Nitrates and phosphates - what does the latest science say?

[jda]

As is claimed P release will happen without any help and it may happen very quickly, this observation is important. I would like to know where this information comes from.

Dr. Holmes-Farley's article on Phosphate lays it out pretty well.
http://reefkeeping.com/issues/2006-09/rhf/index.php

I also did a a study on phosphate binding to aragonite... it can hold a lot, and release a lot. The first 5 pages are good and then then it goes in a different direction.
https://www.reef2reef.com/threads/phosphate-absorption-rates-in-aragonite.352405/

ARM and Reborn are natural ground up coral from the ocean. The ones from KZ, Aquamedic are man made.

 

[jda]

In a closed system nutrients may be depleted, the bio- system may be starved, chains broken.

This is not a huge risk for phosphate since the aragonite acts as a buffer. If the water level gets really low, then some will unbind from the aragonite to replace it. The only way that this does not work is if you are removing the phosphate with GFO or LC faster than it can unbind from the rock and sand. This is why the "low but not too low" crowd never have to worry about getting to absolute zero if they are not using chemicals and media - even if they don't fully understand why.

Nitrate can be a bit trickier, but you usually need some extra to "drive" the equilibrium with the bacteria. Again, nobody really gets to true zero without organic carbon dosing.

For day-to-day nutrients, light feeding the zoox and then the zoox providing sugars to the corals are what give them energy. I hope that this is not getting interrupted and this chain broken.

 

[jda]

Here is the phosphate quote that I was referncing earlier. It is on page 19 of the thread below, which started as a DSB thread and took a tangent into P for a while - the few pages before and few pages after lay out the premise a bit more that urine is where the lions-share of phosphate gets excreted and that any that is in feces will get consumed over and over until there is some left, but not a significant amount.

I take dead fish out of the tank. If you do not, perhaps that is why you need to vacuum the substrate.

I am, as it happens, an expert on phosphate metabolism. I've studied it for more than 20 years, and have invented products that sell more than a billion dollars worth each year correcting hyperphosphatemia in people.

There is a flow chart in this link which shows the relative excretion of phosphate in urine (which is almost totally inorganic phosphate) and in feces (which is a combination of organic and inorganic phosphate).

https://www.inkling.com/read/medical...sphate-balance

The inorganic phosphate in urine excretion dominates, even if you ignore all of the inorganic phosphate in the feces. Then you seem to assume that all of that feces ends up in the substrate, which is utterly untrue. Other macroscopic creatures eat it, sometimes over and over. I had a kole tang that loved to eat my yellow tangs feces as fast as it came out. That drops the original phosphate ending up in feces by another factor of, say, based on the data above, three. Each cycle drops it significantly.

At the end of the day, yes, there obviously is phosphate making it to the substrate (as I've agreed along), but it is not the dominant player in phosphate balance in a reef tank.

In response to the question that P can build up over time and cause problems from feces:

Those numbers are obviously made up, but the point is that I do not dismiss that it happens, I dismiss it as significant relative to direct excretion.

http://www.reefcentral.com/forums/showthread.php?t=2268433&page=19

 

[Nathan Milender]

Nice article, worth discussing. Thanks for putting the time into a video.

To really see the data I will have to get a copy of the article. I am slow, and I usually need to see all the side info for the graphs to really think about the data and make sense of it. Assuming the spreading lines are confidence intervals as they usually are, there did seem to be some serious overlap. I was not clear if the y axis on many of the graphs was PO4, NO3, or growth. Regardless, the Y axis was really tight numerically in most of the graphics which makes me wonder if the differences could arguably be statistically relevant while not being all that clinically relevant (at least to a guy with some animals at home in a box). I was also not clear about what the timeline was for growth measured or how the time interval was normalized over 52 studies to really make a comparison. Even if the conclusion was that the growth measurements were not clinically different, it still appears that the levels of increased Nitrate and phosphate are at least not detrimental (although possibly on the mound corals). This could be the take home for those of us spending a lot of time chasing numbers.

If we consider it at face value and think higher (not outrageous) phosphate and nitrate helps corals does it make sense? I think it does. Considering the revolution in lighting with the understanding of promoting zooxanthellae growth to obtain coral growth, it stands to reason that fertilizer would be as important as light to the growth of these animals. I have not read an explanation of whether the diffusion of nutrients across cells in corals is needed for the corals or the zooxanthellae. I certainly do not understand the biochemistry behind coral metabolism enough to know which part is metabolizing phosphate and nitrate but most animals do not seem to be able to metabolize either in this form as far as I know. Corals could be relying on their partnership to provide the carbon and the nitrogen and the zooxanthellae need the phospherous for their own metabolism. It would be similar to us using nitrogen and phosphate to grow corn, the corn turns it into starch and protein, and we eat it. The better the corn grows, the fatter we get.

Why then is fish fertilizer (poop) more effective than manual fertilizer (chemical)? This is interesting when considering food crops and the revolution of modern fertilizers. We seem to get faster growth and yield production with the inorganic fertilizer revolution. In recent times there has been a backlash from the organic producers citing better taste and variability of complex molecules when using more natural fertilizers. It could be the slower release from feces requiring breakdown causes less of a chemical burden on the coral, or the feces has compounds we do not measure that the coral needs. I suspect it's both and probably some other things I have not thought of.

Everything here is just musing. Consider it that way when you read it as I have verified none of it. Glad to hear my nutrients can run higher as that is how I do it anyway.

 

[Belgian Anthias]

So, I have a couple of critical thinking questions... Is bioavailable N & P somehow less available at low but detectable levels than it is at higher levels? Is the mere presence of inorganic N & P evidence of suitable levels to support the systems chemical and biological processes because otherwise wouldn't they have consumed/bound/oxidized beyond detection?

