass ?

 

[Rwpdunne]

Yep, makes sense. There have been several scientific papers about bacteria and coral tissue association in the last couple of years.

However, this is definitely not the same as saying that bacteria are coral's preferred food, or even that they derive a large portion of their energy balance (nutrition) from them. What is clear is that photosynthetic corals are capable of capturing energy/nutrition from a variety of sources, from photosynthetic symbiosis with their zooxanthellae, to direct adsorption of nitrate/phosphorus from the water, to ingestion other organisms from pico-plankton to large fishes.

I know its not saying bacteria is the preferred some of my sps catch some flake food I feed my fish and they consume it no problem

 

[dkeller_nc]

Well, here's another way to look at it. There have been recent scientific studies published on the human body that notes that there are considerably more living bacterial cells in the human body than there are of actual human cells.

Most of these are the gut flora/fauna, and their presence is required to the point where substantially disturbing the biotope with aggressive antibiotics can cause extremely serious health complications.

These bacteria are replenished on a regular basis from the food that we consume - we eat many billions of bacterial cells everyday. However, even though they are required for our continued health, and we eat them every day, they aren't considered "food" because we would perish within a month or so of discontinuing feeding on macro quantities of carbohydrates, protein and fats.

And while it might seem inane to compare human physiology to an animal that is as distantly related to us as scleractinians, it's not as dumb as it sounds. All life on earth has developed a physiology from common ancestors, to the point where the metabolic systems of most multi-cellular eukaryotes function very similarly.

What I conclude is that from a logical perspective at least, is that while assimilation of bacteria by stony corals has been proven in some species, and therefore probably is important to all (at least photosynthetes), that doesn't mean that they can reasonably be seen as a primary food source.

On this last count, I will note that I cannot say from personal experience, nor am I aware of any studies that have been carried out that say one way or another, but my impressions from reading those that use ULNS find that corals will become pale and will even potentially bleach without substantial feeding of the tank by fish food, an established copepod population, coral-specific food, allowing mineralized nutrients to rise, or all 4.

 

[hypnoj]

So the main question goes back to a thread I started several days ago on this forum... What are the coral-specific SPS foods commercially made (if any)? Also, does this mean all SPS dominant tanks would be wise to carbon dose to increase bacterial loads as a food source?

 

[88rxna]

A forum member (dowtish) is running ecobak pellets and having great luck with them!
http://www.reefcentral.com/forums/showthread.php?t=2304863

Is this something worth doing?

 

[franklypre]

Carbon dosing can be helpful and in my opinion is a good idea, that said over using carbon can be negative like over using most things in this hobby. Balance and stability along with a regular schedule/routine will out perform any single piece of equipment or method. I've never used biopellets, probably never will.

 

[Peter Eichler]

So the main question goes back to a thread I started several days ago on this forum... What are the coral-specific SPS foods commercially made (if any)? Also, does this mean all SPS dominant tanks would be wise to carbon dose to increase bacterial loads as a food source?

There really aren't any that I'm aware of... However, the 5-50 micron golden pearls are the proper size and have been successfully used in feeding various types of fish fry. So, they're nutritious, the correct size, and preetty inexpensive. However, there has been some debate over how the wheat and yeast in this product will be digested by corals. So, do some research before using. Other than that rotifers are your best bet.

 

[Allmost]

On this last count, I will note that I cannot say from personal experience, nor am I aware of any studies that have been carried out that say one way or another, but my impressions from reading those that use ULNS find that corals will become pale and will even potentially bleach without substantial feeding of the tank by fish food, an established copepod population, coral-specific food, allowing mineralized nutrients to rise, or all 4.

the corals get their energy fix from the bacteria they consume.

I will PM you some links.

 

[dkeller_nc]

Yes, I've read similar threads stating that bacteria are a primary food source for photosynthetic corals, but I just don't accept the argument, at least in its entireity.

