Randy's thoughts on trace elements

[michealprater]

Thank you to all that have contributed to this thread. I find the chemistry behind all things reef related fascinating. Sometimes it goes over my head, but by reading the discussions, I start to understand. To me this is a very fun part of the hobby. I greatly look forward to Randy's list of elements and their importance in the reef aquarium. I suspect there will be a list of some that are very important, and a list of some that really wont have much impact at all. Thank you again!

 

[Dorsetsteve]

This may be true but it most likely has nothing to do with nutrients. What nitrate concentrations are we talking about?

Nitrate is an oxidant that may prevent the dissolution of iron and manganese precipitated in the substrate (usually coral sand). The observation would suggest that one of both may have adverse effects in reef tanks, at least at elevated concentrations. In my experience iron is the suspect. Maybe it is not iron directly but an indirect, secondary effect, releasing something bound to the precipitated iron.

Detectable vs undetectable with the Salifert Nitrate test kit on low resolution, so at least 0.25ppm as per the result of the test.

The Bacto Balance and the All for Reef I was using do both supplement iron, I don’t recall if it does Manganese as well but both were available as per ICP results. I run bare bottom for reference.

I can’t present you with hard data or evidence only experience as a hobbyist and that is to maintain at least a testable level of Nitrate appears to have positive impacts on coral health with the converse being equally true. In terms of algae growth, particularly film algaes on the glass, this seems to be a mystery to me as to why or how quickly it grows.

 

[Miami Reef]

@Hans-Werner

You may have missed my questions here

Randy's thoughts on trace elements

Yes, at the same concentrations and in the same water corals may be phosphate limited while algae may be nitrogen limited. It is due to different demand and different uptake systems. How would a reef keeper use this idea to successfully reduce pest algae in a home mixed reef?

www.reef2reef.com

Thanks

I kept my phosphate at 0ppb with GFO and nitrate clear with salifert (vodka), and I had no trouble growing hair algae (derbasia).

The hair algae ONLY went away when I added a desjardini tang. No other herbivore (naso, orange shoulder, Mexican turbos, urchins) consumed it.

I fed my tank with frozen food about once a day, but I kept my nutrients at 0. Even so, the hair algae thrived until I found the proper herbivore.

I hope this helps you.

Here‘s the before and after added the sailfin (desjardini)

The hair algae was growing in all areas around my rockwork. This was just one area.

Before:

After:

 

[Hans-Werner]

Detectable vs undetectable with the Salifert Nitrate test kit on low resolution, so at least 0.25ppm as per the result of the test.

0.25 ppm nitrate is at least not the nitrate levels of 2 to 20 ppm usually given in this forum as target concentrations for dosing nitrate.

Although first experiments of the phosphate needs of corals under controlled conditions were done about 25 years ago more extensive experiments with diverse species and varied nutrient concentrations under controlled conditions have only been done in recent years. The results are very interesting, like in this article from 2023, this article from 2023 and this article from 2022. Especially the inclusion of an Acropora is interesting because corals of this genus to me seem to behave a little bit different regarding phosphate with rather higher phosphate needs for good growth and coloration, especially under LED lighting.

The molar weights are: nitrate 62 g/mol; phosphate 95 g/mol. The nitrate and phosphate concentrations mentioned in these articles are: nitrate 4.5 µM = 279 µg/kg = 0.28 ppm; phosphate 0.6 µM = 56 µg/kg = 0.056 ppm for "optimal/high concentrations", and nitrate 12 µM = 744 µg/kg = 0.74 ppm and phosphate 3 µM = 285 µg/kg = 0.28 ppm as "nutrient-replete conditions".

So, maybe at your tank we are actually talking about nitrate as a nutrient, at concentrations above 1 ppm this is very unlikely.

 

[Randy Holmes-Farley]

So, maybe at your tank we are actually talking about nitrate as a nutrient, at concentrations above 1 ppm this is very unlikely.

I’m having a bit of difficulty in reconciling this statement with the observation that many folks see visible improvements in their corals when raising nitrate from undetectable to the 2-10 ppm nitrate range.

I do not recall ever seeing someone report that corals do more poorly when raising nitrate into the 2-10 ppm range.

