How to successfully keep SPS Corals!

[pdiehm]

Zeo is very expensive.

tried it before i took my tank down, and while it wasn't the reason nothing lived, it was expensive buying those bottles every month.

 

[mcarroll]

For lack of a better reference it's like buying a frag on line at its best appearance, best lighting, etc but when you put it in the tank it's never has quite the same look as that picture.

That's the camera and lens used for the photo being superior to the human eyeball.....higher res capability, mainly I think.....corals in person never look as good as pics from a camera like that. Our eyeballs limit us from that possibility. (The marketing folks know that too. :rolleyes:)

I just feel it makes a noticeable difference in appearance, basically.

Interesting!

I found some pretty interesting articles on google scholar about trace elements, but nothing about corals using them (or not using them) for anything. Not too helpful.

 

[Elegance Coral]

Awesome tank! And don't change a thing – but corals do "eat" plenty of dissolved nutrients in the wild. Nothing bad or even abnormal about it. :)

(I bet you'd be surprised at how much your corals consume in your tank if that was something we could know.)

Thank you :)

https://www.sciencedirect.com/science/article/pii/S0966842X1500075X

Above is a link you may find interesting. Here's a quote from the link.
"Tropical reef-building corals commonly flourish in nutrient-poor environments. The contradiction of high coral productivity on the one hand and limited nutrient availability on the other hand has been coined the ‘Darwin Paradox’"
If these corals did "eat plenty of dissolved nutrients in the wild", we would not have the "Darwin Paradox". There isn't "plenty of dissolved nutrients in the wild" for them to "eat" even if they wanted to. Which they don't. They have evolved to thrive without plenty of dissolved nutrients. In fact, many coral reefs around the world are now in serious trouble because there is now plenty of dissolved nutrients in the water.

This belief, that corals are highly dependent, or receive plenty, of dissolved nutrients from the water has been fueled, in part, by an industry that makes millions selling magic liquid potions to "feed" our corals. More recently, this belief has received a boost in popularity with the ULNS, and the addition of things like stump remover and other inorganic sources of nitrogen and phosphorus, or even additives with "proprietary" ingredients. Unfortunately, most hobbyist don't quite understand what's taking place here. People starve their corals to achieve the ULNS status, then begin to see negative symptoms of that starvation. They then add fertilizers (inorganic nitrogen and phosphorus) and the corals improve. Problem solved, right??? No..... No it's not.

In the wild, on healthy growing coral reefs, these coral obtain the vast majority of their nitrogen and phosphorus from capturing and digesting tiny organic particles. Everything from microbes up to tiny zooplankton, or even fish poo. (One tiny copepod contains a concentration of nutrients that is many, many, many, many, many times greater than the water around it.) Their zooxanthellae then obtain their nitrogen and phosphorus from the waste produced by this feeding. In lean times, when food is scarce, the coral animal can temporarily meet its nutritional requirements by digesting its own zooxanthellae.
Another quote from the link above. "Control of algal numbers by degradation/digestion [35]. Via this process the host may benefit from the organic nutrients contained in the symbionts."

Science has also shown that when a coral captures food, it stops digestion of its own zooxanthellae. https://www.google.com/url?url=http...QgAMIKCgAMAA&usg=AOvVaw1BIA9DHcMg8BAVoYr71Y1N
A quote from this link.
"(4) the polyps regulate the intensity of algal degradation which is stimulated by a deflciency of food, and degradation is rapidly terminated upon reintroduction of food"
So in other words, when a coral is starving it will resort to digestion of its own zooxanthellae, but the moment it obtains food it stops feeding on its own zooxanthellae.

By starving a coral, then adding fertilizer to the system, people are forcing their coral to sustain itself on its own zooxanthellae. Not on real food as nature intended.

Through this process, the coral is able to utilize its zooxanthellae similar to the way we use fat cells. If we could take a starving person and artificially increase his or her fat cells, that person would likely improve through the degradation/digestion of these new fat cells. However, the person would still be starving. This is not a method to achieve optimum health, growth, and reproduction. It is simply a survival technique. .
When we add dissolved PO4 and/or NO3 to a starving SPS coral, we are artificially increasing its zooxanthellae population. The coral can improve, but it's just an improvement over total starvation and death. It's hardly a path to optimum health, growth, and reproduction. For that, the coral needs to feed. Just as they do in the wild. By feed, I mean the coral needs to capture and digest solid organic material. They have very very little, if any, direct dependence on dissolved nutrients in the water.

Peace
EC

 

[pdiehm]

Thank you :)

https://www.sciencedirect.com/science/article/pii/S0966842X1500075X

Above is a link you may find interesting. Here's a quote from the link.
"Tropical reef-building corals commonly flourish in nutrient-poor environments. The contradiction of high coral productivity on the one hand and limited nutrient availability on the other hand has been coined the ‘Darwin Paradox’"
If these corals did "eat plenty of dissolved nutrients in the wild", we would not have the "Darwin Paradox". There isn't "plenty of dissolved nutrients in the wild" for them to "eat" even if they wanted to. Which they don't. They have evolved to thrive without plenty of dissolved nutrients. In fact, many coral reefs around the world are now in serious trouble because there is now plenty of dissolved nutrients in the water.

