Rock absorbing nutrients?

[Dan_P]

Okay, I think I understand, but maybe we had different goals.

Let's say you have a running tank without substrate and a known PO4 level. And you wanted to fill that tank with x kilograms of your substrate. Would you be able to predict the PO4 adsorption/binding based on that? Or, could you create a phosphate solution to soak the substrate in, so it would have a minimal effect on the PO4 levels of the tank?

That was my initial goal, but it turned out to be difficult to approximate especially when testing in very small Jars.
In the end, I didn't go the fancy "math/chemistry" way and instead opted for the "engineering" way by simply adding substrate in batches and countering the measured delta in phosphate levels each day by dosing It gets the job done, but is less elegant

I still dropped to undetectable levels a few times (and still occasionally do when adding more)... Some dinos appeared but dosing nutrients and getting all trace elements back into order according to an ICP-MS test fixed the issue quite fast... Oddly enough Strontium appeared to make the difference for the dinos in the end, but I think that was pure coincidence

Have you published any of those studies here on R2R yet? Would be an interesting read

Have not published details yet. Experiment still in progresss.

The small jar approach could have worked or you could have performed the batch treatment with PO4 outside the aquarium before adding it. That would have been done at a larger scale and with ample to test. Stirring the water would have required a small powerhead.

The appearance of dinoflagellates on newly added sand would not be surprising. Dinoflagellate growth on old surfaces after adding new sand would be interesting.

 

[Dan_P]

I think an iterative dose and measure approach would work best. It takes a lot, but one could also substantially overshoot and then be stuck over target.


It can keep on absorbing more and more if the amount in the water is sufficient. Then it could release that later when you try to keep it lower.

Agree ^^^ The maximum concentration can be at or slightly above the target.

A large volume of water to rock volume will ease the pain of frequently dosing phosphate. Observing whether there is progress in saturating the aragonite surface, sand or rock, can be done by measuring the phosphate concentration several times the first day to obtain a baseline adsorption rate. After a two or three phosphate doses, measure the rate again. You don’t need many points. Every six hours can be informative.

 

[EnterName]

Have not published details yet. Experiment still in progresss.

I will be patiently waiting

The small jar approach could have worked or you could have performed the batch treatment with PO4 outside the aquarium before adding it. That would have been done at a larger scale and with ample to test. Stirring the water would have required a small powerhead.

Yes, I just got tired of having buckets full of sand sitting around with nowhere to put them, so I decided to just go for it and hoped small batches wouldn't make a difference in a 171gal tank. Apparently I was wrong, but then again: I run my tank below 0.05ppm PO₄ so the buffer will be limited.

The appearance of dinoflagellates on newly added sand would not be surprising. Dinoflagellate growth on old surfaces after adding new sand would be interesting.

Interestingly the dinos (Ostreopsis spp.) appeared on the little bit of old sand from the previous system that I transferred to keep a little bit of the microfauna (not more than 250mL of sand). And obviously the glass of the new tank was covered as well. The rocks were only slightly affected (that was the point where I actually got nervous).

The dinos pretty much fully disappeared after bringing nutrients and trace elements back to normal. I only see a few Amphidinium spp. cells in some weird inactive state on the backwall (Second image, page 1, post #3 on my thread, they are basically circular instead of oval). The only active cells I see are present on some coral tissue that got hurt during the transfer.

It's really weird how my tank went from Prorocentrum spp., through Ostreopsis spp., to Amphidinium spp. over the years while never really struggling with actual outbreaks, and always side by side with a decent amount of diatoms because my silicate levels were always elevated.

 

[Dan_P]

I will be patiently waiting


Yes, I just got tired of having buckets full of sand sitting around with nowhere to put them, so I decided to just go for it and hoped small batches wouldn't make a difference in a 171gal tank. Apparently I was wrong, but then again: I run my tank below 0.05ppm PO₄ so the buffer will be limited.


Interestingly the dinos (Ostreopsis spp.) appeared on the little bit of old sand from the previous system that I transferred to keep a little bit of the microfauna (not more than 250mL of sand). And obviously the glass of the new tank was covered as well. The rocks were only slightly affected (that was the point where I actually got nervous).

The dinos pretty much fully disappeared after bringing nutrients and trace elements back to normal. I only see a few Amphidinium spp. cells in some weird inactive state on the backwall (Second image, page 1, post #3 on my thread, they are basically circular instead of oval). The only active cells I see are present on some coral tissue that got hurt during the transfer.

