Optimal phosphate level? (Mixed Reef)

[living_tribunal]

their figures are in μM. the ratio is actually 141:1

high nitrogen/low phosphorus (HN/LP = ~ 38 μM NO3−/~0.18 μM PO4−; N : P ratio = 211:1)
That means
phosphate: 0.017 ppm
nitrate: 2.4 ppm

cheers

The values and ratios are in μM, never said they were anything else. The ratios were also given in the study.

 

[living_tribunal]

I'm not too sure its as simple as this. I get algae growth in my scrubber even when NO3 & PO4 are reading zero.

It could very well be that it’s consuming most all of the available N and P as soon as it hits the column.

 

[jda]

The algae can get all of the nitrogen that it needs from ammonia/ammonium. There can be enough phosphorous in the tank for life to build that is not testable on any kit that we have - it does not take much. ...remember that N and P are not "food" - they are building blocks of life and a surplus of any kind is still a surplus.

While it is true that algae (or anything, for that matter) cannot grow without nitrogen, it does not have to come from nitrate, and it most cases, it does not.

 

[Scrubber_steve]

It could very well be that it’s consuming most all of the available N and P as soon as it hits the column.

I was just contemplating the magic ratio?

glennf runs a NP ratio of 50:1 he targets NO3 @ 2ppm & PO4 @ 0.04ppm

glenn gets great growth & has no algae & does no water changes. How does your theory account for his success?

 

[jda]

Having algae in a tank is more of a product of lack of consumers than it is having building blocks in the water. Even at .1n and .005p in my tanks, I would have algae all over the place with no urchins or snails.

Having algae in a tank is an indicator of nothing, IMO.

 

[living_tribunal]

I was just contemplating the magic ratio?

glennf runs a NP ratio of 50:1 he targets NO3 @ 2ppm & PO4 @ 0.04ppm

glenn gets great growth & has no algae & does no water changes. How does your theory account for his success?

But it’s not a theory, lots of academic research is proving this right now. I’m sure that people can have success by other means but I’m going to take my chances with the academics studying the impact instead of anecdotal evidence on a forum.

Not hating but the articles above show the impact of high N/low P on a few types of coral. Not only that but they explain the science behind how and why this occurs.

Why would I ignore that?

 

[living_tribunal]

I was just contemplating the magic ratio?

glennf runs a NP ratio of 50:1 he targets NO3 @ 2ppm & PO4 @ 0.04ppm

glenn gets great growth & has no algae & does no water changes. How does your theory account for his success?

You also ignored the part where I explained algae growth requires both of those parameters. If the phosphate is at that low of a level, the new algae growth will not have enough phosphate to absorb.

If it’s between the two, I’d simply rather decrease nitrate and maintain elevated phosphates given the impact on coral skeletal and tissue growth.

 

[ReefGeezer]

I'm not too sure its as simple as this. I get algae growth in my scrubber even when NO3 & PO4 are reading zero.

I wish it were that simple. I think bioavailable nitrogen compounds exist in at least a transient form regardless of test results. Algae can compete for those compounds where conditions are otherwise right for it to grow. Things like available substrate, light, trace elements like iron, lack of grazers, and etc. will allow it to grow to some extent even when test kits say that there are 0 inorganic nitrates in the water column.

 

[jda]

What makes you think that more of a surplus of a building block is any better than less of a surplus? If the organism has enough to build new tissue, then what does more do? Get to the crux of this question and you will have gotten further than 95% of the people on this board who think that N and P are "food" and that more does more. ...like somehow even a very small surplus of nitrogen or phosphorous is growth limiting in any way to corals.

 

[Scrubber_steve]

But it’s not a theory, lots of academic research is proving this right now. I’m sure that people can have success by other means but I’m going to take my chances with the academics studying the impact instead of anecdotal evidence on a forum.

you're taking some info from some studies, forming a theory & then making statements such as - "Anything under 10-14x will be great. Over 20x is when you see less growth."

And glenns' success is not anecdotal. He's had this success constantly for years, with multiple systems, & so have others who use his system.

Here's glennf's 300 gallon system, which he maintains at a NP ratio of 50:1 - NO3 2ppm, PO4 0.04ppm.

 

[living_tribunal]

I wish it were that simple. I think bioavailable nitrogen compounds exist in at least a transient form regardless of test results. Algae can compete for those compounds where conditions are otherwise right for it to grow. Things like available substrate, light, trace elements like iron, lack of grazers, and etc. will allow it to grow to some extent even when test kits say that there are 0 inorganic nitrates in the water column.

