Sixty’s Understanding of Nutrient Ratios

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Interesting topic!

@Randy Holmes-Farley @Lasse Do we know the rate at which bacteria/corals consume NO3/PO4? It is to my understanding that the readings we get while testing are just residual unused nutrients. So does this mean that the corals have not taken up those nutrients yet, or is it that they have taken what they can and won't take the rest up and they need to be removed(water changes, carbon dosing, etc)?

If it means they won't take up the left over residual nutrients then it would make since to feed heavy while keeping NO3 and PO4 low.

I don’t think the rate is known as we don’t discuss it enough.
if it was discussed a certain C N P rate could be determined for optimal function of a system.
All we know is that they are being produced and utilised on a constant movement. Very similar to Ca dosing the only difference being we know how much Ca we adding to the system. So we know how much Ca the System is utilising by testing the residual unused Ca

I personally believe that we can interpret the residual unused nutrients to determine what’s limiting or in abundance in a system. Giving the end user enough information to adjust the C N P input of a system to reduce residual unused nutrients.
The same way we do for dkh Mg and Ca
 
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Lasse

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It is to my understanding that the readings we get while testing are just residual unused nutrients. So does this mean that the corals have not taken up those nutrients yet, or is it that they have taken what they can and won't take the rest up and they need to be removed(water changes, carbon dosing, etc)?

If it means they won't take up the left over residual nutrients then it would make since to feed heavy while keeping NO3 and PO4 low.
It means that the whole system is overloaded - both biological uptake and chemical bond PO4 - see this

Sincerely Lasse
 

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Redfield is relatively new to me and not being one to be exact on anything and preferring to take a more holistic view then knowing exact ratios might have started as a need but now based on actual application have some to the conclusion that it may not.

Been running an experiment with a 20H using a DIY undergravel plate that provides contact as it pulls water from the one end of the tank to the other under four inches of pumice coupled with about an inch of coral skeletons on top to assist with nitrification. Goal was to exhaust DO in order to allow denitrification to take place. This was working early on but since I don’t perform WCs or remove detritus other than what gets trapped in a small floss section surrounding GAC that builds up over time. Fact is used a Turkey baster to disturb the rocks and water became quickly cloudy to the point visibility was near zero confirming there’s detritus yet to be decomposed and can only assume there must be a large volume under the gravel plate.

What I’ve learned. Detritus takes longer to decompose then assumed or perhaps I’m not supplementing with enough heterotrophic bacteria. Something I have been doing periodically but not on a schedule. Mostly when nitrates start to climb. Use MB7. Nassarius snails added don’t seem to be feeding on it. Amphipods added don’t seem to be feeding on it. Thought was that as detritus decomposes it would naturally release carbon needed for denitrification. The latter part I’ve understood was needed before learning about Redfield and from back in the 80s when I first started studying denitrification knew that a source of food was required. At the time didn’t know it was carbon.

Besides the rate at which detritus decomposes, I’ve learned that ammonia and nitrites have not spiked. Early on in order to lower nitrates I added phosphates which was the catalyst as oddly my tank is phosphate deprived unless my nitrates rise. Haven’t figured that one out yet since I don’t run GFO and only time I’ve run PhosGuard was due to a high level of diatoms early on. Could have just let it run it’s coarse but I wanted to see how quickly that worked since I’m 50 plus years of keeping fish this was my first having it.

These days I’m forced to use NoPox to lower my nitrates and phosphates. Won’t go down naturally regardless of flow. Idea is that slower flow increases contact time to allow nitrification to reduce DO and allow denitrification to persist. Worked when my level of detritus was lower best I can assume.

As to the ratios. Seems that as long as you have one or the other but not both then neither go down. My experience. As to exact ratio that hasn’t seemed to matter plus I expect these values change through out the day based on last feed and probably something that can’t be accurately pinned down. However, raising that which is deficient has lowered both. Have come the the conclusion that having the current assumption of 100:16:1 carbon:nitrogen:phosphorus or converted to what we test of 100:10:1 carbon:nitrate:phosphate might not be required. Simply elevating that which is low to get the other to be removed naturally. Although carbon needs to be added and at some point decomposition of detritus won’t be fast enough to provide latter which then must be added manually.