It's really weird how my tank went from Prorocentrum spp., through Ostreopsis spp., to Amphidinium spp. over the years while never really struggling with actual outbreaks, and always side by side with a decent amount of diatoms because my silicate levels were always elevated.

In my experimental aquaria and in past experiments, i have somehow managed to create pelagic Amphidinium blooms. EDIT: you could have a large pelagic dinoflagellate population and not notice it.

Your mention of inactive Amphidinium cells leads me to ask what causes the rapidly, flitting about Amphidinium cell to settle on a surface? I wasn’t going to call them inactive only because I think that I can see flagella movement. Also, I have seen the chubby round version though I don’t recall seeing a vacuole (?) in the dead center of the cell.

 

[EnterName]

I will be patiently waiting


Yes, I just got tired of having buckets full of sand sitting around with nowhere to put them, so I decided to just go for it and hoped small batches wouldn't make a difference in a 171gal tank. Apparently I was wrong, but then again: I run my tank below 0.05ppm PO₄ so the buffer will be limited.


Interestingly the dinos (Ostreopsis spp.) appeared on the little bit of old sand from the previous system that I transferred to keep a little bit of the microfauna (not more than 250mL of sand). And obviously the glass of the new tank was covered as well. The rocks were only slightly affected (that was the point where I actually got nervous).

The dinos pretty much fully disappeared after bringing nutrients and trace elements back to normal. I only see a few Amphidinium spp. cells in some weird inactive state on the backwall (Second image, page 1, post #3 on my thread, they are basically circular instead of oval). The only active cells I see are present on some coral tissue that got hurt during the transfer.

It's really weird how my tank went from Prorocentrum spp., through Ostreopsis spp., to Amphidinium spp. over the years while never really struggling with actual outbreaks, and always side by side with a decent amount of diatoms because my silicate levels were always elevated.

In my experimental aquaria and in past experiments, i have somehow managed to create pelagic Amphidinium blooms. EDIT: you could have a large pelagic dinoflagellate population and not notice it.

Your mention of inactive Amphidinium cells leads me to ask what causes the rapidly, flitting about Amphidinium cell to settle on a surface? I wasn’t going to call them inactive only because I think that I can see flagella movement. Also, I have seen the chubby round version though I don’t recall seeing a vacuole (?) in the dead center of the cell.

I frequently take samples with a plankton net 11μm, so I would have expected to notice pelagic cells, but it might still be possible.

I referred to the chubby circular ones as inactive where I never saw flagella or any movement at all. The "normal" cells are actively swimming and seem to use their flagella all the time. I have not looked into resting cysts of Amphidinium (if they have any) maybe that's when the central pyrenoid becomes so prominent just like we see in benthic Prorocentrum species like P. lima. But it's certainly interesting to have them settle into algae and biofilm on the back wall rather than substrate. It might indeed be not a typical benthic species. I'm currently gathered taxonomic data and keys of all sorts. I will look into Amphidinium but for most dinoflagellates you need electron microscopy to distinguish species.

 

[keagan]

It would be interesting to test saturation methods in identical buckets with the same amount of dry rock, salinity, source water, etc. Test slow dosing phosphate and ammonium chloride v a large amount infrequently v a biological source like a 20g cocktail shrimp. Do we reach equilibrium faster using any of the above?

 

[Randy Holmes-Farley Verified Community Expert]

It would be interesting to test saturation methods in identical buckets with the same amount of dry rock, salinity, source water, etc. Test slow dosing phosphate and ammonium chloride v a large amount infrequently v a biological source like a 20g cocktail shrimp. Do we reach equilibrium faster using any of the above?

What sort of equilibrium ae you referring to? You mean the phosphate/rock equilibrium?

Phosphate binding to calcium carbonate rock is controlled by the rock surface area, and unless organics or bacteria are blocking some of the surface area, the amount that binds is only a function of the equilibrium phosphate concentration in the water (higher means more binding). .

 

[keagan]

What sort of equilibrium ae you referring to? You mean the phosphate/rock equilibrium?

Phosphate binding to calcium carbonate rock is controlled by the rock surface area, and unless organics or bacteria are blocking some of the surface area, the amount that binds is only a function of the equilibrium phosphate concentration in the water (higher means more binding). .

Sorry that wasn't clear. Chemistry isn't my stronge suit, that is what I mean.