My best interpretation is this:

In some aquaria, corals get enough N from ammonia or nitrate or organic sources even when nitrate is low.

Other aquaria, however, lack these in sufficient quantity that additional N is needed, and that N availability is ensured by having at least a few ppm of nitrate. It might also be supplied by amino acid dosing or ammonia dosing, but nitrate presence assures adequacy.

 

[Randy Holmes-Farley]

Nitrate is an oxidant that may prevent the dissolution of iron and manganese precipitated in the substrate (usually coral sand). The observation would suggest that one of both may have adverse effects in reef tanks, at least at elevated concentrations. In my experience iron is the suspect. Maybe it is not iron directly but an indirect, secondary effect, releasing something bound to the precipitated iron.

If there are any effects like this, I expect they have to be driven by organisms. Nitrate is very interactive in water at room temperature, and it would not likely oxidize trace elements directly.

 

[Lasse]

From second article - my bold. This is figures from existing reefs with good growth!!!!

Corals were kept in nutrient-replete conditions ([NO3] ≈ 12 µM, [PO4] ≈ 3 µM), simulating nutrient environments that have been previously described for reefs with increased coral growth rates

It means (converted from µM (M = mol/L)) 0.74 ppm NO3 and 0.28 ppm PO4. (slight lower figures because 1 L salt water at 35 psu have the density of 1.023 but never the less) This was the nutrients in the long term experiment that indicate that the coral animal is indeed a farmer - i.e. it is probably not that way (as many believe) that the coral animal provides the zooxanthellae with nutrients created as surplus from the host's metabolism and receives energy in the form of carbohydrates back. This surplus has been believed to come from the coral animals captured (by polyps) prey. Instead have this study indicate that nutrients in the water is taken up by the zooxanthellae resulting in surplus population of zooxanthellae that is consumed by the coral animal that can grow on this food. If this is the way it works (and the studies from real guano enriched reefs in this paper strengthen this) - it also means that all micronutrients and trace elements that both the zooxanthellae and the coral animal need will be uptaken from the water column because the predation pathway of this compounds does not exist either. I do not say that the SPS corals animals polyps does not capture any prey at all - but I think they are mostly evolutionary remnants from the time before coral animals learned to use and grow zooxanthellae and which have remained because today they fulfill completely different needs - one of which - IMO - is to increase the surface area for diffusion of oxygen production during photosynthesis.

Another interesting conclusion - IMO - that can be drawn from this aquarium experiment is that zooxanthellae in these corals can use NO3 as a nitrogen source. This is due to the fact that no ammonium source is included in the experiment (more than the coral's own excretion)

An interesting observation I have made after having corals both with and without zooxanthellae is that those without are expanded by "food" availability in the water column (mostly during the dark hours) while photosynthesizing corals with small polyps often expand their polyps when it is at its brightest light - regardless of it is "food" in the water or not. I do not say that SPS polyp do not are able to catch prey but I believe that is not the the main purpose.

But 0.74 mg/L NO3 and 0.28 ppm PO4 in the water column will not limit any algae growth at all. And the atomic N/P ratio is 4/1 if I haven´t understand it totally wrong ! And this is from natural reefs!

Sincerely Lasse

 

[Troylee]

has anyone noticed algae grows faster on new/dry rock as opposed to established/ coralline rock?
…yes nutrient limitation is key but also is habitat denial/ displacement …
..it’s harder for algae to grow/ attach if something is already there

And in that sense I’ve proven to myself over and over with my current display that mixing up some calcium carbonate aka diy coral snow with bacteria and dosing the tank twice a week I’ve avoided all algae every time with brand new dry rock! The calcium carbonate distributes the bacteria and coats the rock with good bacteria and stops nuisance algae from ever getting a foot hold of the rock and corraline takes over in a couple weeks and I have a purple rock in 6-8 weeks that’s spic and span clean.

 

[Thales]

I'll try this again and then let the continued silence be the answer. Maybe Hans has me on ignore.

@Hans-Werner
"

Corals will grow on the phosphate and trace elements and will outcomplete green algae at nitrogen.

Do you have a example of this actually happening - corals being fed and given trace elements while algae diminishes? What levels or N and P, what levels or what trace elements? No herbivores?
I understand that these kinds of statements make sense hypothetically, but have yet to see any examples of this kind of success in reef tanks."






