Theory on nutrient ratios and algae/bacteria

[Brew12]

I really wasn't aware that many people used this type of silica sand in their tanks

Another article I read was more strong on the fact that 'good quality' sand does not leach much silica

I don't think quartz sand is used in new systems much at all any more, of any quality. I do know some people who have set up very large systems have used it but it is much less common than it used to be. Aragonite has become the preference. The only issue with these sands and silicates is with contaminants in the sand. Caribsea now advertises their dry sand at 99%+ pure aragonite. I don't understand why they don't make the same claim for their live sand products.
Eden Tropics states their substrate is 95% pure aragonite so there is a little more likelyhood of silicate contamination there.

I believe many older tanks do use quartz sand which, as Lasse pointed out, are susceptible to leaching silicates.

and that even RODI water is likely the highest source of silicates in the tank (because people dont maintain their RODI)

 

[MnFish1]

@Brew12 I actually enjoyed the discussion of the science part - as a microbiologist I find it interesting - so I hope you aren't taking my comments personally. I just read the article on Dinos (which was interesting) - the take home message I got is they can live with multiple sources of 'N' - N2-->NH4, Nitrate, etc. They thrive in high nitrates - and low nitrates. I then got to thinking about the theory that 'elevating nitrate and phosphate' (which are the things we can test - but of course other things are elevated too) prevents dinoflagellate growth - is that really a good strategy - or an anecdote? I just think the complexities of this are far too difficult to make any clear statement to benefit our tanks - or am I all wet?

By the way - its not like 'all dinoflagellates are bad'. So if you make your tank inhabitable for the 'bad ones' are you also then going to affect the 'good ones'?

 

[Brew12]

I feel my tank really took off once I embraced all the "pests". Now I primarily feed and care for the flat worms, bristle worms, aiptasia, sponges, algae, bacteria and such. Which sounds absolutely ridiculous. But feeding the fish and corals has become a bit of an afterthought. The only adjustment I have had to make is to deliberately stock the tank with pest species predators - a Melanurus wrasse for all the worms, Rabbitfish and Tang for the algae, Peppermint Shrimp for the aiptasia, and so on. Seems counter-intuitive perhaps but these pest organisms are pests in large measure because they are so effective at using tank nutrients. Once I stopped fighting the pests and started looking at them as part of the food chain my tank, fish and corals became much healthier. Now I have the world's fattest wrasse.

This is exactly the way I feel now. Everything is food for something. The more diversified the layers of the food chain the more balanced and healthier the system will be.

It seems like hobbyists pay much more attention to the top of the food chain than the bottom. We know Rabbitfish and Tang eat certain algaes. We know that Peppermint Shrimp and Filefish eat aiptasia. We know Melanurus wrasses eat the worms.
Why don't we look at the lowest levels of the food chain the same way? Cyanobacteria will mostly eat phosphates. Dinoflagellates will mostly eat nitrates. Phytoplankton eats a more balanced amount of nitrates and phosphates. "Non harmful" marine bacteria eats a higher percentage of nitrates to phosphates than phytoplankton. Why don't we pay as much attention to this part of the food chain as we do the top? I guess it is because we can't observe it.

 

[watchguy123]

@Lasse. I have presumed that ceramic material like siporax would not have soluble silica. What makes you think it does.

Another gap in my knowledge base!!!

 

[MnFish1]

Actually, what you pointed out agreed with what I was saying. You accused me of singling out a single part of that post. The reason I didn't mention the rest of it is that the only other part I disagreed with was where you said you disagreed with me. Everything else you stated was exactly in line with what I stated in my original post. I'm not sure why you feel like you were disagreeing with me or why what I was saying isn't in line with the studies.