It depends of other parameters such as organic carbon availability and of other building materials.
Some organisms are more effective in using P and will have an advantage at a very low P availability but may be outcompeted at a high availability of P.( availability may be effected by the level as it is the speed by which it can be suplied) Others are very effective in using NH4-N , some will rule at low N availability but will be outcompeted at a high availability of N and C. Some can use NO3-N when NH4-N is not available, others can not. N , C:N and N:S ratio's play an important role in the bio-chemical processes, more as the level I would think. Processes as nitrification, denitrification, DNRA, photo autotrophic and heterotrophic assimilation are more influenced by the available ratio's as by the available level The nitrate level does not influence the N uptake much as long enough NH4-N is available . Most organisms prefer NH4-N as a nitrogen source.
The availability of usable N and P is also dependable of the bio-mineralization rate!
The mere presence of N&P can be caused due to insufficient availability of an other crucial building material or not enough light. Without looking at the source one may think about the reasons why both N&P are present at an elevated level instead of being used.
I think for managing a closed system the effects of maintained ratio's are more important than the effects of maintained levels. Also for coral growth as they seem to live in a by the corals self managed ecosystem.
Maintaining the levels high enough to support the daily needs while maintaining a normal C:N ratio is what I would do.

 

[Belgian Anthias]

This is not a huge risk for phosphate since the aragonite acts as a buffer. If the water level gets really low, then some will unbind from the aragonite to replace it. The only way that this does not work is if you are removing the phosphate with GFO or LC faster than it can unbind from the rock and sand. This is why the "low but not too low" crowd never have to worry about getting to absolute zero if they are not using chemicals and media - even if they don't fully understand why.

Nitrate can be a bit trickier, but you usually need some extra to "drive" the equilibrium with the bacteria. Again, nobody really gets to true zero without organic carbon dosing.

For day-to-day nutrients, light feeding the zoox and then the zoox providing sugars to the corals are what give them energy. I hope that this is not getting interrupted and this chain broken.

Can you explain how P will unbind from the aragonite if the level gets low? Is there a connection between the Phosphate level and the release of P by aragonite? Can you explain how or can you tell me where I can find information as a reference?

Only carbon dosing? It is easily done adding elemental sulphur , the use of BADES. Full control over the nitrogen cycle and the nitrate level of a mixed reef aquarium can easily be done through BADES. Nitrogen is removed from the system. Can support a high bio-load. Not suitable for LNS and VLNS.

 

[jda]

Aragonite has the same binding relationship with phosphate that GFO has. It binds to "equilibrium" in an exponential manner. If you raise the water concentration, then more will bind... lower it and some will unbind.

There are a few paragraphs on this in RHF's article on phosphate as well as a link to a paper in the reference section.

 

[tenurepro]

Glad this thread is getting a bit more attention I think biomass and algae grazers play an important role as suggested by many folks above. Also, while it is tempting to fall in the confirmation bias trap (eg. I do x, x works, therefore x is best and y is inferior), I think we should be receptive to what the latest research is saying (after we give it some critical thought of course)

I typically like to cruise the reef science literature and given some of the fun discussion we’ve been having, I am planing to do a few more vids on some of the most interesting it’s of literature that I come across.
Cheers!

 

[Belgian Anthias]

Aragonite has the same binding relationship with phosphate that GFO has. It binds to "equilibrium" in an exponential manner. If you raise the water concentration, then more will bind... lower it and some will unbind.

There are a few paragraphs on this in RHF's article on phosphate as well as a link to a paper in the reference section.

Phosphate may precipitate on calcium carbonate and also struvite may be formed, removing P , N and Mg which which may be released back when pH drops below 7.9 GFO does bind the phophate and will not release it again. GAC will bind organic P which may be released back in the beginning but it will store it by bacterial activities, the forming of polymers on the GAC surface.
Any way, leaking is not the same as dissolving by bacterial activity.

 

[jda]

That is not correct. Both aragonite, GFO and Aluminum Oxide bind with phosphate in a reversible fashion that will unbind if the ambient water concentration is less than when it bound. The only way to "lock it in" is to grow new crystalline structure over it. You do not need to dissolve aragonite to get the P to unbind... or use organics... but it can unbind also with either.

GFO can leak out all of the phosphate that it bound if you leave it on the tank after you do a water change. People have found this out the hard way.

Did you not read through the phosphate binding on aragonite thread that I posted?

 

[Belgian Anthias]

That is not correct. Both aragonite, GFO and Aluminum Oxide bind with phosphate in a reversible fashion that will unbind if the ambient water concentration is less than when it bound. The only way to "lock it in" is to grow new crystalline structure over it. You do not need to dissolve aragonite to get the P to unbind... or use organics... but it can unbind also with either.

GFO can leak out all of the phosphate that it bound if you leave it on the tank after you do a water change. People have found this out the hard way.

Did you not read through the phosphate binding on aragonite thread that I posted?

Why? Any particular brand? And no, I did not.

 

[Belgian Anthias]

Marubindi and Davis publish in 1996 there research and conclude that the availability of nitrate influences zooxathellaea and coral growth but reduces skeletogenesis. In 1999 Marubindi and Atkinson conclude that reduction of calcification from lowered pH and C03 was greater than reduction from nitrate additions. Calcification following the Mc Connaughey en Whelan hypothesis, influenced by photosynthesis, as explained by Delbeek and Sprung in 2005 , let them assume that a nitrate level of +- 10 ppm induces max growth. The colour is not one of the parameters! Schneider and Erez conclude in 2006 that CO3 is the dominant factor! As not much of research done on natural reefs is about the colour of corals, it may be concluded that P and N management for maintaining very low levels is far less important for corals as most reefers think.