Optimal phosphate level? (Mixed Reef)

[living_tribunal]

The ocean would tell you so. The places where most of our corals are collected are about 1-2 ppb of phosphate and they are not limited in anyway - some grow at an outstanding clip while also being out of the water for hours at a time (there is not anything for them to catch or eat in these places, so they get what they get from the sun and the elements in the water). I am afraid that wanting more building blocks is a recent human phenonomen likely taking the blame for inferior biodiversity, or something else in modern husbandry, in most tanks set up in the last five years, or so.

With your land plant analogy, remember what happens if you keep with that surplus all of the time... they suffer. Your analogy is a sparse occurrence... maybe once or twice a year with a fertilization. Would anybody care to succumb these plants to 24x7 higher levels of building blocks? Anybody spill some fertilizer on your lawn and see what happens? It is probably non-sequitur between plants and corals anyway.

My question still stands, in actual science and the rest of nature, what evidence is there that a larger surplus is better than a smaller one? Do you need 100 cheeseburgers in the car when 1 will fill you up? Do you need more fertilized that what a plant can process, or just enough? There is evidence that higher levels are harmful to all living tissue at various intervals and that a low, but enough balance is what matters.

I get and agree with there being some limit on the absolute level of phosphate that a coral simply can’t absorb but most all of us hobbyists are nowhere near that limit.

The rather dramatic increase in Acropora skeletal growth at the .5 phosphate level compared to lower levels is something that can’t be ignored.

This is an isolated experiment in an aquarium setting so can be replicated and we can deduce the only variable that changed were the phosphate levels. Is it that phosphates directly impacted the growth or do they impact something else that spurs the growth? That we don’t know.

 

[TexasReefer82]

The ocean would tell you so. The places where most of our corals are collected are about 1-2 ppb of phosphate and they are not limited in anyway - some grow at an outstanding clip while also being out of the water for hours at a time (there is not anything for them to catch or eat in these places, so they get what they get from the sun and the elements in the water). I am afraid that wanting more building blocks is a recent human phenonomen likely taking the blame for inferior biodiversity, or something else in modern husbandry, in most tanks set up in the last five years, or so.

With your land plant analogy, remember what happens if you keep with that surplus all of the time... they suffer. Your analogy is a sparse occurrence... maybe once or twice a year with a fertilization. Would anybody care to succumb these plants to 24x7 higher levels of building blocks? Anybody spill some fertilizer on your lawn and see what happens? It is probably non-sequitur between plants and corals anyway.

My question still stands, in actual science and the rest of nature, what evidence is there that a larger surplus is better than a smaller one? Do you need 100 cheeseburgers in the car when 1 will fill you up? Do you need more fertilized that what a plant can process, or just enough? There is evidence that higher levels are harmful to all living tissue at various intervals and that a low, but enough balance is what matters.

Define "better than". Does that mean faster growth? Color? Etc.

Natural reefs grow in a variety of phosphate concentrations.

In general I certainly agree that wild reefs grow extremely well and quickly in much lower phosphate concentration that we maintain in our tanks. However, I also know that if I let the concentration of phosphate and nitrate in my tank get as low as it is on wild reefs my Corals suffer. And when I maintain the levels higher, for example a few PPM nitrate and 0.05 phosphate, all my acros are much happier.

Why do the corals in my tank not respond to natural levels of nutrients in the same way the Corals in the wild do?

 

[jda]

Has anybody taken a trip to the coral sea or coral triangle? There are building-block rich areas where many corals live... NPS, softies, nems, clams, but acropora do not hang around these areas. The acropora grow in the open ocean with no access to much if any food (according to the biologist on our trip). Keep in mind that these "rich" areas are still pretty low for our tanks, but high for the ocean. Sometimes, they sit out of water for hours and hours and the collectors that were with us clipped them standing in waist deep water under super intense sunlight.