Some observations that I often see mentioned and I’m not experiencing.

Yes you can dose NoPox without a skimmer. Initially water will get cloudy for a few days. If excessive, fish will be seen breathing heavy. My recommendation is to add half or less than needed then increase slowly over the week. Skimmer not needed to remove the excess assumed bacteria. I don’t.

After initial doses, the dosage can be increased to double recommendation which out concern. At one point I’ve added 4 ml daily to approximately 16 gallons of tank volume.

Post Fishless cycle, I added 15 ml of NoPox. Since there were no fish. It was a quick way to reduce nitrate to near zero and avoid a costly and unnecessary WC. Water did get cloudy quickly. MB7 was added. Two or three days later it was crystal clear. Did have to add phosphates, however to finally bring nitrates down. Head scratcher until that was done. Don’t recall the amount but I aimed for bringing it to 4 ppm to match that recommended 10:1 ratio. Wa never able to record higher than 2 ppm but nitrates were already less than half prior and perhaps much consumed.

At some point if funds are available, I’d like to setup a Fishless system with ammonium chloride, nitrates and phosphates along carbon dosed as needed along with an automatic tester to see how these interactions occur. Although being one who loses interest in getting it exact this is likely not occurring. I’ll just take results off the main display which hopefully has an automatic tester. The latter has always been a pain for me to do religiously. More of look and evaluate what’s happening kind of guy. Knowing that isn’t always accurate or best.
 
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Redfield is relatively new to me and not being one to be exact on anything and preferring to take a more holistic view then knowing exact ratios might have started as a need but now based on actual application have some to the conclusion that it may not.

Been running an experiment with a 20H using a DIY undergravel plate that provides contact as it pulls water from the one end of the tank to the other under four inches of pumice coupled with about an inch of coral skeletons on top to assist with nitrification. Goal was to exhaust DO in order to allow denitrification to take place. This was working early on but since I don’t perform WCs or remove detritus other than what gets trapped in a small floss section surrounding GAC that builds up over time. Fact is used a Turkey baster to disturb the rocks and water became quickly cloudy to the point visibility was near zero confirming there’s detritus yet to be decomposed and can only assume there must be a large volume under the gravel plate.

What I’ve learned. Detritus takes longer to decompose then assumed or perhaps I’m not supplementing with enough heterotrophic bacteria. Something I have been doing periodically but not on a schedule. Mostly when nitrates start to climb. Use MB7. Nassarius snails added don’t seem to be feeding on it. Amphipods added don’t seem to be feeding on it. Thought was that as detritus decomposes it would naturally release carbon needed for denitrification. The latter part I’ve understood was needed before learning about Redfield and from back in the 80s when I first started studying denitrification knew that a source of food was required. At the time didn’t know it was carbon.

Besides the rate at which detritus decomposes, I’ve learned that ammonia and nitrites have not spiked. Early on in order to lower nitrates I added phosphates which was the catalyst as oddly my tank is phosphate deprived unless my nitrates rise. Haven’t figured that one out yet since I don’t run GFO and only time I’ve run PhosGuard was due to a high level of diatoms early on. Could have just let it run it’s coarse but I wanted to see how quickly that worked since I’m 50 plus years of keeping fish this was my first having it.

These days I’m forced to use NoPox to lower my nitrates and phosphates. Won’t go down naturally regardless of flow. Idea is that slower flow increases contact time to allow nitrification to reduce DO and allow denitrification to persist. Worked when my level of detritus was lower best I can assume.

As to the ratios. Seems that as long as you have one or the other but not both then neither go down. My experience. As to exact ratio that hasn’t seemed to matter plus I expect these values change through out the day based on last feed and probably something that can’t be accurately pinned down. However, raising that which is deficient has lowered both. Have come the the conclusion that having the current assumption of 100:16:1 carbon:nitrogen:phosphorus or converted to what we test of 100:10:1 carbon:nitrate:phosphate might not be required. Simply elevating that which is low to get the other to be removed naturally. Although carbon needs to be added and at some point decomposition of detritus won’t be fast enough to provide latter which then must be added manually.