In your original post, you (maybe I misinterpreted it) implied that varying N/P ratios favor certain types of bacteria, non harmful one ratio, harmful another ratio - and the dns are all over the place - but require nitrate. (You also asked people to tear the argument apart)

In re-reading my response to you - I probably used in incorrect word - I used the word anecdote to describe your theory - I didnt mean to imply that different bacteria dont like different conditions - I meant its anecdotal to the maintenance of a 'marine reef tank'. All I said was that the studies you quoted do to necessarily apply to reef aquaria - in that the N/P amounts were skewed far from what we would normally see in our tanks. I.e., how do we take those studies - and apply it to our daily reef keeping. No more no less. My opinion is that it is an impossibility to use this data meaningfully in our systems.

 

[Brew12]

I actually enjoyed the discussion of the science part - as a microbiologist I find it interesting - so I hope you aren't taking my comments personally.

I've just found your comments confusing. If I were offended by them I wouldn't keep responding. Especially when you say you don't agree with me on something and then state that the correct thing is exactly what I had said. I don't understand the logic of saying that collecting cyanobacteria from an estuary to study in a lab means the results some how don't apply to an aquarium because they weren't taken from an aquarium

They thrive in high nitrates - and low nitrates.

While they did mention for a strain of dino's what the study showed more is that they have interesting and varied survival methods for low nitrates.

I then got to thinking about the theory that 'elevating nitrate and phosphate' (which are the things we can test - but of course other things are elevated too) prevents dinoflagellate growth - is that really a good strategy - or an anecdote?

I think this is what is causing so much confusion so I'll keep repeating it again. We cannot test for nitrate and phosphate or the ratio they exist in our systems. We can only test for NO3 and PO4 in the water which is only one form that the N and P can exist in within our tanks.

If we understand the nutrient consumption of what we can see in our systems we will have a much better idea of the balance of N and P in our tanks. For example, having cyanobacteria can mean we have high P or low N. It is also possible that P and N are balanced but "more desirable" growth is being inhibited by a lack of trace elements or being limited through predation.

By the way - its not like 'all dinoflagellates are bad'. So if you make your tank inhabitable for the 'bad ones' are you also then going to affect the 'good ones'?

I don't think any dino's are bad. They just are. I don't want them visible in my system so I've taken a Sun Tzu approach which is to learn my enemy. I don't blame the dino's for my inability to maintain my system in a way that keeps their growth in check.

 

[MnFish1]

Why don't we look at the lowest levels of the food chain the same way? Cyanobacteria will mostly eat phosphates. Dinoflagellates will mostly eat nitrates. Phytoplankton eats a more balanced amount of nitrates and phosphates. "Non harmful" marine bacteria eats a higher percentage of nitrates to phosphates than phytoplankton. Why don't we pay as much attention to this part of the food chain as we do the top? I guess it is because we can't observe it.

This is why:

The importance of nitrogen (N) versus phosphorus (P) in explaining total cyanobacterial biovolume, the biovolume of specific cyanobacterial taxa, and the incidence of cyanotoxins was determined for 102 north German lakes, using methods to separate the effects of joint variation in N and P concentration from those of differential variation in N versus P. While the positive relationship between total cyanobacteria biovolume and P concentration disappeared at high P concentrations, cyanobacteria biovolume increased continually with N concentration, indicating potential N limitation in highly P enriched lakes. The biovolumes of all cyanobacterial taxa were higher in lakes with above average joint NP concentrations, although the relative biovolumes of some Nostocales were higher in less enriched lakes. Taxa were found to have diverse responses to differential N versus P concentration, and the differences between taxa were not consistent with the hypothesis that potentially N2-fixing Nostocales taxa would be favoured in low N relative to P conditions. In particular Aphanizomenon gracile and the subtropical invasive species Cylindrospermopsis raciborskii often reached their highest biovolumes in lakes with high nitrogen relative to phosphorus concentration. Concentrations of all cyanotoxin groups increased with increasing TP and TN, congruent with the biovolumes of their likely producers. Microcystin concentration was strongly correlated with the biovolume of Planktothrix agardhii but concentrations of anatoxin, cylindrospermopsin and paralytic shellfish poison were not strongly related to any individual taxa. Cyanobacteria should not be treated as a single group when considering the potential effects of changes in nutrient loading on phytoplankton community structure and neither should the N2-fixing Nostocales. This is of particular importance when considering the occurrence of cyanotoxins, as the two most abundant potentially toxin producing Nostocales in our study were found in lakes with high N relative to P enrichment.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3376147/