This belief, that corals are highly dependent, or receive plenty, of dissolved nutrients from the water has been fueled, in part, by an industry that makes millions selling magic liquid potions to "feed" our corals. More recently, this belief has received a boost in popularity with the ULNS, and the addition of things like stump remover and other inorganic sources of nitrogen and phosphorus, or even additives with "proprietary" ingredients. Unfortunately, most hobbyist don't quite understand what's taking place here. People starve their corals to achieve the ULNS status, then begin to see negative symptoms of that starvation. They then add fertilizers (inorganic nitrogen and phosphorus) and the corals improve. Problem solved, right??? No..... No it's not.

In the wild, on healthy growing coral reefs, these coral obtain the vast majority of their nitrogen and phosphorus from capturing and digesting tiny organic particles. Everything from microbes up to tiny zooplankton, or even fish poo. (One tiny copepod contains a concentration of nutrients that is many, many, many, many, many times greater than the water around it.) Their zooxanthellae then obtain their nitrogen and phosphorus from the waste produced by this feeding. In lean times, when food is scarce, the coral animal can temporarily meet its nutritional requirements by digesting its own zooxanthellae.
Another quote from the link above. "Control of algal numbers by degradation/digestion [35]. Via this process the host may benefit from the organic nutrients contained in the symbionts."

Science has also shown that when a coral captures food, it stops digestion of its own zooxanthellae. https://www.google.com/url?url=http://scholar.google.com/scholar_url?url=http://www.int-res.com/articles/meps/139/m139p167.pdf&hl=en&sa=X&scisig=AAGBfm0kjzDcaNuAESmAcXJneit7K4f72A&nossl=1&oi=scholarr&rct=j&q=&esrc=s&sa=X&ved=0ahUKEwiHvaKZ57TZAhUJDKwKHSuDBP8QgAMIKCgAMAA&usg=AOvVaw1BIA9DHcMg8BAVoYr71Y1N
A quote from this link.
"(4) the polyps regulate the intensity of algal degradation which is stimulated by a deflciency of food, and degradation is rapidly terminated upon reintroduction of food"
So in other words, when a coral is starving it will resort to digestion of its own zooxanthellae, but the moment it obtains food it stops feeding on its own zooxanthellae.

By starving a coral, then adding fertilizer to the system, people are forcing their coral to sustain itself on its own zooxanthellae. Not on real food as nature intended.

Through this process, the coral is able to utilize its zooxanthellae similar to the way we use fat cells. If we could take a starving person and artificially increase his or her fat cells, that person would likely improve through the degradation/digestion of these new fat cells. However, the person would still be starving. This is not a method to achieve optimum health, growth, and reproduction. It is simply a survival technique. .
When we add dissolved PO4 and/or NO3 to a starving SPS coral, we are artificially increasing its zooxanthellae population. The coral can improve, but it's just an improvement over total starvation and death. It's hardly a path to optimum health, growth, and reproduction. For that, the coral needs to feed. Just as they do in the wild. By feed, I mean the coral needs to capture and digest solid organic material. They have very very little, if any, direct dependence on dissolved nutrients in the water.

Peace
EC

For those of us who are not biologically inclined...SPS corals do not have mouths like say an LPS. If they need food, how does an aquarist manage that? I know I dose Reef Energy A & B to the tank daily, and I probably over feed my fish.

How do I go about "feeding" my coral solid organic material or is that just something that happens with their polyps? I know my Stylophora about an hour after I feed the fish, it is often seen with it's polyps pulled in, and I just took that as, it went from flow, to no flow, back to flow, and it's ticked. Or am I actually not seeing displeasure but rather possible feeding?

 

[Elegance Coral]

For those of us who are not biologically inclined...SPS corals do not have mouths like say an LPS. If they need food, how does an aquarist manage that? I know I dose Reef Energy A & B to the tank daily, and I probably over feed my fish.

How do I go about "feeding" my coral solid organic material or is that just something that happens with their polyps? I know my Stylophora about an hour after I feed the fish, it is often seen with it's polyps pulled in, and I just took that as, it went from flow, to no flow, back to flow, and it's ******. Or am I actually not seeing displeasure but rather possible feeding?

Acropora do have mouths, just like LPS, just on a much smaller scale. It is totally possible that you're seeing a feeding response in your stylo.
IMHO Reef Energy A&B is largely part of the magic liquid potions I talked about in my post. Could it be beneficial? Sure..... Is it necessary? Absolutely not...... Are there other ways to obtain similar results? Most likely..... Is it safe in moderation? Probably.....
I have a 12" vlamingii tang that carpet bombs my reef every day. He looks like one of those huge airplanes dumping water to put out a forest fire. LOL Not long after that, my milli's will be super hairy. Recycled nori and mysis shrimp to feed my corals. Could this be similar to the "flock" Red Sea says is in part A???? Who knows? They won't tell us exactly what's in it. They say part B has the exact vitamins and MAA that are produced by zooxanthellae. Why would we need to spend money on this and dose it to our tanks when we have zooxanthellae living inside our corals that produce it for free??? Where's the data showing that elevating these nutrients over and above what the zooxanthellae produce is beneficial???
Acropora feed on tiny particles of organic matter. There are many different ways to provide that to our corals. Many people with lots of fish, simply feed the fish well and the enviable tiny particles of fish poo feed their Acropora. Others, with few fish my feed one of the manufactured dry coral foods, or supply frozen foods like rotifers. Bottom line is, if the coral is fed well, we don't need to maintain or dose things like PO4, NO3, or AA.
HTH
Peace
EC

 