I mostly think that most modern tanks are devoid of any true bio and microfauna diversity since live rock stopped being used and that lighting is not as high of quality as it used to be... this is too simple, but you get the point. I also have this theory in post 15-17 in this thread that some smart people are looking into:

Crunching Numbers at LFS - Radion, Nitrate, Phosphate

Purchased some corals at the LFS today, and took the opportunity to evaluate lighting and nutrients. They use Radion G4s for lighting. PPFD (or PAR, if you will) ranges from 75 to 175 micromole/m2/sec. Photoperiod is 11 hours at this spectral quality: UV-A 2.8% Violet 19.6% Blue 67.8%...

www.reef2reef.com

 

[living_tribunal]

Has anybody taken a trip to the coral sea or coral triangle? There are building-block rich areas where many corals live... NPS, softies, nems, clams, but acropora do not hang around these areas. The acropora grow in the open ocean with no access to much if any food (according to the biologist on our trip). Keep in mind that these "rich" areas are still pretty low for our tanks, but high for the ocean. Sometimes, they sit out of water for hours and hours and the collectors that were with us clipped them standing in waist deep water under super intense sunlight.

I mostly think that most modern tanks are devoid of any true bio and microfauna diversity since live rock stopped being used and that lighting is not as high of quality as it used to be... this is too simple, but you get the point. I also have this theory in post 15-17 in this thread that some smart people are looking into:

Crunching Numbers at LFS - Radion, Nitrate, Phosphate

Purchased some corals at the LFS today, and took the opportunity to evaluate lighting and nutrients. They use Radion G4s for lighting. PPFD (or PAR, if you will) ranges from 75 to 175 micromole/m2/sec. Photoperiod is 11 hours at this spectral quality: UV-A 2.8% Violet 19.6% Blue 67.8%...

www.reef2reef.com

Any response to the study on the correlation of significantly increased growth of Acropora under increased phosphate levels? I’m interested to hear your thoughts.

 

[Stigigemla]

Yes I have made about 20 dives in the Phillipines. But only in nutrient poor waters with Acropora, Millepora and similar corals.
Another hobby I have is gardening and plant collection. And there is another knowledge about habitat coming up.
The fact that a plant is growing in a very harsh environment does not mean that that species do best there. It generally depends more on the fact that other plants dont do well there so its a lot of free space.

I believe it is just the same with corals. Many Acropora has developed an ability to live in extreme nutrient poor waters. It does not mean that they do best there. It just means that they have free living space there because other corals or life starve worse there. I believe it is totally false to say that corals generally do best in nutrient poor waters. They are just fit to survive there. It is also false to say a corals do better when it is showing bright colors. I have not seen one single fact from the scientific papers I have read that has shown a connection between colors and well being of corals other than that fluorescent colors can protect against too strong light. And in the ocean corals take up nutrition by eating plancton. In the night usually a lot of plancton is rising towards the surface and provide corals with nutrition other than N and P solved in the water.

But. Just as well we can kill cattle by giving them to much growth hormones so they grow to death I believe that strong growth on a coral does not necessarily mean that it is healthier.

What levels of N and P that is the best is something we probably will argue about many years to come.
I believe in our home tanks there is an analogy to the wild but in a some different way. Our values in the tanks are not dictated by the corals although it is easy to believe that.
Our values in our home reefs are more dictated of the fact that we dont want cyano, dinos or green hair algae.

 

[jda]

Even if they ended up there because they had nowhere else to go (not likely, but let's go with it), they would have evolved to make the best of this place. Nature 101.

I fear that most of this is the hubris of man trying to reverse engineer nature with our puny intellects what time and evolution has already figured out which is right in front of us (if we choose to see it)... that nature got it right.

 

[TexasReefer82]

There's a lot of interesting information presented here. Living_tribunal's chart of coral branch length wrt to phosphate is really striking. However, I wonder what that coral actually looked like? Was it long and spindly with a weak skeleton? Or were the branches thick and robust with well developed coralites and high skeletal density? Also, what were the nitrate at? Also striking is that growth at 0.09 and 0.2 (neither of which is exaclty Low by reefer standards) were the same but 0.5 was a huge difference. Something is definitely going on there.