This is the way this layman was looking at it:
A phosphate dose → PO₄ spikes → rock adsorbs it → water returns toward 0ppm.
Another phosphate dose → same thing happens.

A decomposing shrimp → continuously generates PO₄ → rock keeps seeing phosphate.

Or the shrimp speeds biofilm development on the rock and blocks access points.

I don't really have a hypothesis I just think it would be interesting to observe if release pattern or source matters. From what you said though I'm assuming this is already well understood for those with a better grasp of the science .

 

[Randy Holmes-Farley Verified Community Expert]

OK, thanks for the clarification.

You volunteering to run an experiment? :)

Yes, phosphate absorption onto and into aragonite is well studied by both reefers and chemical oceanographers. It's an important process in coastal waters.

Here's a study Jonas Roman did:

@JonasRoman


https://www.reef2reef.com/threads/how-much-phosphate-can-a-phosphate-free-limestone-absorb.1140207/

and here's a typical oceanographer study:

https://www.aoml.noaa.gov/flbay/millero1.html

 

[keagan]

OK, thanks for the clarification.

You volunteering to run an experiment? :)

Yes, phosphate absorption onto and into aragonite is well studied by both reefers and chemical oceanographers. It's an important process in coastal waters.

Here's a study Jonas Roman did:

@JonasRoman


https://www.reef2reef.com/threads/how-much-phosphate-can-a-phosphate-free-limestone-absorb.1140207/

and here's a typical oceanographer study:

https://www.aoml.noaa.gov/flbay/millero1.html

If it's worth doing what I outlined above I've already been buying up dry rock for a new system so it would be really cheap to do. I would happily run the proposed experiment. However you have me wondering if anything of note could be observed, with a large body of literature already existing on the subject. Be blunt with me, I'm not going to be offended is it a waste of time? Also thanks for sharing your expertise :).

 

[Randy Holmes-Farley Verified Community Expert]

If it's worth doing what I outlined above I've already been buying up dry rock for a new system so it would be really cheap to do. I would happily run the proposed experiment. However you have me wondering if anything of note could be observed, with a large body of literature already existing on the subject. Be blunt with me, I'm not going to be offended is it a waste of time? Also thanks for sharing your expertise :).

What could be shown was if (and how much) the presence of bacteria on the rock impact phosphate absorption to rock. I would find that interesting, but I don't think it would change anyone's cycling plans.

 

[Dan_P]

I frequently take samples with a plankton net 11μm, so I would have expected to notice pelagic cells, but it might still be possible.

I referred to the chubby circular ones as inactive where I never saw flagella or any movement at all. The "normal" cells are actively swimming and seem to use their flagella all the time. I have not looked into resting cysts of Amphidinium (if they have any) maybe that's when the central pyrenoid becomes so prominent just like we see in benthic Prorocentrum species like P. lima. But it's certainly interesting to have them settle into algae and biofilm on the back wall rather than substrate. It might indeed be not a typical benthic species. I'm currently gathered taxonomic data and keys of all sorts. I will look into Amphidinium but for most dinoflagellates you need electron microscopy to distinguish species.

Good idea using the plankton net. Inhave to wonder if the bacteria blooms reported here are really dinoflagellate blooms. A microscope and plankton net would be all that’s needed to answer my question.

 

[Randy Holmes-Farley Verified Community Expert]

Back when I was having the supposed dino issues in my tank, if I looked at the water in the tank I could see a scintillation in the water that is not there now. I assumed it might be the phyto I was dosing, but I’m still using the same
Phyto at the same dose and do not see it. I now assume I was seeing pelagic dinos.

 

[JonasRoman]

Long story short, after some neglect my 14 gallon had a severe bubble algae outbreak and I decided to re-scape entirely with dry rock (Tropic Eden). This seemed to worsen my pre-existing dino issue (ostreopsis) so I decided to test more regularly. I quickly realized that both my nitrates and phosphates were at 0. Along with feeding, I have been dosing NeoNitro and NeoPhos daily for over a month now and it has been very difficult to raise these values. My nitrates seem so respond however it tends to drop around 1-2 ppm each day. It is very difficult to get my phosphates over 0, even dosing 10 ml which seems like a lot. My best guess is the rock is absorbing these nutrients, and I am looking for some guidance as it seems to be fueling the dinos (UV doesn't seem to be helping). I do about a 5% water change each week to get them off the sand bed. Thankfully the corals look great and are growing.