[Ryan Hunter]

135 Gallon 72"x18"x24" 6 years old

Parameter levels:
Ca - 400ppm
Alk - 7.8-8.0
pH - 8.1-8.3
Mg - 1300
NO3 - rarely test anymore
PO4 - rarely test anymore
Salinity - 1.025

Lighting: ATI 8x80w Two bulbs ON 9am-11pm, remaining bulbs on 10am-8pm

Water Changes: 1 gallon per day (Apex Dos)

Controller: Apex

Dosing:
Calcium reactor

Flow: 2x Apex Wav running on pulse at 100% inverse

I had the most success when I stopped messing with things. I rarely test NO3 and PO4 anymore because I was always chasing numbers up and down and constantly taking away stability. I no longer dose anything or take any extra measures. I have tried many of common methods i.e. ZEO, carbon dosing etc. but never had any real success. Everybody always mentions patience in this hobby. I think my success started coming when I truley learned patience and just let the tank be and let things settle out instead of intervening.

Roughly 24" Red Planet

 

[pdiehm]

Acropora do have mouths, just like LPS, just on a much smaller scale. It is totally possible that you're seeing a feeding response in your stylo.
IMHO Reef Energy A&B is largely part of the magic liquid potions I talked about in my post. Could it be beneficial? Sure..... Is it necessary? Absolutely not...... Are there other ways to obtain similar results? Most likely..... Is it safe in moderation? Probably.....
I have a 12" vlamingii tang that carpet bombs my reef every day. He looks like one of those huge airplanes dumping water to put out a forest fire. LOL Not long after that, my milli's will be super hairy. Recycled nori and mysis shrimp to feed my corals. Could this be similar to the "flock" Red Sea says is in part A???? Who knows? They won't tell us exactly what's in it. They say part B has the exact vitamins and MAA that are produced by zooxanthellae. Why would we need to spend money on this and dose it to our tanks when we have zooxanthellae living inside our corals that produce it for free??? Where's the data showing that elevating these nutrients over and above what the zooxanthellae produce is beneficial???
Acropora feed on tiny particles of organic matter. There are many different ways to provide that to our corals. Many people with lots of fish, simply feed the fish well and the enviable tiny particles of fish poo feed their Acropora. Others, with few fish my feed one of the manufactured dry coral foods, or supply frozen foods like rotifers. Bottom line is, if the coral is fed well, we don't need to maintain or dose things like PO4, NO3, or AA.
HTH
Peace
EC

Gracias.

I'll keep feeding my fish more than I should then. They are fat, and active. My 3 tangs do carpet bomb the tank like your does. There's a lot of misinformation that you need to have 1ppm and untraceable amounts of PO4 in order to keep sps. I don't have anything that anyone would mistake for sensitive, but I also don't have a lot of livestock either. I have 4 or 5 corals, and 6 fish (3 tangs, 2 clowns, and a midas blenny) in my 120 gallon, plus I have an oversized skimmer pulling out nasty gunk.

 

[mcarroll]

https://www.sciencedirect.com/science/article/pii/S0966842X1500075X

Above is a link you may find interesting. Here's a quote from the link.
"Tropical reef-building corals commonly flourish in nutrient-poor environments. The contradiction of high coral productivity on the one hand and limited nutrient availability on the other hand has been coined the ‘Darwin Paradox’"
If these corals did "eat plenty of dissolved nutrients in the wild", we would not have the "Darwin Paradox".

(Hopefully I'm not misunderstanding you here.....let me know!!) :)

Feeding is good, but Darwin was not privy to the last 135 years worth of research. ;)

The very next line of the article:

The highly efficient uptake and recycling of nutrients by coral reef organisms can help to explain this paradox [3, 4].

In other words, no paradox – not with the corals anyway.

Corals ancestral state is what you're describing where feeding is the main and only concern. They were bottom-of-the-sea dwelling micropredators – more or less plain and simple. They didn't exist outside of a consistent stream of particulate foods.

Lose their ability to use dissolved nutrients with such amazing efficiency and they would lose the ability to exist in most places that reefs exist – there is not a sufficient food supply, so it would be back to the deep where marine snow is plentiful.

If you look at lots of coral reefs they are not homogenous in their habitat. Plenty are in high nutrient areas. If this was a problem, they would not be there.

Check out the rest of that article as it goes into lots of detail on why Darwin's Paradox doesn't really exist.

For example:

Nitrogen uptake and symbiont control in the coral holobiont
The coral holobiont is highly efficient in the assimilation of nitrogen. Heterotrophic feeding by the coral can meet a large part of its nitrogen requirements if sufficient food is available [24. In addition, corals acquire nutrients from their symbiotic algae from the genus Symbiodinium. This symbiotic relationship forms the foundation of coral holobionts and shallow-water coral reefs. In this association, the phototrophic dinoflagellates provide photosynthates to the coral host. However, the translocated photosynthates have been referred to as ‘junk food’ because they show a high C:N ratio and therefore require additional nitrogen supplementation to sustain coral growth [25. The symbiotic algae benefit from inorganic nutrients which are released as metabolic waste products by the host [5, 26] Their capacity for efficient uptake and utilization of dissolved inorganic nitrogen (DIN) facilitates the acquisition of nitrogen from the surrounding seawater. Although both the coral host and associated Symbiodinium have the enzymatic machinery to incorporate ammonium, the algae account for most of the uptake of dissolved inorganic nitrogen from the environment, mainly in the form of ammonium (NH4+) and nitrate (NO3−) [27.