Here is just one aspect that is debateable - the surface area in a L.R. reef tank, particularly one with an aragonite sand bed is massive, and would vastly exceed the surface area in the zeolite in a zeovit reactor.

Because mature bacterial biofilms shed constantly in liquid systems, it's highly questionable to imply that a zeo aquarium would be substantially different than any other live rock aquariums in terms of the bacterial content of the water.

That doesn't mean that I don't think a zeolite reactor has benefits for a reef aquarium, I just regard it as a nutrient absorber, particularly for phosphate. And needing to agitate the zeolite once a day makes perfect sense - formation of biofilms on molecular sieves and the resultant dimunition in their ability to absorb the intended molecules from aqueous solutions has been widely studied, so it would be necessary to "clean" this biofilm off of the zeolite on a regular basis.

But I don't think that this "bacterial mulm" as it has been termed substantially feeds corals, particularly SPS. Part of this is the history of the full-blown reef aquarium from the late 1980's through the 1990's. Essentially, these reef aquariums were the same as what is being used now - filtration primarily accomplished by skimming and the use of Live Rock. Nevertheless, certain species of SPS did not do well in these aquaria (though some did), and they would have had just as much bacteria in the water as a modern reef aquarium, and perhaps more because the capabilities of the typical skimmer has improved radically since then.

However, what is a big difference between now and then was the wide availability of food specifically intended for coral and designed to mimic zooplankton/phytoplankton. There are still occasional failures, of course, but modern reef systems with the addition of these foods can make keeping most an SPS alive and thriving.

 

[Allmost]

Yes, I've read similar threads stating that bacteria are a primary food source for photosynthetic corals, but I just don't accept the argument, at least in its entireity.

well thats science ... and it never stated that bacteria is the primary food source [in nature]. I had to read those articles twice, hope you found them and if you need to read the full article, let me know to send it to you. when the science is pointing to something, and research and observations support it, its hard to deny it after based on what one thinks


this is not about ZEOVIT, or has nothing to do with ZEOVIT, so lets keep ZEOVIT out of it. this is not about a method over another, this is about the theory in general terms, so I wont read your comment about the zeovit system. but I will add this article for you, which shows the bacteria count in our systems is much less than oceans.
Here. one tenth to be exact.

 

[hypnoj]

If indeed bacteria is a main food source for SPS corals, this would mean that you may be able to run a fishless SPS tank with nothing more then good lights and a carbon source (like vodka) to have them grow well. I wonder if this is being accomplished by anyone.

 

[sirreal63]

But I don't think that this "bacterial mulm" as it has been termed substantially feeds corals, particularly SPS. Part of this is the history of the full-blown reef aquarium from the late 1980's through the 1990's. Essentially, these reef aquariums were the same as what is being used now - filtration primarily accomplished by skimming and the use of Live Rock. Nevertheless, certain species of SPS did not do well in these aquaria (though some did), and they would have had just as much bacteria in the water as a modern reef aquarium, and perhaps more because the capabilities of the typical skimmer has improved radically since then.

I don't choose to disagree, however, I would like to point out that the bacterial growth in those legacy tanks were carbon limited, as is most tanks where a carbon source is not added. The addition of a carbon source will increase the bacterial population and if SPS are able to feed from the increased bacterial population then it does make sense that more food is available with a carbon dosed tank. This can be problematic when too much carbon is added and no3 and po4 are now limited as the corals still need no3 and po4 and bacteria may be able to out compete the corals for those nutrients.

 

[sanchoy]

I have kept zero n&p tanks in the past.

Now my sps tank has look better with high n&p. at zero n&p my tank suffered and bleached. I now feed heavy, dose vodka, and do semimonthly water changes. I rarely do phos test, my phos readings show up when their is hair algae in the tank.

 

[dkeller_nc]

I would like to point out that the bacterial growth in those legacy tanks were carbon limited, as is most tanks where a carbon source is not added. The addition of a carbon source will increase the bacterial population and if SPS are able to feed from the increased bacterial population then it does make sense that more food is available with a carbon dosed tank.