 

[MnFish1]

double post

 

[Brew12]

In your original post, you (maybe I misinterpreted it) implied that varying N/P ratios favor certain types of bacteria, non harmful one ratio, harmful another ratio - and the dns are all over the place - but require nitrate. (You also asked people to tear the argument apart)

I would ask that you read my OP again. What I did is state the known consumption ratio of different species. I never stated that the ratio of N: P in the water would impact the preference of what was going to grow. That doesn't happen unless a limit is reached which opens the door to the "non beneficial" bacteria.

 

[Brew12]

While the positive relationship between total cyanobacteria biovolume and P concentration disappeared at high P concentrations, cyanobacteria biovolume increased continually with N concentration, indicating potential N limitation in highly P enriched lakes.

Which makes sense because even though cyanobacteria typically consume much more P than most bio's they still require at least as much N as P, and sometimes much more N than P.

Cyanobacteria should not be treated as a single group when considering the potential effects of changes in nutrient loading on phytoplankton community structure and neither should the N2-fixing Nostocales.

Now this is a very important consideration. Cyanobacteria are a large and diverse group. I doubt that many reefers would even recognize cyano in their tank in many of its forms. There are some strains that fall well outside the norms of the species as a whole. I don't believe that this invalidates all generalized discussions on cyanobacteria but it is important to keep this in mind. Any method of treatment may not work against every strain of cyano.

A great example of this is Spirulina. Many people think of this as an algae yet it is actually a form of cyanobacteria. Most cyanobacteria removal products won't hurt this stuff.

 

[MnFish1]

I would ask that you read my OP again. What I did is state the known consumption ratio of different species. I never stated that the ratio of N: P in the water would impact the preference of what was going to grow. That doesn't happen unless a limit is reached which opens the door to the "non beneficial" bacteria.

According to Redfield (via a summary in wikipedia)

Understanding that the problem is akin to the classical the chicken or the egg causality dilemma, Redfield proposed two mutually non-exclusive mechanisms:

I) The N/P in plankton tends to the N/P composition of seawater. Specifically, phytoplankton species with different N and P requirements compete and, as the result, balance each other so that “the ratio of the elements in the plankton as a whole might come to reflect the ratio of the nutrient substances in sea water rather closely” (Redfield 1934).

II) The N/P in seawater “must tend to approach that characteristic of protoplasm in general” (Redfield 1934). Furthermore, Redfield proposed thermostat like scenario in which the activities of nitrogen fixers and denitrifies keep the nitrate to phosphate ratio in the seawater near the requirements in the protoplasm. Considering that at the time little was known about the composition of “protoplasm,” Redfield did not attempt to explain why its N/P ratio should be approximately 16:1.

In 1958, almost a quarter century after first discovering the ratios, Redfield leaned toward the latter mechanism proposing in his seminal manuscript the idea of "the biological control of chemical factors" in the ocean (Redfield, 1958). Redfield proposed that the ratio of Nitrogen to Phosphorus in plankton resulted in the global ocean having a remarkably similar ratio of dissolved nitrate to phosphate (16:1). He considered how the cycles of not just N and P but also C and O could interact to result in this match.

Lets start over: I'll 'tear it apart' (and agree with some of it) piece by piece at your request (in your original post). Because the studies you quoted DID focus on the levels of nitrate and phosphate in the environment - and the recommendations in your original post DO reference levels of nitrate/PO4 (i.e. adding them or reducing them) so perhaps it lead me off track a bit.