I suspect that corals in the wild are eating way more (perhaps at all) than corals in our tanks. I suspect that their diet is where they acquire all the N and P that they need to grow so fast and healthfully in a water column that's severely oligotrophic. Maybe in our tanks we need elevated nutrient levels to compensate for lack of dietary nutrition. Not to mention all the other nutritional benefits of the planktonic diet wild corals would eat like fatty acids, minerals, vitamins, proteins, etc. Humans don't do well on a diet of sugar water, whey protein and multivitamin pills - we need a large variety of whole foods to get everything we need. Similarly, maybe corals need more than just the basic atomic building blocks (N, P, C, trace elements) dissolved in the water to be their best.

That said, I've seen absolutely thriving acropora filled tanks with both high phosphates (0.1-0.2) and high Nitrates (25); I've also seem them with high phosphate (0.1-0.2) but undetectable nitrate; and of course there are many successful ZeoVit tank where both are undetectable.

 

[living_tribunal]

There's a lot of interesting information presented here. Living_tribunal's chart of coral branch length wrt to phosphate is really striking. However, I wonder what that coral actually looked like? Was it long and spindly with a weak skeleton? Or were the branches thick and robust with well developed coralites and high skeletal density? Also, what were the nitrate at? Also striking is that growth at 0.09 and 0.2 (neither of which is exaclty Low by reefer standards) were the same but 0.5 was a huge difference. Something is definitely going on there.

I suspect that corals in the wild are eating way more (perhaps at all) than corals in our tanks. I suspect that their diet is where they acquire all the N and P that they need to grow so fast and healthfully in a water column that's severely oligotrophic. Maybe in our tanks we need elevated nutrient levels to compensate for lack of dietary nutrition. Not to mention all the other nutritional benefits of the planktonic diet wild corals would eat like fatty acids, minerals, vitamins, proteins, etc. Humans don't do well on a diet of sugar water, whey protein and multivitamin pills - we need a large variety of whole foods to get everything we need. Similarly, maybe corals need more than just the basic atomic building blocks (N, P, C, trace elements) dissolved in the water to be their best.

That said, I've seen absolutely thriving acropora filled tanks with both high phosphates (0.1-0.2) and high Nitrates (25); I've also seem them with high phosphate (0.1-0.2) but undetectable nitrate; and of course there are many successful ZeoVit tank where both are undetectable.

I have the links for the research posted on page 1 or 2. Higher phosphate levels do indeed increase calcification By total volume however at very high levels where the growth rate is extreme the skeleton is slightly more porous, by about 17%. While more porous, the net volume of new skeleton is much higher.

Yes, your corals can acclimate to high N and low P conditions as long as there is phosphate available in the column. But the research shows this is not optimal to maximize zooxanthelle efficiency.

While this does have an impact on large colonies establishing reefs, it’s not very important in our reefs where sps will never be near the same size. What else is striking is the polyp extension and color are greater in the high phosphate conditions. Higher phosphate levels tend to promote faster and more robust zooxanthelle densities leading to the faster calcification.

Also back to the other study I posted, corals will not tolerate high N and low P conditions but they thrive under low N and high P conditions. In fact, there was no difference in zooxanthelle densities and efficiency in the low N and high P environment compared to High N and high P (nutrient replenish condition).


There is a lot more to phosphates than is assumed under the current common narratives related to phosphates on the forum. Some can mock me for posting the research but I hope a few take interest to it and maybe do some personal exploring.

 

[living_tribunal]

There's a lot of interesting information presented here. Living_tribunal's chart of coral branch length wrt to phosphate is really striking. However, I wonder what that coral actually looked like? Was it long and spindly with a weak skeleton? Or were the branches thick and robust with well developed coralites and high skeletal density? Also, what were the nitrate at? Also striking is that growth at 0.09 and 0.2 (neither of which is exaclty Low by reefer standards) were the same but 0.5 was a huge difference. Something is definitely going on there.