Indeed, although unfortunately it's not that simple a comparison. I can personally attest that modern skimmers are about an order of magnitude more effective than the ones in common use in the late 80's and 90's. Whether skimmers remove bacteria or not is not in doubt, since direct observation of the bacterial content of the skimmed material is pretty easy (and reproducible).

 

[dkeller_nc]

well thats science ... and it never stated that bacteria is the primary food source [in nature]. I had to read those articles twice, hope you found them and if you need to read the full article, let me know to send it to you. when the science is pointing to something, and research and observations support it, its hard to deny it after based on what one thinks

Yes, but the problem is that the science just isn't there. There are certainly some peer-reviewed articles that prove association with bacteria and even nitrogen transfer (latest Advanced Aquarist), but this is not the same as quantifying the nutritional energy balances that a typical SPS requires, and from what sources.

Early attempts to do this concluded (incorrectly) that photosynthesis was sufficient to provide more than 100% of a coral's total energy balances necessary to sustain growth and reproduction. There were some serious flaws in those studies that led to incorrect calculations.

But - what is needed is a quantification in a controlled experiment that uses isotopic trace analysis to quantify the various uptake rates/proportions of a coral in an environment that contains the variety of food sources that would be available to the coral (all the way from single-celled flora and fauna to macro flora and fauna).

So, unfortunately this is not a true statement:

"when the science is pointing to something, and research and observations support it"

At least from the standpoint of asserting that bacteria is a preferred food, or a necessary food, or even a food supplying substantial nutritional benefit. This is, by the way, a common misconception outside of the scientific community (or even within it, depending on what subject one is referring to) - that research that alludes to a specific hypothesis, or even a limited number of studies that support a specific hypothesis, constitutes a firm conclusion.

this is not about ZEOVIT, or has nothing to do with ZEOVIT, so lets keep ZEOVIT out of it. this is not about a method over another, this is about the theory in general terms, so I wont read your comment about the zeovit system. but I will add this article for you, which shows the bacteria count in our systems is much less than oceans.
Here. one tenth to be exact.

Actually, and so far as I'm aware, the progeniters of the Zeovit system were the first to formulate the hypothesis of bacteria a substantial source of coral nutrition, or at least the first to widely publicize/promote it. And the link you sent me was to the Zeovit forum, so you'll understand my confusion as to why the mention of the Zeovit system and the fundamental manner in which it is assumed to support coral health and growth is irrelevant to this thread.

 

[sirreal63]

Indeed, although unfortunately it's not that simple a comparison. I can personally attest that modern skimmers are about an order of magnitude more effective than the ones in common use in the late 80's and 90's. Whether skimmers remove bacteria or not is not in doubt, since direct observation of the bacterial content of the skimmed material is pretty easy (and reproducible).

Actually it is that simple, if a tank is carbon limited, then the quantity of bacteria will be lower than a tank that has carbon additions. If SPS are able to ingest bacteria (which I don't recall ever seeing proven, though it would not surprise me) then it follows that a tank with more bacteria will be able to provide more food in bacterial form than a tank that has less bacteria.

Modern skimmers have been shown to only remove up to about 39% of bacteria, reference the AA link that Allmost linked. :beer:

 

[dkeller_nc]

Actually it is that simple, if a tank is carbon limited, then the quantity of bacteria will be lower than a tank that has carbon additions. If SPS are able to ingest bacteria (which I don't recall ever seeing proven, though it would not surprise me) then it follows that a tank with more bacteria will be able to provide more food in bacterial form than a tank that has less bacteria.

Umm - not from a material balances point of view. It would most definitely be true that a tank that is carbon supplemented tank will produce more bacteria than a carbon limited one. However, if the skimmer on the carbon limited tank were considerably less effective than the one on a carbon supplemented tank, it doesn't follow that the carbon supplemented tank will necessarily have a greater concentration of bacteria per unit volume of water.