My interest in this started when I learned about the Redfield Ratio where oceanic phytoplankton has a nitrogen to phosphorus ratio of 16:1. Unfortunately, I had no idea what to do with this knowledge so it was pretty worthless. Of course, I found out about this because of research I was doing to combat an algae problem. I'll spare you guys the joys of my battle that took me from algae to cyanobacteria and from cyanobacteria into dinoflagellates. Through these battles I learned a lot about the role of nutrients in my tank. This is what I think I have found and how the N: P ratio can be used by reefers who aren't purposely running low nutrient systems.

This implied what you were posting about was personal experience/anecdotal. You may have looked at all the science - I just was reading what you posted and perhaps misinterpreted (sorry)

Non harmful marine bacteria with a typical N: P ratio of 50:1 so it will consume nitrates faster than phosphates. This is the bacteria whose growth is encouraged through carbon dosing. This means people who carbon dose are likely to need a phosphate reducer, also. Too much carbon dosing can lead to cyanobacteria.

There is no reference for this. How is 'non-harmful bacteria' defined? What are the 'non-harmful' bacteria that are increased with carbon? Most bacteria increase with carbon dosing. Im not sure that you can assume that because 'non-harmful' bacteria have an N/P ratio of 50:1 implies that one needs a phosphate reducer. Thats not to say that people that dose carbon don't need a phosphate reducer - just that it has no relation to the N/P ratio or the bacteria. For example I would call nitrosomonas a 'non-harmful' bacteria - it will certainly rise with nitrate contentration.... Bacteria are not phytoplankton - so you cannot really compare Redfields conclusions to bacteria in any case. I.e. the ratio of 50:1 in bacteria may have a completely different reason than in a photosynthetic organism (cyano and Dino)

Cyanobacteria has a N/P ratio of between 1:1 and 5:1. This gives it an ability to thrive in a low nitrate environment. To combat cyano, either add a phosphate remover or add nitrates.

As in the article I just posted - different cyanobacteria - there are LOTS of them - grow at different nitrate levels (high and low) - so how does adding nitrate help? How does the ratio imply that adding PO4 will help? (in this instance the ratio you quote is a factor of 500% different). I do not think you can use the ratio of the C/N/P in the organisms to suggest that this gives cyanobacteria an ability to thrive in a low nitrate environment.

Dinoflagellates have an N: P ratio that is all over the board. One thing they have in common is a high need for Nitrates.
They have unique ways to acquire and store nitrates which does mess up the N: P ratio. If you do have them one possible way to combat them is dosing phosphates. Another option is to add silicates which will shift production from dino's to diatoms. Carbon dosing will be slow, but should also be effective.

This is not true - not all dinos have a high need for nitrates (depending on what 'high' means - you dont explain it). The Purpose of the Redfield ratio was to show the consistency of phytoplankton with regards to their C/N/P ratios in all areas of the ocean. There is no rationale given in your post as to why the 'ratio of C/N/P 'being all over the place' has anything to do with dosing phosphates or silicates as your post suggests. Zooxanthellae are dinoflagellates. Many people say that a way to rid an aquarium of dinoflagellates is to allow nutrient levels to rise (including nitrates) ... (I dont necessarily believe this - but - its all over this forum). Adding PO4 may help - but I dont see the relation to the ratio

If you have Cyano and/or Dino's and have detectable levels of both NO3 and PO4 I would suggest adding an Iron supplement. A reef tank will want to grow algae. If you have both nutrients the missing link may be the iron needed to support the algae growth. Especially if you have a system that was growing algae well and then tapered off.

I assume you mean algae in a refugium - rather than encouraging algae in the tank. There are many articles stating that iron benefits both cyanobacteria and dinoflagellates. But what you say may make sense.

So - my conclusion based on your post - 1. The N/P ratio is not measurable in the aquarium (nor is it possible to measure the N/P of the bacteria in the aquarium. 2. A refugium with algae and iron supplementation will outcompete cyanobacteria and dinoflagellates. I support the idea that fiddling with the chemistry of the water will likely improve/aggravate the presence of certain bacteria.