I suspect that corals in the wild are eating way more (perhaps at all) than corals in our tanks. I suspect that their diet is where they acquire all the N and P that they need to grow so fast and healthfully in a water column that's severely oligotrophic. Maybe in our tanks we need elevated nutrient levels to compensate for lack of dietary nutrition. Not to mention all the other nutritional benefits of the planktonic diet wild corals would eat like fatty acids, minerals, vitamins, proteins, etc. Humans don't do well on a diet of sugar water, whey protein and multivitamin pills - we need a large variety of whole foods to get everything we need. Similarly, maybe corals need more than just the basic atomic building blocks (N, P, C, trace elements) dissolved in the water to be their best.

That said, I've seen absolutely thriving acropora filled tanks with both high phosphates (0.1-0.2) and high Nitrates (25); I've also seem them with high phosphate (0.1-0.2) but undetectable nitrate; and of course there are many successful ZeoVit tank where both are undetectable.

I’d also caution against the fallacy that many wild reefs are optimal. Many are depleted in nutrients, in fact, phosphate deficiency is a key variable currently for many wild reefs disappearing. There is of course more than just phosphates taking place but much of what we do in a reef is more optimal than is common in wild reefs. Corals are fantastic at adjusting to their environments, which is why reefers have success with a wide array of set ups. I do believe there are ranges where corals can perform best both immediately and in the long run. Wcience is only beginning to unravel those answers however with phosphates being just a small factor.

We need to think more critically about what constitutes optimal, the answer can be a bit subjective. We should also not divide what parameters are best into wild vs aquarium and instead hone in on specific variables regardless of what the location or environment is.

 

[TexasReefer82]

I prepared this table to summarize the results of the Euphyllia paper and also to convert all the values into ppm so that we can compare to our own systems. An interesting note is that the paper mentions that 0.3uM or 0.028ppm PO4 is approximately the critical threshold above which excess NO3 is not detrimental.

Beneath the values from the paper I listed the values of some tanks that I know personally as well as the values of some contributors to this thread: jda and glennf. All these tank grow very happy acropora with wildly different nutrient levels. Amazingly, every hobbyist tank listed maintains PO4 at or above the critical threshold - except for jda who maintains an N ratio of approximately 20, which is also consistent with what the paper states is a healthy ratio. So perhaps there are indeed multiple ways to grow the coral.

The next question I have is exactly the same as jda's: what's the value of raising nitrate to 25 with a phosphate of 0.1? Would nitrate at 0.5ppm work just as well while also giving a more favorable Nitrogen limited ratio? I'll say this about the display tank at my local reef store - it's fantastic! Their acropora specimens are the epitome of health. No one can see that tank and say that 25NO3/0.1PO4 is bad for coral. However, they also blast it with light, 900 PAR at the top of the rocks, and they admit that with nutrients that high the PAR is necessary to bring out the colors otherwise they're just brown. Jda, the lighting consists of 3x400 Radiums plus 6xRadion fixtures (not sure which generation but it's probably the latest, knowing them).

higher nutrients - higher PAR?; lower nutrients - lower PAR? all as long as the N/P ratio is within a healthy range and critical thresholds are met???

 

[jda]

The highest PAR is in the ocean and the N and P are the lowest there. They are also very low in my tank where I use high PAR MH all over the tank. I don't think that there is much of a correlation here, but who knows... There might be an inverse correlation where

In that tank, I would want to see a plethora or echinata and smooth skins thriving and growing well with 25 nitrate (not one, but a lot), as well as some others. There are plenty of acropora that do not mind 25 nitrate, but also plenty that would have been long dead - it is not what you see in some of these tank, but what you do not see. People post their heavy-tenuis tanks with higher N and P, but these will grow with 50+ nitrate. It is important to pay attention to what is in the tanks, but this is next-level type of stuff for most people and very hard to pay attention to. I do not know if I posted this here, but Ross had acropora thriving in his very high N and P tank, but he also had tons of deaths that you would expect from stuff that could not handle it - the deaths get overlooked and they very much matter.