Some observations that I often see mentioned and I’m not experiencing.

Yes you can dose NoPox without a skimmer. Initially water will get cloudy for a few days. If excessive, fish will be seen breathing heavy. My recommendation is to add half or less than needed then increase slowly over the week. Skimmer not needed to remove the excess assumed bacteria. I don’t.

After initial doses, the dosage can be increased to double recommendation which out concern. At one point I’ve added 4 ml daily to approximately 16 gallons of tank volume.

Post Fishless cycle, I added 15 ml of NoPox. Since there were no fish. It was a quick way to reduce nitrate to near zero and avoid a costly and unnecessary WC. Water did get cloudy quickly. MB7 was added. Two or three days later it was crystal clear. Did have to add phosphates, however to finally bring nitrates down. Head scratcher until that was done. Don’t recall the amount but I aimed for bringing it to 4 ppm to match that recommended 10:1 ratio. Wa never able to record higher than 2 ppm but nitrates were already less than half prior and perhaps much consumed.

At some point if funds are available, I’d like to setup a Fishless system with ammonium chloride, nitrates and phosphates along carbon dosed as needed along with an automatic tester to see how these interactions occur. Although being one who loses interest in getting it exact this is likely not occurring. I’ll just take results off the main display which hopefully has an automatic tester. The latter has always been a pain for me to do religiously. More of look and evaluate what’s happening kind of guy. Knowing that isn’t always accurate or best.
@MnFish1 done a few studies similar to the ones you mentioned, although the main purpose of the study was to see if chlorinated tap water would kill bacteria, interesting observation were made during the study, the one I got more interested was the rock coming from a lit display thank jan more beneficial bacteria than a rock coming from a dark sump in the same system, telling me that the diversity of bacteria in the lot rock is more effective at filtration than nitrifying bacteria alone.


this is interesting also
 

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@MnFish1 done a few studies similar to the ones you mentioned, although the main purpose of the study was to see if chlorinated tap water would kill bacteria, interesting observation were made during the study, the one I got more interested was the rock coming from a lit display thank jan more beneficial bacteria than a rock coming from a dark sump in the same system, telling me that the diversity of bacteria in the lot rock is more effective at filtration than nitrifying bacteria alone.


this is interesting also
And you will have new results whether nitrifying bacteria survive 3 months! Shortly
 
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Views on algae outbreaks what do I think that causes them:

in most situations, I’ve seen someone trying to outcompete algae by starving the algae of nutrients both N and P were taken to zero in hopes to starve the algae, but instead of dying we see it coming stronger than never.

what are the ratios telling me wend N and P are limited. Wend N and P are limited it means that there is a abundance of Carbon in a tank

How will carbon affect algae:

Most algaes will do they’re own organic carbon from inorganic carbon (co2) but apparently most algaes will be able to use organic carbon in the water to fix they’re own carbon and in addition organic carbon in abundance can promote the ferrous state of iron that apparently is more easily utilised by plants.

in addition I believe that if we don’t have no3 and po4 available our biological filter will start to weaken causing some bacteria to go dormant, if we have less active bacteria in a system that means there will be less bacteria transforming ammonia in to nitrates and as result more ammonia will be available to the algae, most pest algaes will prefer ammonia to nitrates as it’s easier to utilise.

in conclusion, lowering nutrient to try and kill invasive algaes is just creating a perfect environment for algae to thrive. Imo

What could be done to avoid this
situation:


imo if found in this situation I would want to keep my parameters detectable and stable meaning that there wouldn’t be any extra available carbon or ammonia for the algae and my filter would stay strong. With the outbreak under control the addition of herbivores would finish of the job of removing the rest of the algae.
 
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How will carbon affect algae:

Most algaes will do they’re own organic carbon from inorganic carbon (co2) but apparently most algaes will be able to use organic carbon in the water to fix they’re own carbon and in addition organic carbon in abundance can promote the ferrous state of iron that apparently is more easily utilised by plants.