Nitrogen fixation
Coral reefs are net sources of fixed nitrogen [42. Nitrogen fixation, in other words the conversion of elemental dinitrogen (N2) into ammonium, is associated with many substrates (e.g., sand, coral rock, and rubble) and benthic organisms (e.g., corals, macroalgae, and sponges) [21, 43]. This input of new fixed nitrogen into the reef ecosystem helps to sustain net productivity under oligotrophic conditions and to compensate for net nitrogen export from the system, for instance by currents [44. Nitrogen fixation in hermatypic corals has been reported for several different species [45, 46, 47, 48], suggesting a high relevance of this process for the coral holobiont. However, reported nitrogen fixation rates in corals are about a magnitude lower than those found in reef sediments and bare rock [43. Hence, corals appear to be minor contributors to the overall nitrogen budget of coral reefs.

Dissolved nutrient utilization to supplement feeding is part and parcel to being a coral "these days". ;)

Nothing controversial or problematic about it, per se.

The trouble comes with human disturbance most of the time...when the natural nutrient patterns are disturbed by excessive inputs...often of nitrogenous and carbonaceous compounds.

The most common side-effect of that for reefs seems to be severe PO4 limitation. When real PO4 limitation happens that's when the excrement hits the fan. Eutrophication.

(BTW, that's one of my favorite articles. I saved that to my blog last May with comments you can see here: Nitrogen cycling in corals: the key to understanding holobiont functioning?)

From pdiehm's last post....I suspect this is what you're reacting against:

There's a lot of misinformation that you need to have 1ppm and untraceable amounts of PO4 in order to keep sps.

Folks commonly (seems like every new tank that comes along) go down this road, take it way to seriously and way to far, and they end up sucking every last ion of N or P out and saturating the system with organic carbon in the process.

Folks who don't do that should never have any cause to dose any liquid nutrients.

(Folks who don't do that seem to be as rare as hens teeth these days.)

SPS corals do not have mouths

They have mouths on every polyp, but that doesn't even begin to tell the story. ;)

Check out:
Extracoelenteric zooplankton feeding is a key mechanism of nutrient acquisition for the scleractinian coral Galaxea fascicularis
(click through to the PDF on these links if you wanna read the whole thing)

Their entire body can be considered a mouth, for all intents and purposes.

Internal and external feeding on zooplankton may provide scleractinian corals with important nutrients. […] To quantify the dynamics of zooplankton capture, digestion and release for a scleractinian coral, we performed detailed video analyses… On average, 98.6% of prey captured was not ingested. Instead, prey items were clustered into aggregates that were digested externally by mesenterial filaments.

 

[pdiehm]

so I am understanding, and I'm going to use my tank as an example.

My NO3 and PO4 is 2ppm and 0.0-0.01 on average. I'm running at about 9dkh, which from what I've read in this thread may be a touch too high with how low my nutrients are?

I do run 1/2c Rox 0.8 in the reactor, flow is about 1/2 throttled from the MJ1200.

My salt is the RSCP (it's what I have and then I have another box of regular IO). Should I stop doing weekly 10% water changes, and move to bi-weekly or monthly?

My frags are very small, and over the course of the week the Alk fell 0.7 (9.0 to 8.3). Water change brought it back to 8.7-8.8. Was advised to dose 20ml per day of 2 part (to start) to reduce that swing, and that happened, but with every change, the alk climbed to say 9.2, then to 9.5.

I'm trying to do what's best for the corals. I also run filter socks, which I'll probably take off line unless I'm going to be stirring things up (once a week).

Tips/advice greatly and always appreciated.

 

[mcarroll]

You need to use either a dosing calculator like the Reef Chemistry Calculator or the instructions on the back of the bottle to calculate a correct dose that matches your test results.

If you're doing anything OTHER than water changes to limit nutrients then stop.

Otherwise, yes I'd hold off on water changes until your nutrient levels dictate that you do one. Let PO4 come up to ≥0.03 ppm at least.

 

[pdiehm]

Thank you. the whole water changing while dosing to keep things stable has confused the hell out of me.

So is my alkalinity of 9 ok for my levels? If yes, I need to figure how, when I do a water change to balance the alk change with the change in the alkalinity of the new water. Unless I just shut the doser off for a day or 2 following a water change then turn it back on to maintain that 9ish level .

I'm probably way overthinking this.

 

[Elegance Coral]

(Hopefully I'm not misunderstanding you here.....let me know!!) :)

Feeding is good, but Darwin was not privy to the last 135 years worth of research. ;)

The very next line of the article:
The highly efficient uptake and recycling of nutrients by coral reef organisms can help to explain this paradox [3, 4].

In other words, no paradox – not with the corals anyway.

The paradox is still there. The fundamental principles of the paradox haven't changed. We have solved the paradox, but not by correcting something that was wrong with it. We still have on one hand, an explosion of life on and around coral reefs, and on the other, a seemingly deficient nutrient supply to support it. This hasn't changed. What has changed, is our understanding of how these organisms can flourish in an environment that is so deprived of life sustaining nutrients.
In the statement you quoted above, they just use the word "uptake". They do not define that process here. They're simply making the point that the corals ability to obtain/uptake/acquire and recycle nutrients is how we can explain the paradox. They are not suggesting that the coral is dependent on dissolved nutrients.