I think all too often one bit of info is taken from a paper and then unsupportedly generalized to support an idea and action that reef keepers are then encouraged to follow. I think this practice helps sell stuff that seems like easy/simple answers to reef issues, but also sets people up for frustration and dissapointment.
There is a huge difference betweem 'will' statments and 'maybe' statements.

 

[Hans-Werner]

I'll try this again and then let the continued silence be the answer. Maybe Hans has me on ignore.

@Hans-Werner
"

Do you have a example of this actually happening - corals being fed and given trace elements while algae diminishes? What levels or N and P, what levels or what trace elements? No herbivores?
I understand that these kinds of statements make sense hypothetically, but have yet to see any examples of this kind of success in reef tanks."






I think all too often one bit of info is taken from a paper and then unsupportedly generalized to support an idea and action that reef keepers are then encouraged to follow. I think this practice helps sell stuff that seems like easy/simple answers to reef issues, but also sets people up for frustration and dissapointment.
There is a huge difference betweem 'will' statments and 'maybe' statements.

You are not on "ignore" by me. In most of our tanks we have little to no green algae (sometimes some bubble algae, especially when there are fresh substrates like fresh coral sand or fresh rock). What are the exact numbers? I don't know the exact numbers at the moment because I decided to do quite free experimentation without numbers and check when I have a significant new knowledge.

When I checked numbers last time phosphate was around 0.2 ppm, nitrate low but detectable with our Tropic Marin Pro Test, maybe also 0.2 ppm, iron sometimes not found, sometimes 3 ppb, Mn similar, Ni 1 ppb, Cu and Zn usually below detection limit, iodine nearly 100 ppb.

I am sorry but at the moment I am a good example for "not chasing numbers".

 

[Thales]

You are not on "ignore" by me. In most of our tanks we have little to no green algae (sometimes some bubble algae, especially when there are fresh substrates like fresh coral sand or fresh rock). What are the exact numbers? I don't know the exact numbers at the moment because I decided to do quite free experimentation without numbers and check when I have a significant new knowledge.

When I checked numbers last time phosphate was around 0.2 ppm, nitrate low but detectable with our Tropic Marin Pro Test, maybe also 0.2 ppm, iron sometimes not found, sometimes 3 ppb, Mn similar, Ni 1 ppb, Cu and Zn usually below detection limit, iodine nearly 100 ppb.

I am sorry but at the moment I am a good example for "not chasing numbers".

Thanks Hans,

I am looking to see if there is any support for this statement and not seeing any -

Corals will grow on the phosphate and trace elements and will outcomplete green algae at nitrogen.

 

[jda]

I’m having a bit of difficulty in reconciling this statement with the observation that many folks see visible improvements in their corals when raising nitrate from undetectable to the 2-10 ppm nitrate range.

I do not recall ever seeing someone report that corals do more poorly when raising nitrate into the 2-10 ppm range.

My best interpretation is this:

In some aquaria, corals get enough N from ammonia or nitrate or organic sources even when nitrate is low.

Other aquaria, however, lack these in sufficient quantity that additional N is needed, and that N availability is ensured by having at least a few ppm of nitrate. It might also be supplied by amino acid dosing or ammonia dosing, but nitrate presence assures adequacy.

Don't discount that the nh4 and no2 were also likely more abundant as the no3 rose in the tank. no3 gets the credit since there is a test kit for it. Heavy in, medium/low out.

Obviously I don't know all tanks, but the few that I have pretty good knowledge of still had the same results if they upped export of the no3 and kept doing whatever they did to raise the no3 in the first place. These turned into heavy in, heavy out.

What I cannot reconcile is that fishless coral QTs and tanks struggle with corals without fish even if they dose no3.

 

[jda]

Another interesting conclusion - IMO - that can be drawn from this aquarium experiment is that zooxanthellae in these corals can use NO3 as a nitrogen source. This is due to the fact that no ammonium source is included in the experiment (more than the coral's own excretion)

Sincerely Lasse

I read that study that you posted a few times. It seems very possible that they missed that the host converts the no3 to ammonium, like nearly every other study has concluded. I would love to see a second study that matches this one - have you seen one? This is the only study that I have ever seen that things that zoox can use no3 directly for nitrogen.