IMHO - and its only my opinion - the rest of the recommendations are taking an extremely complex topic and trying to generalize it to your personal experience. There is no reason to assume that the ratios you are quoting are helpful (i.e. the ratio in bacteria may have quite a different meaning is different than the ratio in cyanobacteria and dinoflagellates. I have read a bunch of the science and depending on which part of the ocean, which species of cyano or Dino you are studying, the temperature of the water, other local influences of the study area (Fe concentration), you can find justification for almost any position on the N/P ratio of the phytoplankton present.

 

[Brew12]

According to Redfield (via a summary in wikipedia)

Understanding that the problem is akin to the classical the chicken or the egg causality dilemma, Redfield proposed two mutually non-exclusive mechanisms:

I) The N in plankton tends to the N composition of seawater. Specifically, phytoplankton species with different N and P requirements compete and, as the result, balance each other so that “the ratio of the elements in the plankton as a whole might come to reflect the ratio of the nutrient substances in sea water rather closely” (Redfield 1934).

II) The N in seawater “must tend to approach that characteristic of protoplasm in general” (Redfield 1934). Furthermore, Redfield proposed thermostat like scenario in which the activities of nitrogen fixers and denitrifies keep the nitrate to phosphate ratio in the seawater near the requirements in the protoplasm. Considering that at the time little was known about the composition of “protoplasm,” Redfield did not attempt to explain why its N ratio should be approximately 16:1.

In 1958, almost a quarter century after first discovering the ratios, Redfield leaned toward the latter mechanism proposing in his seminal manuscript the idea of "the biological control of chemical factors" in the ocean (Redfield, 1958). Redfield proposed that the ratio of Nitrogen to Phosphorus in plankton resulted in the global ocean having a remarkably similar ratio of dissolved nitrate to phosphate (16:1). He considered how the cycles of not just N and P but also C and O could interact to result in this match.

Lets start over: I'll 'tear it apart' (and agree with some of it) piece by piece at your request (in your original post). Because the studies you quoted DID focus on the levels of nitrate and phosphate in the environment - and the recommendations in your original post DO reference levels of nitrate/PO4 (i.e. adding them or reducing them) so perhaps it lead me off track a bit.



This implied what you were posting about was personal experience/anecdotal. You may have looked at all the science - I just was reading what you posted and perhaps misinterpreted (sorry)



There is no reference for this. How is 'non-harmful bacteria' defined? What are the 'non-harmful' bacteria that are increased with carbon? Most bacteria increase with carbon dosing. Im not sure that you can assume that because 'non-harmful' bacteria have an N ratio of 50:1 implies that one needs a phosphate reducer. Thats not to say that people that dose carbon don't need a phosphate reducer - just that it has no relation to the N ratio or the bacteria. For example I would call nitrosomonas a 'non-harmful' bacteria - it will certainly rise with nitrate contentration.... Bacteria are not phytoplankton - so you cannot really compare Redfields conclusions to bacteria in any case. I.e. the ratio of 50:1 in bacteria may have a completely different reason than in a photosynthetic organism (cyano and Dino)



As in the article I just posted - different cyanobacteria - there are LOTS of them - grow at different nitrate levels (high and low) - so how does adding nitrate help? How does the ratio imply that adding PO4 will help? (in this instance the ratio you quote is a factor of 500% different). I do not think you can use the ratio of the C:N in the organisms to suggest that this gives cyanobacteria an ability to thrive in a low nitrate environment.



This is not true - not all dinos have a high need for nitrates (depending on what 'high' means - you dont explain it). The Purpose of the Redfield ratio was to show the consistency of phytoplankton with regards to their C:N ratios in all areas of the ocean. There is no rationale given in your post as to why the 'ratio of C:N 'being all over the place' has anything to do with dosing phosphates or silicates as your post suggests. Zooxanthellae are dinoflagellates. Many people say that a way to rid an aquarium of dinoflagellates is to allow nutrient levels to rise (including nitrates) ... (I dont necessarily believe this - but - its all over this forum). Adding PO4 may help - but I dont see the relation to the ratio



I assume you mean algae in a refugium - rather than encouraging algae in the tank. There are many articles stating that iron benefits both cyanobacteria and dinoflagellates. But what you say may make sense.