Corals ancestral state is what you're describing where feeding is the main and only concern. They were bottom-of-the-sea dwelling micropredators – more or less plain and simple. They didn't exist outside of a consistent stream of particulate foods.

I think here is where we're not communicating well. :)
I'm not talking about azooxanthellate corals. I'm talking about SPS/reef building stony corals. When I talk about their dependence on food, I'm not suggesting that it even comes close to the food requirements of azooxanthellate corals. SPS/reef building stony corals have, in comparison, very little demand for nutrition from outside sources. Solid or dissolved nutrients. However, on the nutrient demand they do have, of the environment around them, the vast majority is met through feeding on solid organic particles. With very little, if any, demand for dissolved nutrients in the water.

Lose their ability to use dissolved nutrients with such amazing efficiency and they would lose the ability to exist in most places that reefs exist – there is not a sufficient food supply, so it would be back to the deep where marine snow is plentiful.

Can you post a link to support this conclusion? What dissolved nutrients?? There is very little in the way of nutrition dissolved in the water around healthy growing coral reefs. Hence the paradox. There is also very little in the way of zooplankton or solid organic particles to feed on. However, the abundance of life here is the other side of that paradox. Life that produces tiny little larvae. One tiny bug or larvae captured by a coral polyp would be a highly concentrated packet of energy and nutrition. While reef building stony corals and their zooxanthellae have very little demand for nutritional input from outside sources, when compared to most other life on this planet, they do require some. The bulk of which is provided by feeding on solid organic particles. Not through the uptake/absorption/concentration of dissolved inorganics (Po4, NO3.....) in the water. It is the lack of nutrients in the water that led to the evolution of the symbiosis between these corals and their zooxanthellae in the first place.

If you look at lots of coral reefs they are not homogenous in their habitat. Plenty are in high nutrient areas. If this was a problem, they would not be there.

We are in the SPS forum. In a thread titled "How to successfully keep SPS corals". I assumed we were talking about SPS/reef building stony corals.
You are correct that there are many different types of coral reefs living under many different conditions. As those conditions change, the species living there also change. Out in the middle of the south pacific, largely away from man's influence, we have pristine waters with very little nutrient content, and healthy growing coral reefs. Virtually every square inch of these reefs may be covered in a layer of living coral tissue. As nutrient levels in the water climb, the reefs change. Reef building/SPS corals begin to suffer. Bald patches of limestone/coral skeleton begin to appear on the reef. Other organisms that once weren't doing very well, like gargonians, sponges, sea fans, and some LPS, begin to prosper. As nutrient levels continue to climb, different species of algae may begin to appear. SPS/reef building stony corals really begin to suffer and decline in numbers. When these corals are gone, the reef is no longer growing. It is slowly eroding. What we do not have, is healthy growing SPS coral reefs in high nutrient waters, or reefs covered in sponges, algae, and gargonians in very nutrient poor waters.

Check out the rest of that article as it goes into lots of detail on why Darwin's Paradox doesn't really exist.

I think you're missing the whole point of Darwin's Paradox. Yes, it has been solved. Yes, we can explain it. What it does, is show us that, even in an environment that is sooo devoid of life sustaining nutrients, life can still find a way to flourish. That is the amazing part of Darwin's paradox.

Dissolved nutrient utilization to supplement feeding is part and parcel to being a coral "these days". ;)

Exactly..... :) When dissolved nutrient utilization does occur, it is simply a supplement to feeding. Not the other way around.

The trouble comes with human disturbance most of the time...when the natural nutrient patterns are disturbed by excessive inputs...often of nitrogenous and carbonaceous compounds.

Again, we agree!!!!!! :)

The most common side-effect of that for reefs seems to be severe PO4 limitation. When real PO4 limitation happens that's when the excrement hits the fan. Eutrophication.

UUUMMMM?????? Can you post something to show how PO4 limitation can lead to euthrophication? Euthrophication is caused by PO4, and other nutrient, abundance. Not limitation.

Peace
EC

 

[Elegance Coral]

If you're doing anything OTHER than water changes to limit nutrients then stop.

Otherwise, yes I'd hold off on water changes until your nutrient levels dictate that you do one. Let PO4 come up to ≥0.03 ppm at least.

Just throwing this out there.
I know this is the common, or close to standard, advice given out on forum boards these days. My question is, why??

Why raise the inorganic PO4 level in the open water, where it is accessible by problem causing algae and microbes? If the goal is to provide PO4 to the coral, why not simply feed the coral directly with organically bound PO4, that is not accessible by problem causing algae and microbes??

Peace
EC

 

[mcarroll]

The paradox is still there. The fundamental principles of the paradox haven't changed.

Is a paradox still a paradox when you can understand and explain it and there's no longer a contradiction?

I think that's when we stop calling it a paradox and instead we just say "we understand now".

In the statement you quoted above, they just use the word "uptake".

I'm using "uptake" how they and other articles use it....and even how normal people use it.

It's a common word, not science jargon that needs explaining, and means just what the dictionary says: "The act of taking up or making use of something that is available."

I think here is where we're not communicating well. :)
I'm not talking about azooxanthellate corals.

You are right – I didn't say anything about that.

---------------------------
The quote below seems to address your point of view, addresses both modes of nutrition and hopefully will lay this to rest.