That does not make sense to me.

What evidence do you have that ANY marine algae uses organic carbon as a source of carbon for photosynthesis?

I cannot even imagine how that would work.

I discuss in this article how it is well studied what forms of carbon different organisms uses, and the primary choices are carbonate, bicarbonate and carbonic acid:

Photosynthesis and the Reef Aquarium, Part I: Carbon Sources by Randy Holmes-Farley - Reefkeeping.com
 
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As long as there is light strong enough for photosynthesis, in planted tanks it’s very common to add organic Carbon for better growth in addition to co2.
 

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That does not make sense to me.

What evidence do you have that ANY marine algae uses organic carbon as a source of carbon for photosynthesis?

I cannot even imagine how that would work.

I discuss in this article how it is well studied what forms of carbon different organisms uses, and the primary choices are carbonate, bicarbonate and carbonic acid:

Photosynthesis and the Reef Aquarium, Part I: Carbon Sources by Randy Holmes-Farley - Reefkeeping.com
Does this article shed light one way or the other? https://academic.oup.com/plankt/article/32/3/367/1537750
 
AS
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That does not make sense to me.

What evidence do you have that ANY marine algae uses organic carbon as a source of carbon for photosynthesis?

I cannot even imagine how that would work.

I discuss in this article how it is well studied what forms of carbon different organisms uses, and the primary choices are carbonate, bicarbonate and carbonic acid:

Photosynthesis and the Reef Aquarium, Part I: Carbon Sources by Randy Holmes-Farley - Reefkeeping.com
Thank you will have a read later on once I finish work, organic Carbon and ammonia seems to be a suspicion only and only in my view if the theory eventually is proven correct.
 
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I’ve posted the following observation in another thread to me it makes sense:


If you are still finding my theory of having a abundance of organic Carbon to be the cause of thriving pest algae’s let me add one more example that may help make the connection:

As a example I will use a tank that is experiencing a high rise in no3 and po4 unused residual nutrients. A tank with a high unused residual no3 and po4 tells me that this system has a limitation in Carbon.

most in this situation will implement a refugium, but not everyone will have the same outcome, some will report a good growth in the algae bed with high no3 and po4 and some will report little to no growth in this condition.

what many report is that in this particular condition the big difference is the strength of the light, a weak light will have no effect on the algae and a strong light will start the algae bed to grow rapidly.
By changing the weak light with a stronger light the algae is now capable to start producing they’re own organic carbon through photosynthesis for growth and as it grows no3 and po4 will be also utilised, reducing nutrients.
The main difference between some being successful at growing algae with weaker stock lights is the availability of organic carbon.
supporting my theory that a abundance of unused residual carbon will have a great impact on pest algaes growth.
 

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Does this article shed light one way or the other? https://academic.oup.com/plankt/article/32/3/367/1537750
I had a poke around at this a long time ago. It appeared to be a low light survival strategy;

 

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As long as there is light strong enough for photosynthesis, in planted tanks it’s very common to add organic Carbon for better growth in addition to co2.

That may be, but it is not any sort of evidence that algae use organic carbon as a carbon source for photosynthesis, which I contend doesn't make any sort of chemical sense in a marine environment where bicarbonate is readily available, and known to be used.

Organic carbon, when metabolized by bacteria, produces CO2. That is presumably the reason to add organic carbon in a freshwater aquarium.
 
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Reef tanks are obviously carbon limited for many species of bacteria. That's why organic carbon dosing works to drive bacteria.

I do not believe there is any evidence that any reef tank at any normal pH (say, less than 8.5) is carbon limited for photosynthesis.

Further, there is lots of evidence to the contrary: Vast numbers of reefers who have tested it themselves by dosing organic carbon. There is no evidence from these experiments that dosing organic carbon (unless it is a special organic that contains N or P) boosts coral or macroalgae growth rates.
 
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Reef tanks are obviously carbon limited for many species of bacteria. That's why organic carbon dosing works to drive bacteria.