Many good answer already, but give my opinion on this: I have done some studies, published here, that naked limestone ca bind quite much po4, and there is 2 way of binding. We see this , maybe always, in new tank where dead rock is dominating the scape. After some time, maybe a few months, the rock stop absorb po4, and po4 rise in water finaly. AMO I would never dose po4, as its just consumed by rock at this moment, the coral will not get much of the dose (or the zooxanthelle which is he main target for inorganic P, Po4). But as you imply, dino loves it. You say UV doesnt help, my advice is to combine black out with UV, that have always been successfull in my cases, even with those dino that not so easy leave the sand bed or rocks. Because, if you do a total black out, the stubborn dinos will sooner or later leave rock and sand, and finaly the UV will kill it. Also make sure UV is strong enough and the pump that runs the UV is correct for that effect of the UV. In my 500 liters I used a 55W UV, equipped with a pump 2000l/h.(tropic marine semiprofessional UV).
After the black out of 3 das I continued with UV further a few days. Now also, the PO4 will raise, as Dino binds a lot of PO4. What is the hen and egg concerning po4 and dino?. I am not so sure low Po4 gives dino, but I for sure know that dino consumes po4, so zero po4 and dino is often 2 signs you see at same time.

Concerning preosak dead stone with PO4 before doing the scape. I would not do that (but do not say to others they shouldnt), because I do not see this as a huge problem. My initial phase with same scenario, low PO4 thanks to dead stone, was not really a problem as I fed the coral with organics some time, and had quite much fish so the system was not starving anyway from P. Also, if presoak the stone, you will maybe oversaturate, and it releases po4 to the water more than you want, an uncontrolled process.

Jonas

 

[sixty_reefer]

Ammonia is the preferred nitrogen source for corals, algae, and bacteria, as nitrate has to be converted back to ammonia first before these organisms can get to the precious nitrogen they actually want (there may be a few exceptions to this rule). This conversion requires energy and precious trace elements that can limit the actual nitrogen uptake.

Preferred under what conditions and by which organisms? “Corals, algae and bacteria” covers an enormous range of metabolisms. Surely the nitrogen source preference depends on the organism.

 

[Randy Holmes-Farley Verified Community Expert]

Preferred under what conditions and by which organisms? “Corals, algae and bacteria” covers an enormous range of metabolisms. Surely the nitrogen source preference depends on the organism.

It may, but I have not seen a study showing a marine organism preferring nitrate over ammonia. It would be unusual to prefer nitrate as organisms always convert it to ammonia to use and that takes energy.

 

[sixty_reefer]

It may, but I have not seen a study showing a marine organism preferring nitrate over ammonia. It would be unusual to prefer nitrate as organisms always convert it to ammonia to use and that takes energy.

For the great majority that may well be correct but not for all organisms. some organisms have been shown to prefer nitrate over ammonium and things like light, residual nutrient and iron availability can also influence which nitrogen source is favoured.

 

[EnterName]

Preferred under what conditions [...]?

Obviously there is a limit at which ammonia levels become too low to assimilate so that's a point where nitrate will become "preferred" (but only due to necessity). The exact level at which this happens depends on the organism, but in our tanks we have very high nutrient levels compared to the ocean, so I doubt we are capable of reaching said limits without huge effort.

[...] and by which organisms? “Corals, algae and bacteria” covers an enormous range of metabolisms. Surely the nitrogen source preference depends on the organism.

An apparently "obvious" exception would be denitrifying bacteria that have adapted to deal with nitrate, but they only matter if nitrate is present, so we don't have to worry about them.
Some bloom-forming dinoflagellates might be possible candidates as well, as they are found in nitrate-rich waters in the ocean and could have evolved uptake mechanisms to profit from nitrate before other organisms can take it up. I'm not sure if this applies to the benthic species we find in our tanks though.
There are also some diatoms that can store nitrate in vacuoles, but these are not really organisms we have to take care of in our tanks, as corals will starve long before diatoms will and I'm not sure the diatoms we find in our tanks have the described capability.
These are "skills" that depend on species and were evolved to deal with specific conditions, so it's the exception rather than the rule. (bio-energetic explanation follows down below)

So: Yes, if you consider these exceptions it depends on the organism, but these exceptions don't really matter for our reef tanks as far as I know.