The dual character of corals, that they are both auto- and heterotrophs, was recognized early in the twentieth Century. It is generally accepted that the symbiotic association between corals and their endosymbiotic algae (called zooxanthellae) is fundamental to the development of coral reefs in oligotrophic tropical oceans because zooxanthellae transfer the major part of their photosynthates to the coral host (autotrophic nutrition). However, numerous studies have confirmed that many species of corals are also active heterotrophs, ingesting organisms ranging from bacteria to mesozooplankton. Heterotrophy accounts for between 0 and 66% of the fixed carbon incorporated into coral skeletons and can meet from 15 to 35% of daily metabolic requirements in healthy corals and up to 100% in bleached corals. Apart from this carbon input, feeding is likely to be important to most scleractinian corals, since nitrogen, phosphorus, and other nutrients that cannot be supplied from photosynthesis by the coral’s symbiotic algae must come from zooplankton capture, particulate matter or dissolved compounds. A recent study showed that during bleaching events some coral species, by increasing their feeding rates, are able to maintain and restore energy reserves.

I've attempted to gather all your claims together so they're easier to see and think about....

They're simply making the point that the corals ability to obtain/uptake/acquire and recycle nutrients is how we can explain the paradox. They are not suggesting that the coral is dependent on dissolved nutrients.

According to them, eating (heterotrophy) can account for up to between 15-35% of their metabolic carbon requirements.

When I talk about their dependence on food, I'm not suggesting that it even comes close to the food requirements of azooxanthellate corals. SPS/reef building stony corals have, in comparison, very little demand for nutrition from outside sources. Solid or dissolved nutrients.

You downplay it, but they think it's likely to be important.

They do not pin it on feeding as you do....as in reality it does come from dissolved sources, among others.

There is very little in the way of nutrition dissolved in the water around healthy growing coral reefs. Hence the paradox. There is also very little in the way of zooplankton or solid organic particles to feed on.

Why would corals EVER starve during bleaching if dissolved nutrients weren't keeping them alive in the first place?

How could corals EVER survive bleaching if there weren't copious particles to feed on?

While reef building stony corals and their zooxanthellae have very little demand for nutritional input from outside sources, when compared to most other life on this planet, they do require some. The bulk of which is provided by feeding on solid organic particles. Not through the uptake/absorption/concentration of dissolved inorganics (Po4, NO3.....) in the water.

What is the comparison that you're making with other forms of life? Do you have a reference on that?

From the above article quote, obviously dissolved organics are involved in a big way.

What we do not have, is healthy growing SPS coral reefs in high nutrient waters, or reefs covered in sponges, algae, and gargonians in very nutrient poor waters.

That's a platitude and SPS is a meaningless term. Either we're talking stony tropical corals or we're talking something else. And stony tropical corals can be found in high and low nutrient reefs. It's hard to believe anyone would argue this.

Look up what corls live in lagoons. Look up what corals live in fringing reefs. Tell me when you start looking that you don't find stony corals thriving in every habitat.

I'll even give you a tool that makes it easy to seach by terms like "lagoon" or search on a map to find a geography that you want to look at: All Fact Sheets at the Corals of the World database that Veron assembled.

Exactly..... :) When dissolved nutrient utilization does occur, it is simply a supplement to feeding. Not the other way around.

This is not consistent with anything I've read, nor with bleaching behavior I've seen, including mortality and survival.

Corals don't die when bleached if they have a consistent food source they are able to depend upon. But based on photo evidence, corals DO die from bleaching frequently. This would lead one to believe that they were subsisting primarily on dissolved nutrients.

But someone else may have said it better after a long paper designed to place emphasis on the role of heterotrophy:

...the relative importance of both autotrophic and heterotrophic carbon to a coral's energetic needs should be considered as a continuum, from 100% photoautotrophy to 100% heterotrophy.

(doi:10.1016/j.jembe.2008.09.015)

Pls recall that all I originally said is that corals in the wild "eat" plenty of dissolved nutrients. They do. And so do corals in captivity.

Now lets tackle the myth of "burnt tips". ;) Are you carbon dosing?

 

[Elegance Coral]

Now lets tackle the myth of "burnt tips". ;) Are you carbon dosing?

The rest of that just got a little to hairy for me, so I'm just letting that go.
You do have my curiosity up on the burnt tips thing though.
No.... I do not carbon dose. I maintain undetectable (with aquarium testing equipment) PO4 and NO3 without carbon dosing so I don't see the need.
Why is burnt tips a myth????

 

[pdiehm]

So, as one of them, let's try it and see things, I have some Brightwell Marine Snow that I drop into my biocube lps tank once or twice a week to broadcast feed (mainly my candy canes, who puff up like balloons and send out feeder tentacles), I shut the pumps off in my 120. I target fed my stylophora, my Cliffs Acro, the Slimer, Nauti and Sunset monti. The results were...wow.

The stylophora had so much fuzz going on, it looked like a peach. I've never seen the polyps that far extended. I also noticed that there is signs of growth. Way cool. The Slimer didn't have the same reaction but you could see some strings coming out. The cliff's acro looks like a ball of yarn, the Nauti didnt' show anything, and the sunset had strings coming out, and most of the blue polyps were out.

That said, I ordered some Coral Frenzy, and will feed that to the sps once a week or so. I was under the impression that I didn't have to feed them, but it looks like I do, at least until I have more of a fish bioload in my tank (6 fish in a 120 gallon isn't a lot...at least to me).