Technically speaking, algae doesn’t require these two nutrients at all to exist. Most is autotrophic and can produce their own sugars via photosynthesis. What I’m referring to is the algae blooms we see when algae is supplied available nutrients. For algae to grow, it really needs both in tandem to create a wild bloom like we see here on the forums.

 

[living_tribunal]

you're taking some info from some studies, forming a theory & then making statements such as - "Anything under 10-14x will be great. Over 20x is when you see less growth."

And glenns' success is not anecdotal. He's had this success constantly for years, with multiple systems, & so have others who use his system.

Here's glennf's 300 gallon system, which he maintains at a NP ratio of 50:1 - NO3 2ppm, PO4 0.04ppm.

What I'm doing is taking the ratios from numerous studies where corals demonstrated the strongest growth and implementing them in my reef and suggesting them to OP who asked just for that.

Will corals grow over 20x? Absolutely. The higher your N/P goes the more stressed corals become. This is evidenced by the significant amount of science we are now researching on the subject.

We are also learning more about how these two parameters interact with both the coral and algal symbionts that inhabit them.

It's clear that an undersupply of phosphate causes a severe disturbance in the symbiosis between the two and results in loss of coral skeletal and tissue mass if high enough. It's also clear that corals tolerate higher phosphate levels than they do nitrate.

To summarize, corals tolerate an undersupply of nitrogen significantly better than they do an undersupply of phosphorous.

 

[living_tribunal]

What makes you think that more of a surplus of a building block is any better than less of a surplus? If the organism has enough to build new tissue, then what does more do? Get to the crux of this question and you will have gotten further than 95% of the people on this board who think that N and P are "food" and that more does more. ...like somehow even a very small surplus of nitrogen or phosphorous is growth limiting in any way to corals.

It's more so what occurs when the nitrate increases relative to phosphate. Higher N will result in proliferating algal populations which in turn results in undersupply of phosphate.

Also, there are increased cellular demands from accelerated cell proliferation rates which are not met equally with the phosphate.

It's about the tipping point where the nutrient consumption shifts from the zooxanthelle to macroalgal dominance.

 

[Scrubber_steve]

This is interesting

These data support the precept that availability of N limits the productivity of macroalgae in temperate siliciclastic waters but, conversely, suggest that availability of P, rather than N, may be of paramount importance in limiting primary production of macroalgae in carbonate-rich tropical waters.

Nutrient Availability to Marine Macroalgae in Siliciclastic versus Carbonate-Rich Coastal Waters on JSTOR

Abundant populations of frondose epilithic macroalgae from a variety of carbonate-rich tropical waters were significantly depleted in phosphorus relative to car...

www.jstor.org

 

[Scrubber_steve]

Will corals grow over 20x? Absolutely. The higher your N/P goes the more stressed corals become. This is evidenced by the significant amount of science we are now researching on the subject.

I would suggest that glenn's corals aren't stressed, & that poses questions on the validity of the research, specifically when attributed to corals kept / raised in aquariums.

To summarize, corals tolerate an undersupply of nitrogen significantly better than they do an undersupply of phosphorous.

that's a reasonable assumption, on its own.

 

[living_tribunal]

This is interesting

These data support the precept that availability of N limits the productivity of macroalgae in temperate siliciclastic waters but, conversely, suggest that availability of P, rather than N, may be of paramount importance in limiting primary production of macroalgae in carbonate-rich tropical waters.

Nutrient Availability to Marine Macroalgae in Siliciclastic versus Carbonate-Rich Coastal Waters on JSTOR

Abundant populations of frondose epilithic macroalgae from a variety of carbonate-rich tropical waters were significantly depleted in phosphorus relative to car...

www.jstor.org

Lapointe has been studying the subject for many decades. He released a paper this past year which was the culmination of his many studies on the subject.

