I have read all of this a million times, but it still does not address the question. If po4 never hits zero, then how could they ever be growth limited?
Look at the corals in my build thread at 1-3 ppb of phosphate. Look at any ZeoVit tank. Does these look starved for anything?
Also, the po4 in cancun, hawaii and in the coral sea was about 1 ppb - tested myself. I have only ever seen recorded po4 above this in lagoons and tidal pools. Millero showed the average reef po4 at .005 ppm in 2000.
I have NEVER, and I mean NEVER tested tank po4 at zero and I run at 1-3 ppb. Not even a stray test with hannah. There is next to no chance that the tank inhabitants can use up po4 faster than aragonite can release it, IMO. Browse through the build thread and see corals grow to dinner plate in a year, or 18 months, throw away 5 gallons of chaeto ever
I agree that the upwell is high in phosphorous, like Veron said. This phosphorous is bound into zooplankton and not in the form of po4, if you continue to read the book. Somebody only took what he wrote at half-measure. Besides, the was talking about the GBR and not all reefs, which he makes clear, and mentions in other books.
Lastly, who do people constantly mention how a natural reefs have all kinds of nutrients being added and act like nothing is ever added to a reef tank? I would think that any natural reef would like 5x Ehiem auto feedings of NLS pellets, mysis, chunky meat mix from Brine Shrimp Direct, flake food, etc. It is not like people set up a reef tank, never add anything and let all of the stuff in there fight each amongst each other for the scraps.
EDIT: I just calculated this roughly, and my reef gets just under 5 lbs of NLS pellets and about kilos combined of Mysis, Caribbean Mix and Pacific Plankton a month. I think that the ocean would love to have this kind of import per 300ish gallons of natural reef. I still have 1-3 ppb of phosphate.
You have some pretty corals.
You asked a question and I gave you an answer but since you've "read it all before" why don't you accept the research?
Well, there's a lot of ways corals can be growth limited. Phosphorus deficiency is just one. I've posted this fig 4 (below) from this
paper many times showing how corals can use particulate orgainic phosphorus, dissolved organic phophorus and dissolved inorganic phosphorus (PO4). So it's obvious corals can be kept with very little PO4. But we can't test for particulate or dissolved organic phosphorus and we can't quantify what's being used by other organisms in a system. So you've no clue how close your corals are to experiencing a PO4 deficiency. Maybe you could go another 5 years, maybe 10 years, maybe issues crop up in year 4. You don't know. And one thing I've learned both from experience over 4 decades of keeping reefs and three decades of maintaining them profesionally and most importantly, the research papers I've read is we need to be looking at the species/genotype/variety level needs of our corals do adequetly determine what individual corals need. Like feeding, there's multiple papers showing not only species specifc needs but if particualte foods are feed specific amounts may be need and too much or too little might be worse than nothing at al. So until we have that data I think we need to heed Delbeek's warning about "walking a narrow tight rope" as well as Southampton's research giving us a threashold number to work with.
And yes, some I would consider some of your corals at least partially bleached.
FWIW you can't deterimine a healthy coral by coloration. A healthy coral can be colorful but bright colors can't be used as an indicator of health. Depending on species photobiology lack of coloring fluorescent and chromo pigments can mean a coral has the right amount of light and doesn't have to waste metabolic energy making fluorescent or chromoproteins to deal with less than ideal lighting prameters. (And I'me sure you'll think this is heresy also but fast growth can't be used as an indicatror of health either.) If you want to prove your coral have a healthy photobiology show their Fv/Fm ratio is a healthy ratio, their zooxanthellae reproduction is n the order of 100 days and they have healthy phospholipid levels and their microbiome in their mucus layer is largely autotrophic. Again, we really need long term genus/genotype and variety level data on husbandry needs.
I'm really confused who you're talking about when you're talking about Veron. What you're claiming is being said saying isn't in his book I quoted him from. He is clearly refering generally to all the corals in the indopacific and australian waters not just the GBR. And it is PO4 the corals are exposed to with upwelling. Certainly there is zoo and phyto plankton current bring into reefs AS Debeek points out but upwelling is bringing nurtrient rich waters from the deep that test as high as .3 mg/l.
Please explain how you one time tests discredit, outweigh or prove wrong peer reviewed papers done by research groups? I had a good friend that smoked 1-2 packs everyday until he died in his late 80s but that doesn't disprove any of the research showing smoking is bad for you. It just shows he was lucky.
Can you post a link to Mollero's paper you're refferencing? I've breifly looked at his paper
Adsorption and desorption of phosphate on calcite and aragonite in seawater but I don't see where he addresses the role of biofilms altering sorption processes or how it would overide
Kleypas' PO4 levels on reefs.
"Many experiments have been conducted with mineral surfaces that can sorb
dissolved ions and organic molecules. It is well known that data, gained with
those mineralogical clean surfaces, cannot be simply applied and compared to
natural conditions. Organic matter is masking the original mineral surfaces and
thus, these surfaces change their sorption behaviour drastically."
Fig 4 from this paper on
"Phoshorus metabolism in reef organisms with algal simbionts"
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