 

[Futuretotm]

@Elegance Coral

I keep hearing that most of the worlds corals are in nutrient deficient areas (and some are not).
Isn't it true that the coral feed off the local fauna? Hence the above is not really true?? The local poop/other organic breakdown is what feeds the coral, hence when we measure the water either up or down flow from a large coral head/area we get zero N&P? Even local N&P are not registered since the "poop" is picked up ASAP and incorporated + any leftovers are swept away with the tide and diluted with the amount of volume of the ocean

just a thought....

 

[Elegance Coral]

@Futuretotm
Nice to see a local on here. :) I'm in Lakeland.....

Yes.... You're pretty much correct. It can get much more complicated than that, and there are many pieces of this puzzle, but it sounds like you pretty much got it.

What left the scientists scratching their heads, early on, was the fact that they could drift around in the open ocean for days, weeks, or months, and see very little, if any, signs of life. Then drift over a sea mount and see an explosion of life just below the surface. Fish of all sizes and shapes and colors. Coral and sea anemones flourishing. Then they could drift a few more yards and be right back in a sea of nothingness. It didn't make sense. How could a seemingly sterile, oceanic desert, give rise to such an abundance and diversity of life???

There was one evolutionary leap that made all of this possible. That was when a zooxanthellae took up residence inside a coral. Before this, coral could not survive in these areas. Without coral, not much else could survive either. Corals couldn't survive because there isn't enough energy/nutrition in the water to support them. Algae cells, like zooxanthellae, couldn't survive in large numbers because there isn't enough dissolved fertilizers, like nitrogen and phosphorus, in the water to sustain them. When these two teamed up, everything changed. A healthy coral could now receive energy, nutrition, sugars, carbohydrates, directly from it's zooxanthellae. This meant that the coral could now survive where these resources, from the surrounding environment, were not in great supply. The zooxanthellae could now obtain its fertilizer (nitrogen and phosphorus) from the waste of it's coral host. The zooxanthellae were no longer dependent on the insignificant amount of fertilizer dissolved in the open ocean. Through this tight sharing and recycling of nutrients, together they could flourish, where alone they have no chance.

Once you have life like this in an area, it typically gives rise to other forms of life that utilize this life for it's own organic food, shelter, and survival. Microbes feed on coral slime. Other tiny creatures feed on these microbes. Larger creatures feed on these creatures. Others may feed on the coral itself. Still larger creatures feed on these creatures. Before long, we have what we now call coral reefs with their huge diversity of life. Even though there isn't enough nutritional input to sustain it alone. All of these animals play a role in sharing and recycling the precious few nutrients they have. "Poop", plays a huge role in all of this. One organism's waste is another organism's feast. A grouper may feed on a parrot fish, then poop. Other fish may feed on this grouper poop, then poop themselves. Still smaller fish may feed on this poop, and poop themselves. Then a coral polyp may feed on this poop. A parrot fish may then feed on this coral polyp, then be eaten by a grouper, and the process continues. Through this process, these organisms can trap and recycle the same nutrients over and over and over and over again on the coral reef. This, and other factors, leaves the whole community with very little dependence on nutritional input from outside sources, or nutrients dissolved in the open water. The whole system can survive and flourish even though they live in very nutrient poor waters. In fact, they depend on living in these nutrient poor waters. When nutrients in the water rise, the whole system is disrupted, and coral reefs die.

This is why I am firmly against the notion of maintaining X amount of, or dosing, inorganic nitrogen and phosphorus into the water of a system that's dedicated to keeping SPS/ reef building stony corals. None of the links, or quotes, in this thread, or any other thread, and none of the countless research papers I've read, show that these corals are dependent on inorganics like N and P in the open water. Not one. These animals are dependent on N and P, just like the rest of us animals on the planet. However, that does not imply that these healthy corals are receiving these nutrients through inorganic dissolved substances in the water. They live in an environment where these resources are scarce to say the least, and where one tiny organic particle, or organism, captured as food, will have a concentration of nutrients that far exceed the water around it. A healthy coral on a coral reef would have to process vast quantities of water to equal the nutritional value of one tiny little copepod. These corals rely on their zooxanthellae for the vast majority of their energy requirements, and feeding on organic particles for the vast majority of their nutrition requirements for growth and reproduction. We have all kinds of literature to show that these corals suffer when N and P are elevated in the water, but nothing to show that these corals are adversely effected when they are low, or undetectable with our test kits. Providing the corals are fed well.

Peace
EC

 

[mcarroll]

I'm not sure I get what the confusion over nutrients is...

Or if there's no confusion, then I don't understand what's being suggested/asserted.

The Treatment
Folks in this thread who add N and/or P fertilizers are generally doing it because their system is deficient. (In many cases because it has been artificially made deficient.)

These folks see immediate improvement in their corals when fertilizers are added. Problem solved.

The Ecology
This doesn't have any direct bearing on whether corals ever eat. And it certainly doesn't imply that they never eat. It's just a fix to a problem.

For what it's worth, corals use of dissolved nutrients has been shown to scale inversely with availability of food particles.

It can be thought of like this: The more they eat, then less fertilizers they will use. The less they eat, the more fertilizers they will use.

 

[Scott.h]

@Futuretotm
Nice to see a local on here. :) I'm in Lakeland.....

Yes.... You're pretty much correct. It can get much more complicated than that, and there are many pieces of this puzzle, but it sounds like you pretty much got it.

