Are Nitrates really that important? Or is PO4 king?

[buruskeee]

Carbon dosing reduces nitrate considerably and perhaps phosphate a small amount. It is not used to deliver phosphate unless you mean highly specialized organics containing phosphate, or mean the consumption of bacteria by corals.

Thank you for clarifying. This is what was being discussed on Lou’s discussion on BRS’s YouTube channel yesterday. It seems only the phosphate introduced these bacterias and not the nitrates the way they were discussing.

 

[Dburr1014]

It seems only the phosphate introduced these bacterias and not the nitrates the way they were discussing.

Can you clarify this statement? What do you mean by "phosphate introduced these bacteria and not the nitrate".

Phosphate didn't introduce anything.

 

[buruskeee]

Can you clarify this statement? What do you mean by "phosphate introduced these bacteria and not the nitrate".

Phosphate didn't introduce anything.

I’m no expert here, and only trying to translate what was being discussed.

From what I gathered, it seems the phosphate/phosphorus feeds the bacteria/organisms that the corals consume and so in a way it’s delivering it to the corals.

Maybe someone else can chime in and explain in more detail or correct what is happening, but this is how I comprehend it.

 

[Randy Holmes-Farley]

I’m no expert here, and only trying to translate what was being discussed.

From what I gathered, it seems the phosphate/phosphorus feeds the bacteria/organisms that the corals consume and so in a way it’s delivering it to the corals.

Maybe someone else can chime in and explain in more detail or correct what is happening, but this is how I comprehend it.

That is a hypothesis without evidence, IMO.

It is certainly true that corals can take up inorganic phosphate.

 

[Randy Holmes-Farley]

On the nitrate question, it is certainly clear that corals can thrive if they get adequate N from other sources, but since we cannot readily track if they are sufficient, having detectable nitrate ensures N is not deficient, even if the source is not the most preferred.

 

[Randy Holmes-Farley]

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2009.54.5.1627

Depletion experiments were used to assess the uptake rates of phosphate by the tropical coral Stylophora
pistillata and its symbiotic zooxanthellae under different conditions. Our results showed the presence of active
phosphate carriers both in the animal and the algal fractions, since uptake kinetics followed uniphasic saturation
curves in both compartments (Michaelis–Menten shape). Transporters in the animal and the algae presented
different affinities for phosphate, with higher half-saturation

 

[bakbay]

Understand that having a detectable nitrate might be good for coral health. What about excessive nitrate? That is, my SPS & mixed tanks are running at 100+ NO3 and 0.20, 0.18 PO4; respectively. Should I stop testing & trying to reduce NO3 and just keep PO4 at bay?

 

[Randy Holmes-Farley]

There’s mixed data on the negative effects of elevated phosphate and nitrate, and at what level they may kick in. I dont think we have a good general answer at the moment, and it may depend on factors we understand (different organisms may respond differently) and on some we do not (such as levels of some other factors).

 

[rhitee93]

That is a hypothesis without evidence, IMO.

It is certainly true that corals can take up inorganic phosphate.

I'd love to hear more about your opinion on this.

The claim Lou presented in the video is that while corals can pull phosphorous out of solution in the water column, it is more efficient for them to consume it from particulate sources. (I'm paraphrasing this a bit based on my understanding) He then went on to explain that the true value of carbon dosing is in growing the bacteria that feed polyps, and that the fact this consumes/reduces phosphate levels is really just a bonus.

Seems logical as it was presented, but I have just enough chemistry knowledge to detect when I am being asked to trust a hypothesis, and not enough to actually judge the merits of the hypothesis for myself.

 

[Dburr1014]

On the nitrate question, it is certainly clear that corals can thrive if they get adequate N from other sources, but since we cannot readily track if they are sufficient, having detectable nitrate ensures N is not deficient, even if the source is not the most preferred.

Is this also a hypothesis or do you have any evidence on this? It seems you have to track ammonium/urea also to prove/disprove this Theory.

 

[Randy Holmes-Farley]

I do agree that bacteria feeding filter feeders is a nice benefit of organic carbon dosing and may be a reason to do it even if nitrate is fine.

I don’t even know what is meant by “efficiency” of P acquisition, but I expect that particulate organics including microorganisms (and maybe dissolved organics) is why corals can thrive in the ocean where phosphate is low while they often struggle to do so in a reef tank.