I will say that I can grow any acropora at any time. I do not have species, like Purple Monster or some other, that I cannot keep like some. I will bet that most people who are NSW level can do the same. Some cannot keep Carduus or Echinata... a lot of this has to do with building blocks (probably lighting too, but let's don't get into this... it is never one thing, right?). I think that it should be asked to people who have Very Happy Acropora which acropora that they have tried that have not been happy - I have no doubt that the stuff that survives is happy.

 

[Scrubber_steve]

Any response to the study on the correlation of significantly increased growth of Acropora under increased phosphate levels? I’m interested to hear your thoughts.

I'd point out how you mis-represent the paper testing this scenario. Misrepresent by using the term "slightly more porous" to describe a 17% reduction of skeletal density with PO4 level at 0.5 ppm, which is actually significant, & a term not used in the paper.
And also mis-represent in suggesting here that P at a level of .5 ppm is beneficial.

Lets look at the abstract of the paper & what it says -

Effects of phosphate on growth and skeletal density in the scleractinian coral Acropora muricata: A controlled experimental approach

from the Abstract

Phosphate contamination can negatively affect corals, modifying growth rates, skeletal density, reproduction, mortality, and zooxanthellae.

We determined the effects of elevated phosphate on coral growth and density - of Acropora muricata - exposed to phosphate levels of 0.09, 0.20, and 0.50 ppm−1 for four months.

Total skeletal length, living tissue length, weight, branch production, and polyp extension were measured.
Linear extension and tissue growth increased under all conditions.

Growth rates were highest at a phosphate concentration of 0.50 ppm.
but
Density decreased through time, and was significantly lowest in the high phosphate treatment.

Skeletal density reduction may be due to phosphate binding at the calcifying surface and the creation of a porous and structurally weaker calcium carbonate/calcium phosphate skeleton.

Increased phosphate concentrations, often characteristic of eutrophic conditions, caused increased coral growth but also a more brittle skeleton.

The latter is likely more susceptible to breakage and damage from other destructive forces (e.g., bioerosion) and makes increased coral growth a poor indicator of reef health.

 

[Scrubber_steve]

I have the links for the research posted on page 1 or 2.
There is a lot more to phosphates than is assumed under the current common narratives related to phosphates on the forum. Some can mock me for posting the research but I hope a few take interest to it and maybe do some personal exploring.

This paper you linked is all to do with NO3 & PO4 take up by coral, in aquariums, under thermal stress

Limited phosphorus availability is the Achilles heel of tropical reef corals in a warming ocean

Basic Test parameters -

Uptake of inorganic nutrients at 25 °C (noted as “normal conditions”)
and 30 °C (noted as thermal stress conditions.)

Corals were exposed to -

1) Natural seawater, called control conditions, with low nutrient levels .0095 ppm PO4 & 0.031ppm No3

2) Phosphorus enriched conditions, 0.19 ppm PO4 & 0.031ppm NO3

From the Abstract:
We therefore assessed the uptake rates of nitrogen and phosphate by five coral species maintained under normal and thermal stress conditions.

Our results showed that nitrogen acquisition rates were significantly reduced during thermal stress, while phosphorus uptake rates were significantly increased in most species, suggesting a key role of this nutrient.

Discussion

Our analysis of the N and P uptake rates of four scleractinian and one soft tropical coral species shows that coral holobionts regulate the uptake of nutrients and points to higher P uptake rates under thermal stress.

All together, these observations strongly suggest that phosphorus is an essential nutrient for the symbiosis during stress events.

Conversely, nitrogen uptake rates significantly decreased under thermal stress, either due to coral bleaching and/or to avoid excess nitrogen in the coral tissue.

Our results highlight the importance of nitrogen and phosphorus availability in the coral response to thermal stress.

increased phosphate uptake seems to be a general response of corals to thermal stress, independently of the clade genotype or on the polyp activity.