Here he discusses the effect of N enrichment in the various reefs he has studied:

"The stress mechanism involves an increase in the DIN:SRP ratio in the water column of coral reefs, which leads to P starvation of the coral symbiosis (evidenced by the buildup of sulpholipids on the algal lipodome, Wiedenmann et al. 2013). Rossett et al. (2017) concluded that SRP can be critically limiting at concentrations < 0.18 µM, especially if algal tissue N / P ratios exceed 22:1. My research has shown SRP concentrations < 0.18 µM and algal tissue N / P ratios in the range of 33—72 for declining coral reefs at DBML (Lapointe 1997), the Florida Keys (Lapointe et al. 2019b), and the Belize Barrier Reef (Lapointe and Tewfik 2019), supporting a role of P starvation and metabolic stress for coral bleaching and diseases in the Caribbean region. This research highlights the important role of P to endosymbiont photosynthesis and the functioning of symbiotic corals (Ferrier—Pages et al. 2016).

Future research needs to address the growing effects of global N enrichment in altering the N / P stoichiometry on coral reefs, especially remote coral reefs. Research has shown that land— based N loading is a driver of regional algal blooms and coral reef decline in the Florida Keys (Lapointe and Clark 1992, Lapointe et al. 2019a) and the Great Barrier Reef (Bell 1992, D’Eath and Fabricius 2010), a process that involves phytoplankton blooms and turbidity that increase light attenuation (Yentsch et al. 2002). On remote coral reefs, atmospheric N deposition in optically clear waters can enhance macroalgal blooms, even in the absence of terrestrial runoff (Barile and Lapointe 2005, Chen et al. 2019). Consequently, such atmospheric N deposition could also be altering the DIN:SRP ratio on remote reefs, causing metabolic stress that makes corals more vulnerable to coral disease and bleaching (Wooldridge 2009, Lapointe et al. 2019a). In particular, measurement of seawater DIN:SRP ratios, as well as C:N : P ratios and alkaline phosphatase activity of macroalgae and endosymbiotic zooxanthellae would elucidate the degree of P stress and potential for increased bleaching and disease. "

https://aquila.usm.edu/cgi/viewcontent.cgi?article=1591&context=gcr

 

[living_tribunal]

It appears that his research has indicated N/P ratios higher than 22x were what tipped the dominance from corals to macroalgae in the various reefs he covered.

 

[Thaxxx]

All of these studies you mention...
These are on open water coral reefs throughout the world.
Can a closed system that we run be a total differant set of target numbers?

 

[Scrubber_steve]

It appears that his research has indicated N/P ratios higher than 22x were what tipped the dominance from corals to macroalgae in the various reefs he covered.

>>> Rossett et al. (2017) concluded that "SRP (inorganic phosphate PO4) can be critically limiting at concentrations < 0.18 µM, (0.017 ppm) especially if algal tissue N / P ratios exceed 22:1. <<<<

PO4 at 0.017 ppm isn't recommended in the hobby. I interpret that statement to suggest that problems caused by this too low PO4 level are detrimental, and a NP ratio reaching 22:1 exacerbates the low PO4 problem further.

However I don't interpret that statement to suggest that NO3 at 2ppm, & PO4 at 0.04, being a NP ratio of 50:1, will be detrimental to aquarium coral.

The main cause of dominance from corals to macroalgae is over fishing & depletion in algae grazing fish & invert

 

[living_tribunal]

>>> Rossett et al. (2017) concluded that "SRP (inorganic phosphate PO4) can be critically limiting at concentrations < 0.18 µM, (0.017 ppm) especially if algal tissue N / P ratios exceed 22:1. <<<<

PO4 at 0.017 ppm isn't recommended in the hobby. I interpret that statement to suggest that problems caused by this too low PO4 level are detrimental, and a NP ratio reaching 22:1 exacerbates the low PO4 problem further.

However I don't interpret that statement to suggest that NO3 at 2ppm, & PO4 at 0.04, being a NP ratio of 50:1, will be detrimental to aquarium coral.

The main cause of dominance from corals to macroalgae is over fishing & depletion in algae grazing fish & invert

Lapointe says clear as day that N enrichment is the main cause of phosphate starvation which is impacting these corals.

N enrichment aside, the OP asked for optimal phosphate levels. I clearly referenced the science behind increased phosphate levels and their growth.

Anyone can make most reasonable parameters work in their tank. We have control of the biodiversity in there and can provide ample time for things to adjust as well.

If we are to set a proxy for what we could expect dominance to shift from corals to macro algae, Lapointe’s 30 years of research provides a fantastic starting point of 22x. If we further want to increase coral growth and be on the safe side, the additional research I referenced would indicate even higher phosphate levels.

If you want to disprove their research then set up an experiment we can measure and repeat consistently as they have. Till then, I believe I have supplied more than ample evidence from those with more than enough experience to support what their studies claim.