That said, I’ve not seen any evidence that there is any problem when corals seemingly get significant P from inorganic phosphate.

 

[Randy Holmes-Farley]

Is this also a hypothesis or do you have any evidence on this? It seems you have to track ammonium/urea also to prove/disprove this Theory.

The ocean is the evidence. Nitrate can be very low and yet corals get adequate N. It may be any or all of ammonia, urea, and organics containing N.

 

[Dburr1014]

The ocean is the evidence. Nitrate can be very low and yet corals get adequate N. It may be any or all of ammonia, urea, and organics containing N.

Yes, but, you have schools if fishes swimming all around pooping and secreting urea over everything.

So as I said, it would be difficult at best to prove coral get enough by nitrate alone.
Would you agree?

 

[danimal1211]

Yes, but, you have schools if fishes swimming all around pooping and secreting urea over everything.

So as I said, it would be difficult at best to prove coral get enough by nitrate alone.
Would you agree?

Reef-building corals farm and feed on their photosynthetic symbionts - Nature

Long-term experiments show that corals acquire dissolved inorganic nitrogen and phosphorus by feeding on symbiont cells, which provide essential nutrients enabling their success in nutrient-poor waters.

www.nature.com

 

[Lavey29]

As my dad would say "The proof is in da puddin". The ULNS fad went out years back.

 

[bakbay]

As my dad would say "The proof is in da puddin". The ULNS fad went out years back.

I spent way too much money & killed so many corals (now called "animals") many years ago trying to get to zero or undetectable N & P! As long as my corals are healthy and no crazy cyanos/dinos, I'm good.

 

[Randy Holmes-Farley]

Yes, but, you have schools if fishes swimming all around pooping and secreting urea over everything.

So as I said, it would be difficult at best to prove coral get enough by nitrate alone.
Would you agree?

If you are talking about the ocean, sure. There’s no reason to think they do get a lot of N from nitrate most of the time.

 

[buruskeee]

I spent way too much money & killed so many corals (now called "animals") many years ago trying to get to zero or undetectable N & P! As long as my corals are healthy and no crazy cyanos/dinos, I'm good.

I mostly agree with the “don’t chase numbers” crowd when it comes to nutrients, but I think the huge caveat To that is the tank (like yours) is already established and stabilized at an equilibrium.

For new tanks, IMO, targeting a baseline range of nutrients is very important to avoiding dinos/cyano and maintaining a healthy bacteria/biome population. What numbers to target is the question and what I’m trying g to get to the bottom to. It seems PO4 between 0.05 and 0.15 is becoming a widely accepted range these days, but NO3 is what’s completely confusing as there’s no real merit behind the range other than new school of thought of keeping it detectable as a “backup plan” for coral nutrition when ammonia levels become depleted.

It seems barely detectable NO3 all the way up to past 50ppm doesn’t really make a substantiated difference as long as PO4 levels are maintained.

 

[Lavey29]

I mostly agree with the “don’t chase numbers” crowd when it comes to nutrients, but I think the huge caveat To that is the tank (like yours) is already established and stabilized at an equilibrium.

For new tanks, IMO, targeting a baseline range of nutrients is very important to avoiding dinos/cyano and maintaining a healthy bacteria/biome population. What numbers to target is the question and what I’m trying g to get to the bottom to. It seems PO4 between 0.05 and 0.15 is becoming a widely accepted range these days, but NO3 is what’s completely confusing as there’s no real merit behind the range other than new school of thought of keeping it detectable as a “backup plan” for coral nutrition when ammonia levels become depleted.

It seems barely detectable NO3 all the way up to past 50ppm doesn’t really make a substantiated difference as long as PO4 levels are maintained.

You are correct with your phosphate range but if you think bottomed out nitrates won't affect you corals then your wallet is in for a bumpy ride for sure.

 

[Formulator]

Strong flow and algae movement especially for the free floating typs that self shade, strong lighting and sufficient trace elements (like iron) are also important for macro algae growth

I have ridiculous growth in my fuge with minimal flow; not enough to move the chaeto at all. I have to remove a softball sized clump or more weekly. I attribute this mostly to lighting. I have a Tunze submersible fuge light under the chaeto and a hygger LED bar on top. My iron was a bit low on my last ICP-MS, but I do pay close attention to my trace using the reef moonshiners program.