Under control conditions, P and N uptake rates normalized to symbiont cell or holobiont biomass, as well as the ratios of N/P uptake, presented a threefold variation among the coral species tested, potentially reflecting different nutritional requirements and ecological trade-offs in the allocation of nitrogen and phosphorus amongst macromolecules associated with diverse functions.

 

[jda]

It is unfortunate that this link and paper has disappeared and moved, but it was very good, peer-reviewed study that had been supported many times.

From Dr. Holmes-Farley's Phosphate Paper. Most would say that he is a smart guy that understands the studies and also a reef tank in action:

Unfortunately, it is often present in excess in reef aquaria, and that excess has the potential to cause at least two substantial problems for reefkeepers. The first is that phosphate is often a limiting nutrient for algae growth, so when elevated it can permit excessive growth of undesirable algae. The second is that it can directly inhibit calcification by corals and coralline algae. Because most reefkeepers don't want either of these things to happen, they strive to keep phosphorus levels under control

 

[jda]

Here is more from Dr. Holmes-Farley. All of this is in his article, here:

http://reefkeeping.com/issues/2006-09/rhf/index.php#5

One important issue relating to elevated phosphate in reef aquaria has to do with the inhibition of calcification by phosphate and phosphate-containing organics. Phosphate is known to inhibit the precipitation of calcium carbonate from seawater.2-4 The presence of phosphate in the water also decreases calcification in corals, such as Pocillopora damicornis5 and entire patch reefs.6 This inhibition is likely related to the presence of phosphate in the extracytoplasmic calcifying fluid (ECF), where calcification takes place in corals7, and on the growing crystal's surface. Exactly how the phosphate gets into the ECF isn't well understood.

Figure 3. The chemical structure of the organophosphate "etidronate," shown in a fully protonated form.​

This inhibition of calcification takes place at concentrations frequently attained in reef aquaria, and may begin at levels below those detectable by hobby test kits. For example, one research group found that long-term enrichment of phosphate (0.19 ppm; maintained for three hours per day) on a natural patch reef on the Great Barrier Reef inhibited overall coral calcification by 43%.6 A second team found effects in several Acropora species at similar concentrations.8

Organic phosphate and phosphonate inhibitors of calcification have also been studied and probably work by a similar mechanism. Etidronate, a bisphosphonate that is used to treat osteoporosis (Figure 3), caused a 36% inhibition of calcification in Stylophora pistillata at 2 ppm, and stopped it completely (99%) at 100 ppm, while photosynthesis was not impacted at these, and higher, concentrations (indicating it is not a general toxin).9

 

[living_tribunal]

Here is more from Dr. Holmes-Farley. All of this is in his article, here:

http://reefkeeping.com/issues/2006-09/rhf/index.php#5

I looked at the studies Randy referenced in his paper and the results were consistent with what I’ve said all along.

The results from their high P scenario “Nitrogen additions stunted coral growth, and phosphorus additions had a variable effect. Coral calcification rate and linear extension increased in the presence of added phosphorus but skeletal density was reduced, making corals more susceptible to breakage.”.

Calcification itself was not inhibited but the skeleton was more porous, in line what what I’ve mentioned above. Overall calcification is higher but skeletons can be up to 17% more porous. This is arguably an issue in wild reefs but not in our tanks.

ENCORE: The Effect of Nutrient Enrichment on Coral Reefs. Synthesis of Results and Conclusions

Coral reef degradation resulting from nutrient enrichment of coastal waters is of increasing global concern. Although effects of nutrients on coral re…

www.sciencedirect.com

 

[living_tribunal]

I also find it interesting that you insult research and science insistently claiming “studies do not help anyone in this hobby” and then go and cite a study yourself.

Are you going to rebuke a scientific study someone you referenced references himself? Or are you going to just cherry pick specific points and take them out of context.

 

[jda]

Neither. I am going to trust somebody who both is a hobbyist and understands the studies. True, this is a rare cross section. I appreciate Lasse's viewpoint on most things too since he bridges both at most times. I have changed my viewpoint on some spectrum requirements based on his stuff (green, mostly).