For now, this conclusions is an outlier to me, but I am interested to read more and am keeping an open mind.

Edit: I also read a study once that zoox could get N from n2. I have never seen that again, either. This is also an outlier to me.

 

[danimal1211]

“By contrast, coral hosts cannot directly assimilate nitrate (NO3) because the animal tissue lacks the required enzymes15,17. Therefore, NO3 uptake and assimilation proceeds exclusively through the symbionts18. The same applies to phosphorus in its dissolved inorganic form (PO4)11. The extent to which N and P acquisition by the symbionts contributes to host growth is unclear and knowledge of nutrient partitioning remains incomplete”

As far as examples of fishless reef systems, Brandon429’s Pico is almost 20years and Maritza I believe is 10. I don’t think these systems should be so easily dismissed.

 

[Lasse]

It seems very possible that they missed that the host converts the no3 to ammonium, like nearly every other study has concluded.

No they have not missed it - as @danimal1211 shows in the post above. It is one of their premises for their argument.

All organisms that use NO3 as Nitrogen sources need to convert it to NH4/NH3 either just outside the organism or just at the inside before further transport and/or assimilation into amino acids. Its a energy demanding process that include different enzymatic processes. This is more or less an axiom.

Why using NO3 in this experiment instead of NH4/NH3 directly?

Its because NO3 is the predominant inorganic N species in oceanic water (and in water above reefs).

And this is my hobbyhorse when it comes to inorganic nitrogen sources in aquariums - this experiment not only proves zooxanthellae can take up inorganic N directly from the water column - it also shows they have the systems to convert NO3 into NH4/NH3 - IMO. Not all microalgae have this ability which will favour zooxanthellae (and the corals) if NO3 is the predominant inorganic N species in our reefs too. NH4/NH3 can be uptaken easily by most bacteria, micro and macroalgae and it is also true for organic amino acids that have the same or better permeation and transport capacity as NH4/NH3.

By using a fast nitrification and let the NO3 be the predominant N source - we will favour those organisms which have these enzymatic abilities to turn NO3 into NH4/NH3

Sincerely Lasse

 

[Lasse]

I also read a study once that zoox could get N from n2

This seems unlikely for me. This demand - as far as I know - a anaerobic environment in the immediate vicinity of the zooxanthellae and considering the algae's oxygen production during photosynthesis, it is not reasonable as far as I know. However some cyanobacteria have solved that problem by incorporate cells with thick cell walls (heterocysts) there the fixation happens. Never heard that for zooxanthellae.

Sincerely Lasse

 

[jda]

All organisms that use NO3 as Nitrogen sources need to convert it to NH4/NH3 either just outside the organism or just at the inside before further transport and/or assimilation into amino acids. Its a energy demanding process that include different enzymatic processes. This is more or less an axiom.

We are on the same page. I thought that the article was saying that they could use no3 directly by somehow taking off an N in some magic/unknown process and not first converting to nh3/nh4. Thanks for the explanation.

There are plenty of studies that show that no3 in the water is fine when nh[3,4] is not present with conversion cost. I with that I knew the conversion cost - seems like 30-70% additional energy is what some guess, but who knows?

 

[jda]

I am still not sure how they concluded that the zoox did this and not the host. I know what they wrote, but the tissue does not have to contain enzymes for the process to happen inside of the symbiont where there are indeed enzymes of some sort and the host tissue contains the symbionts. For all that I know, the zoox can lack the ability, but provide the enzymes and the host still does the work. Confuses me on how they define the tissue. In any case, this study is in the memory bank in case others come along to support it.

In the end, no3 to nh3/nh4 conversion at cost still needs to happen, so that is enough for me.

Edit: it just seems weird to me that no other dinos can convert no3 into nh3/nh4, so the host has to do something... even if it just provides the space and proximity for this to happen. It does not seem like a dino can do this alone. ...to be continued, I guess.

 

[danimal1211]

There seems to be more info on that in the citations mentioned.

 

[GARRIGA]

The only exception to this is when I want to grow algae like chaeto - I can limit this growth without harming corals by not dosing iron. This does not work on turf algae, though.

That’s interesting. Have you however seen GHA behest from adding iron to promote chaeto?