So - my conclusion based on your post - 1. The N ratio is not measurable in the aquarium (nor is it possible to measure the N of the bacteria in the aquarium. 2. A refugium with algae and iron supplementation will outcompete cyanobacteria and dinoflagellates. I support the idea that fiddling with the chemistry of the water will likely improve/aggravate the presence of certain bacteria.

IMHO - and its only my opinion - the rest of the recommendations are taking an extremely complex topic and trying to generalize it to your personal experience. There is no reason to assume that the ratios you are quoting are helpful (i.e. the ratio in bacteria may have quite a different meaning is different than the ratio in cyanobacteria and dinoflagellates. I have read a bunch of the science and depending on which part of the ocean, which species of cyano or Dino you are studying, the temperature of the water, other local influences of the study area (Fe concentration), you can find justification for almost any position on the N ratio of the phytoplankton present.

Oh.. and now you aren't even taking it seriously? You really have to mock it by putting a everywhere?

I had to go back and edit my OP to get all the smiley faces out.

I don't have time to respond right now, but this is the type of conversation I was hoping to spark.

 

[Scott Campbell]

This is exactly the way I feel now. Everything is food for something. The more diversified the layers of the food chain the more balanced and healthier the system will be.

It seems like hobbyists pay much more attention to the top of the food chain than the bottom. We know Rabbitfish and Tang eat certain algaes. We know that Peppermint Shrimp and Filefish eat aiptasia. We know Melanurus wrasses eat the worms.
Why don't we look at the lowest levels of the food chain the same way? Cyanobacteria will mostly eat phosphates. Dinoflagellates will mostly eat nitrates. Phytoplankton eats a more balanced amount of nitrates and phosphates. "Non harmful" marine bacteria eats a higher percentage of nitrates to phosphates than phytoplankton. Why don't we pay as much attention to this part of the food chain as we do the top? I guess it is because we can't observe it.

What is there to do at the bottom of the food chain? I'm intrigued by what you are saying but I'm not sure what are you recommending? Are you thinking we should be target feeding phytoplankton to offset cyanobacteria or something along those lines? My experience has been that the bottom of the food chain is always in flux. And that is reflected in waxing or waning populations of algae, bacteria and microfauna. As long as I can manage those changing populations at the top with predators, harvesting algae and skimming out bacteria - I'm not sure why I would want to attempt to control at the lowest levels of the food chain? If it was even possible?

 

[Lasse]

As in the article I just posted - different cyanobacteria - there are LOTS of them - grow at different nitrate levels (high and low) - so how does adding nitrate help? How does the ratio imply that adding PO4 will help? (in this instance the ratio you quote is a factor of 500% different). I do not think you can use the ratio of the C:N in the organisms to suggest that this gives cyanobacteria an ability to thrive in a low nitrate environment.

The article you posted DO NOT mention nitrate or phosphate at all. Its Total N and Total P off the water column that they compare with. It means that the analyse include all sources of N and P – including organic particular N and P. There is a lot of studies that concentrate on NO3 levels in lakes – and there is the experiences somewhat different – there is a clear trend of no or less cyanobacteria blooms there the NO3 levels are over 2 ppm.

You can´t translate total N with NO3 in this case

Sincerely Lasse

 

[MnFish1]

Oh.. and now you aren't even taking it seriously? You really have to mock it by putting a everywhere?

I had to go back and edit my OP to get all the smiley faces out.

I don't have time to respond right now, but this is the type of conversation I was hoping to spark.

HEY - I EDITED ALL THE Smileys OUT (which are put their by R2R

 

[saltyfilmfolks]

Why don't we pay as much attention to this part of the food chain as we do the top

I do.

 

[Lasse]

@Lasse. I have presumed that ceramic material like siporax would not have soluble silica. What makes you think it does.

Another gap in my knowledge base!!!

Own experiences.