I mostly have trouble with the people on this board using the studies in their posts. Most of which are unqualified for most thing. My links are to a smart guy's interpretation of the study, not my own interpretation... I am not a smart guy, but perhaps smart enough to know that I am not.

I do not have a ton of issues with most of the studies themselves. I do have issues with some studies when applying them to the hobby. For example, I don't care for any of Riddle's studies on Porites which is an incredibly easy coral to keep and the conclusions are meaningless to me since many have grown porites under incandescent lights with GE 100w... so what difference does it make when these things will grow anywhere - he has acknowledged and we laugh. I laugh at any study by a manufacturer or company owned by a manufacturer (CoraLab, for example).

I have also been around long enough to have seen Dr. Ron, Moe, Veron, Fenner, et al. and remember their help with research and the outcomes. I do not like the insinuation that somehow chemistry or coral biology has changed in 20 years.

Surely you can see the difference. If not, then we might not be on the same level.

I will not even bring up one of my main points that you probably do not have enough actual experience to see this for yourself. If you are still reefing in a decade or two, at least have the guts to find me and say that I was right all along with faster growth and with both stony/true coral and also coralline with P levels near NSW. This means that you would have to had ample time and experience with both, which many of the old-timers have since we used to have no GFO or LC to help us with our phosphates, which were OK, but not low.

Here is my main point... the vast majority of hobbyists would be much better served to pay attention to an opinion of a study like Dr. Holmes-Farley than just some dude on a message board... which is why I offer my own experiences and not my opinions of studies.

 

[RevMH]

Neither. I am going to trust somebody who both is a hobbyist and understands the studies. True, this is a rare cross section. I appreciate Lasse's viewpoint on most things too since he bridges both at most times. I have changed my viewpoint on some spectrum requirements based on his stuff (green, mostly).

I mostly have trouble with the people on this board using the studies in their posts. Most of which are unqualified for most thing. My links are to a smart guy's interpretation of the study, not my own interpretation... I am not a smart guy, but perhaps smart enough to know that I am not.

I do not have a ton of issues with most of the studies themselves. I do have issues with some studies when applying them to the hobby. For example, I don't care for any of Riddle's studies on Porites which is an incredibly easy coral to keep and the conclusions are meaningless to me since many have grown porites under incandescent lights with GE 100w... so what difference does it make when these things will grow anywhere - he has acknowledged and we laugh. I laugh at any study by a manufacturer or company owned by a manufacturer (CoraLab, for example).

I have also been around long enough to have seen Dr. Ron, Moe, Veron, Fenner, et al. and remember their help with research and the outcomes. I do not like the insinuation that somehow chemistry or coral biology has changed in 20 years.

Surely you can see the difference. If not, then we might not be on the same level.

I will not even bring up one of my main points that you probably do not have enough actual experience to see this for yourself. If you are still reefing in a decade or two, at least have the guts to find me and say that I was right all along with faster growth and with both stony/true coral and also coralline with P levels near NSW. This means that you would have to had ample time and experience with both, which many of the old-timers have since we used to have no GFO or LC to help us with our phosphates, which were OK, but not low.

Here is my main point... the vast majority of hobbyists would be much better served to pay attention to an opinion of a study like Dr. Holmes-Farley than just some dude on a message board... which is why I offer my own experiences and not my opinions of studies.

I don't always see eye to eye with your posts, we just go about thing differently, which is entirely fine, of course. I do very much appreciate your opinions and experiences.

I'm fairly sure this is the first time I've responded to anything you've posted. But man, this was well said. Hats off.

 

[Stigigemla]

In our home reefs there are a bit different views of how corals grow.
@Hanswerner and others have shown how coral sceleton growth is affected by lack of nickel and zink. These elements affect how brittle or dense a coral sceleton will be and the length between branching.
Circulation does affect this too.
In the last few years we have noticed that a slight pH increase from CO2 scrubbers will make the corals more dense.
I have customers that has birdsnest corals that halfed their branch length from the moment the CO2 scrubber was installed.