Just from a bio-energetic standpoint it doesn't make sense to prefer nitrate because DNA doesn't contain nitrate, but nitrogen. So organisms have to reduce it sooner or later or they won't be able to use it for growth. This reduction requires enzymes/energy/time, so there is no benefit in using nitrate if the organism isn't trying to fit into some specific biological niche. Additionally ammonia is available before nitrate is, so why wait for nitrifying bacteria to oxidize ammonia? This would be a competitive disadvantage over organisms that use ammonia directly.

If you are interested in the topic there are a lot of scientific papers about it and the reasons behind it. In this short response I can only give a summarized and simplified explanation, so I can genuinely recommend going down the rabbit hole. It's a quite fascinating topic and helped me with the decision if nitrate or ammonia dosing was the better approach for my system. These 3 papers here are freely accessible and are a great introduction in the research, reasoning behind the preference, and a practical approach on how this was tested.

• Dortch 1990 (Widely-cited review confirming the ammonia/ammonium preference)
• Raven 1992 (This explains the bio-energetic standpoint very well)
• LeKieffre et al. 2020 (experimental proof using isotype-labeling for a few organisms)

 

[sixty_reefer]

Obviously there is a limit at which ammonia levels become too low to assimilate so that's a point where nitrate will become "preferred" (but only due to necessity). The exact level at which this happens depends on the organism, but in our tanks we have very high nutrient levels compared to the ocean, so I doubt we are capable of reaching said limits without huge effort.


An apparently "obvious" exception would be denitrifying bacteria that have adapted to deal with nitrate, but they only matter if nitrate is present, so we don't have to worry about them.
Some bloom-forming dinoflagellates might be possible candidates as well, as they are found in nitrate-rich waters in the ocean and could have evolved uptake mechanisms to profit from nitrate before other organisms can take it up. I'm not sure if this applies to the benthic species we find in our tanks though.
There are also some diatoms that can store nitrate in vacuoles, but these are not really organisms we have to take care of in our tanks, as corals will starve long before diatoms will and I'm not sure the diatoms we find in our tanks have the described capability.
These are "skills" that depend on species and were evolved to deal with specific conditions, so it's the exception rather than the rule. (bio-energetic explanation follows down below)

So: Yes, if you consider these exceptions it depends on the organism, but these exceptions don't really matter for our reef tanks as far as I know.

Just from a bio-energetic standpoint it doesn't make sense to prefer nitrate because DNA doesn't contain nitrate, but nitrogen. So organisms have to reduce it sooner or later or they won't be able to use it for growth. This reduction requires enzymes/energy/time, so there is no benefit in using nitrate if the organism isn't trying to fit into some specific biological niche. Additionally ammonia is available before nitrate is, so why wait for nitrifying bacteria to oxidize ammonia? This would be a competitive disadvantage over organisms that use ammonia directly.

If you are interested in the topic there are a lot of scientific papers about it and the reasons behind it. In this short response I can only give a summarized and simplified explanation, so I can genuinely recommend going down the rabbit hole. It's a quite fascinating topic and helped me with the decision if nitrate or ammonia dosing was the better approach for my system. These 3 papers here are freely accessible and are a great introduction in the research, reasoning behind the preference, and a practical approach on how this was tested.

• Dortch 1990 (Widely-cited review confirming the ammonia/ammonium preference)
• Raven 1992 (This explains the bio-energetic standpoint very well)
• LeKieffre et al. 2020 (experimental proof using isotype-labeling for a few organisms)

I’m not sure denitrifying bacteria would count as an exception here. They use nitrate mainly as an electron acceptor for respiration, which is a different process from preferring nitrate as a nitrogen source for assimilation. Maybe cyanobacteria would actually be a better example here.

 

[EnterName]

I’m not sure denitrifying bacteria would count as an exception here. They use nitrate mainly as an electron acceptor for respiration, which is a different process from preferring nitrate as a nitrogen source for assimilation. Maybe cyanobacteria would actually be a better example.

If you want to differentiate between uptake and other use, that's a whole different distinction. But, I think many denitrifying bacteria still prefer ammonia for nutritional uptake, so in that sense it further proves the rule. It doesn't change the original point you were asking about though:

Preferred under what conditions and by which organisms? “Corals, algae and bacteria” covers an enormous range of metabolisms. Surely the nitrogen source preference depends on the organism.

So I can only repeat myself and recommend looking at the bio-energetic reasoning, evolutionary standpoint, and also the research that has been done on the topic so far.
In the original response you were asking me about, I specifically mentioned that there are exceptions.