My DSB is constructed with a small water column in the bottom. See the first pages of my build thread. First layer of the DSB consist of 3 cm siporax followed of coral sand of different size. Total depth of DSB 15 cm. In this bed I have a slow reversed flow of water (from the bottom and up). In the start I put in skimate and organic carbon in the bottom layer of the siporax – in order to create anaerobic condition. I had a very slow flow of water through the bed

October 2016 (aquarium half a year old) – SI levels 281.00 μg/l

January 2017 – Si levels 1071 μg/l

May 2017 – Si levels 1114 μg/l

June 2017 – Si levels 7035 μg/l

Sept 2017 – Si levels 4093 μg/l

One week before I send in the test in June 2017 I had to change (and rise) the flow through the sandbed and hence the siporax bed. It was highly anaerobic at that time.


The aquarium in Sjöfartsmuseet Gothenburg (it’s a public aquarium there I work sometimes) has similar experiences with thing containing silica and anaerobic conditions. In one aquarium – a sand filter containing silica sand of mistakes was closed down every night and started every day for a month. The discover that the filter become anaerobic and the Si levels arise in that system. They put the filter to run without stop during nights and after a while – the Si level was down to normal concentrations again. In order to test they did an anaerobic filter of Siporax and in that system – the Si levels arise as aspected. Before they did the Siporax filter anaerobic – it has run as an aerobic filter without any rising levels of Si. I have seen this for 3 different aquariums – and I´m therefore rather sure that things that contain Si and anaerobic conditions will rise the waters concentration of Si. At least – people shal have this in mind if they use siporax

Sorry for late answer but other things show up

Sincerely Lasse

 

[MnFish1]

The article you posted DO NOT mention nitrate or phosphate at all. Its Total N and Total P off the water column that they compare with. It means that the analyse include all sources of N and P – including organic particular N and P. There is a lot of studies that concentrate on NO3 levels in lakes – and there is the experiences somewhat different – there is a clear trend of no or less cyanobacteria blooms there the NO3 levels are over 2 ppm.

You can´t translate total N with NO3 in this case

Sincerely Lasse

Yes - thats correct - I substituted Nitrate for nitrogen. Part of the problem with the topic in general is that there is the N ratio (in the Redfield ratio which is the composition of the plankton themselves), then there is the N ratio quoted in some of the studies (which is concentration in the water) then there is the problem with N and NO3 and P and PO4. The point was that there is a huge variability in the abilities of cyanobacteria to consume nitrate and phosphate (and N2 --->ammonia). Again - as you said in your previous post the levels dont depend on nitrate alone - but sulfate, phosphate and other sources. Some of this variability probably relates to differences between species. My only point was different cyanobacteria can grow in markedly different environments with regards to Nitrogen and Phosphorous. Which I think is also what happens in certain lakes. One article I read stated that in combination with other toxins or different species of Cyanobacteria, a higher nitrate level can be inhibitory - but that its not clear that it is the nitrate itself thats causing the lower level of that cyanobacteria - this article stated its one problems with doing studies in 'natural lakes - as compared to lakes where they artificially add N (Ammonia and Nitrate) and P.

 

[Lasse]

There is a very good Swedish study from 2006 that totally change the way our authorities handle the problem with cyanobacteria blooms in the Baltic – especially in the coast around Stockholm. I take also up the discussion of how the mat building benthic cyanobacteria fix its nitrogen as I stated in an earlier post. Unfortunately, it is in Swedish, but I post a link to it anyhow. The part about the benthic cyanobacteria is in the end of the article chap 5.7. There is an English summary at page 8. I think that you can copy and run Google translate and get an idea of it

Sincerely Lasse

 

[Lasse]

I´m convinced that lack of NO3 and somehow lack of PO4 in the water column is one of the things causing cyanobacteria bloom in our aquariums. I´m also lending to that it is so even for the Dino problems. Sometimes – you can have outbreak in high nutrient system but for the cyanobacteria part - I´m convinced there is a lack of micronutrients like iron in these cases.

But if I´m right - I do not know?

Sincerely Lasse