I do not believe there is any evidence that any reef tank at any normal pH (say, less than 8.5) is carbon limited for photosynthesis.

Further, there is lots of evidence to the contrary: Vast numbers of reefers who have tested it themselves by dosing organic carbon. There is no evidence from these experiments that dosing organic carbon (unless it is a special organic that contains N or P) boosts coral or macroalgae growth rates.
You are right, but why do I keep getting close to what’s happening every time I apply the theoretical formula to a known issue, would it be just coincidence? Am not a strong believer of multiple coincidences.

For example I seen earlier today a tank that looks like it got some sort of dinoflagellates. The changes on the residual unused nutrient trend is po4 and no3 going down. If I were to apply the theoretical formula I would conclude that that particular tank is starting to be abundant in Carbon.
Could it be that the dinoflagellates are using the nutrients as a result of photosynthesis allowing for carbon to build up. If the theory was to be right could we not just reduce light and increase nitrogen and phosphorus to reduce the availability of organic carbon so that in the absence of photosynthesis denning the dinoflagellates that could go into survival mode and utilise the organic carbon to stay alive?

I do apologise if I keep making weird connection it’s just for me it’s making sense almost every time I apply the theoretical formula. In the end of the day I don’t have a degree to explain things as well as you do.
 

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I’ve posted the following observation in another thread to me it makes sense:


If you are still finding my theory of having a abundance of organic Carbon to be the cause of thriving pest algae’s let me add one more example that may help make the connection:

As a example I will use a tank that is experiencing a high rise in no3 and po4 unused residual nutrients. A tank with a high unused residual no3 and po4 tells me that this system has a limitation in Carbon.

most in this situation will implement a refugium, but not everyone will have the same outcome, some will report a good growth in the algae bed with high no3 and po4 and some will report little to no growth in this condition.

what many report is that in this particular condition the big difference is the strength of the light, a weak light will have no effect on the algae and a strong light will start the algae bed to grow rapidly.
By changing the weak light with a stronger light the algae is now capable to start producing they’re own organic carbon through photosynthesis for growth and as it grows no3 and po4 will be also utilised, reducing nutrients.
The main difference between some being successful at growing algae with weaker stock lights is the availability of organic carbon.
supporting my theory that a abundance of unused residual carbon will have a great impact on pest algaes growth.

It does not make any sense and is not correct.

I know you strongly believe what you are writing, but I don't want folks reading this to think it is a simple true statement.
 

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You are right, but why do I keep getting close to what’s happening every time I apply the theoretical formula to a known issue, would it be just coincidence? Am not a strong believer of multiple coincidences.

For example I seen earlier today a tank that looks like it got some sort of dinoflagellates. The changes on the residual unused nutrient trend is po4 and no3 going down. If I were to apply the theoretical formula I would conclude that that particular tank is starting to be abundant in Carbon.
Could it be that the dinoflagellates are using the nutrients as a result of photosynthesis allowing for carbon to build up. If the theory was to be right could we not just reduce light and increase nitrogen and phosphorus to reduce the availability of organic carbon so that in the absence of photosynthesis denning the dinoflagellates that could go into survival mode and utilise the organic carbon to stay alive?

I do apologise if I keep making weird connection it’s just for me it’s making sense almost every time I apply the theoretical formula. In the end of the day I don’t have a degree to explain things as well as you do.

I'm almost at a lose for words. What prediction did you make that is correct?

You have no evidence that any prediction you have made on any system is accurate except your saying it is true.

You declined to predict what is limiting in the REAL cases I posted where IT IS KNOWN what is limiting.

That's a real test.
 

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Does this article shed any light (pun intended) on the discussion? I know we're not talking about 'macro algae here' - but the effect of carbon on pest algae: "Growth on organic carbon substrates promotes higher biomass, lipid, and carbohydrate productivity, which further triggers the yield of various biomolecules. Since, the current mass culture practices primarily employ open pond and tubular photobioreactors for phototrophic growth, they become cost intensive and economically non-viable."
 
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