What left the scientists scratching their heads, early on, was the fact that they could drift around in the open ocean for days, weeks, or months, and see very little, if any, signs of life. Then drift over a sea mount and see an explosion of life just below the surface. Fish of all sizes and shapes and colors. Coral and sea anemones flourishing. Then they could drift a few more yards and be right back in a sea of nothingness. It didn't make sense. How could a seemingly sterile, oceanic desert, give rise to such an abundance and diversity of life???

There was one evolutionary leap that made all of this possible. That was when a zooxanthellae took up residence inside a coral. Before this, coral could not survive in these areas. Without coral, not much else could survive either. Corals couldn't survive because there isn't enough energy/nutrition in the water to support them. Algae cells, like zooxanthellae, couldn't survive in large numbers because there isn't enough dissolved fertilizers, like nitrogen and phosphorus, in the water to sustain them. When these two teamed up, everything changed. A healthy coral could now receive energy, nutrition, sugars, carbohydrates, directly from it's zooxanthellae. This meant that the coral could now survive where these resources, from the surrounding environment, were not in great supply. The zooxanthellae could now obtain its fertilizer (nitrogen and phosphorus) from the waste of it's coral host. The zooxanthellae were no longer dependent on the insignificant amount of fertilizer dissolved in the open ocean. Through this tight sharing and recycling of nutrients, together they could flourish, where alone they have no chance.

Once you have life like this in an area, it typically gives rise to other forms of life that utilize this life for it's own organic food, shelter, and survival. Microbes feed on coral slime. Other tiny creatures feed on these microbes. Larger creatures feed on these creatures. Others may feed on the coral itself. Still larger creatures feed on these creatures. Before long, we have what we now call coral reefs with their huge diversity of life. Even though there isn't enough nutritional input to sustain it alone. All of these animals play a role in sharing and recycling the precious few nutrients they have. "Poop", plays a huge role in all of this. One organism's waste is another organism's feast. A grouper may feed on a parrot fish, then poop. Other fish may feed on this grouper poop, then poop themselves. Still smaller fish may feed on this poop, and poop themselves. Then a coral polyp may feed on this poop. A parrot fish may then feed on this coral polyp, then be eaten by a grouper, and the process continues. Through this process, these organisms can trap and recycle the same nutrients over and over and over and over again on the coral reef. This, and other factors, leaves the whole community with very little dependence on nutritional input from outside sources, or nutrients dissolved in the open water. The whole system can survive and flourish even though they live in very nutrient poor waters. In fact, they depend on living in these nutrient poor waters. When nutrients in the water rise, the whole system is disrupted, and coral reefs die.

This is why I am firmly against the notion of maintaining X amount of, or dosing, inorganic nitrogen and phosphorus into the water of a system that's dedicated to keeping SPS/ reef building stony corals. None of the links, or quotes, in this thread, or any other thread, and none of the countless research papers I've read, show that these corals are dependent on inorganics like N and P in the open water. Not one. These animals are dependent on N and P, just like the rest of us animals on the planet. However, that does not imply that these healthy corals are receiving these nutrients through inorganic dissolved substances in the water. They live in an environment where these resources are scarce to say the least, and where one tiny organic particle, or organism, captured as food, will have a concentration of nutrients that far exceed the water around it. A healthy coral on a coral reef would have to process vast quantities of water to equal the nutritional value of one tiny little copepod. These corals rely on their zooxanthellae for the vast majority of their energy requirements, and feeding on organic particles for the vast majority of their nutrition requirements for growth and reproduction. We have all kinds of literature to show that these corals suffer when N and P are elevated in the water, but nothing to show that these corals are adversely effected when they are low, or undetectable with our test kits. Providing the corals are fed well.

Peace
EC

Although I don't use the same strategy as you, I can appreciate what you're saying. I don't think adding N or P alone will make or break someone from being able to keep sps, but I think there are a couple of things to be pointed out. I do think dosing for those running low levels offers an extra blanket of protection. I'd also argue that I feel the corals look a bit brighter and healthier when a measurable amount can steadily be detected. This could hold true for those corals in nature as well. But for someone reading this thread starting out trying to understand what's going on I think it's beneficial to explain what you said a bit further. If you have a mature system (obviously you do) then you have a mature biological environment established at multiple levels reguarding your food chain argument. So for someone that has imature dry rock (lacking important bacteria), or a small bio load of fish, or lacking organisms in that food chain, or small/few frags that won't release much volume of slime, one might wonder why they can't support certain corals running an almost starved environment and left scratching their heads. It's not as simple as adding fresh salt water with "perfect" near ocean perameters, light, and flow and expecting the success that you have at undetectable nutrient levels. I do think that if you feed heavy (which you obviously do), and have a system of still being able to keep those nutrient levels ultra low, that feeding heavy is an appropriate method giving the corals what they need. One might wonder what would be considered a heavy feeding also. To me that means enough food (small) particles for each coral to regularly obtain. For a newcomer to the hobby their version of a heavy feeding into a fairly new system could cause other problems if not understood. But I'd also point out that running near or undetectable levels at that level we can't really measure how low that level really is. The newer the tank the more critical I feel that is, as it would be very easy to go too low for someone that didn't understand these things. Ultimately our tanks are very different then the ocean. I'd also like to think that we are able to, or very close to being able to keep certain corals in captivity that may not be able to survive in the ocean. Those reasons could be anything from pollution to temperature, or.. something else.