Could we utilise the Redfield ratio a little better in aquaria?

[sixty_reefer]

Redfield has several uses in science one of my favourite implementations of Redfield ratio is to determine nutrient limitations in aquaria.

With the main reference ratio being 16:1, this number is widely agreed between aquarists including many experts on this forum for the assimilation rate of N and P for heterotrophic bacteria during carbon dosing and it’s also agreed between several expert aquarist that if a reef tank is limited by P for example that we cannot lower nitrates using organic carbon due to the bacteria becoming limited in one nutrient.

My point being that would we gain more as aquarist by understanding how Redfield nutrient limitations work?

Some examples were Redfield could be used as a example could be in the battle against nuisances algae like GHA as many folks do tend deplete a system from phosphates causing their biological filter to be unable to assimilate nutrients that could compete with the algae for example.

There is many other ways that I can think were we could use Redfield nutrient limitations in order to improve coral growth and reducing nuisances although I would like to hear your thoughts.


If you read all this way please don’t just post saying that you like to keep your No3 and Po4 at the same ratio as Redfield as that’s not how it’s used, that’s just a preference on how someone keeps their residual N and P, sorry had to be said.

 

[rtparty]

The term should be abolished from the hobby completely. I see more people screw their systems up chasing this ratio (which has nothing to do with the water surrounding the organisms) than those fixing anything chasing it.

Hans-Werner has some greats posts about ratios and how they don’t fit.

Here is a good one:

NP Plus - Phosphate / Nitrate ratio

According to previous threads on NP Plus, I am suppose to test phosphate only because nitrate is expected to remain 0 while using NP Plus. I did not know that at first so I kept dumping NP Plus and testing my nitrate. I finally got a Hanna Phosphate test kit and it is reading 0.39 for...

www.reef2reef.com

 

[GARRIGA]

That topics has been exhausted and quick search will bring you more than I’m willing to read. No clue if it actually works or doesn’t but know I’ve had to add phosphates to drop nitrate post cycle using carbon. All I need to know or care to know. Practicality over mind numbing

 

[sixty_reefer]

The term should be abolished from the hobby completely. I see more people screw their systems up chasing this ratio (which has nothing to do with the water surrounding the organisms) than those fixing anything chasing it.

Hans-Werner has some greats posts about ratios and how they don’t fit.

Here is a good one:

NP Plus - Phosphate / Nitrate ratio

According to previous threads on NP Plus, I am suppose to test phosphate only because nitrate is expected to remain 0 while using NP Plus. I did not know that at first so I kept dumping NP Plus and testing my nitrate. I finally got a Hanna Phosphate test kit and it is reading 0.39 for...

www.reef2reef.com

Have you even read the post? Nutrient limitation is an actual correct implementation of Redfield ratio by many folks in science. I would advice you to read the last phrase on my post

Edit: you could as Hans-Werner what would happen if phosphate was to bottom out wile using the pellets and if the ratio of the pellets at removing nitrates and phosphates are close to 16:1

 

[sixty_reefer]

That topics has been exhausted and quick search will bring you more than I’m willing to read. No clue if it actually works or doesn’t but know I’ve had to add phosphates to drop nitrate post cycle using carbon. All I need to know or care to know. Practicality over mind numbing

It’s not a easy topic, although essential in aquaria imo

 

[GARRIGA]

It’s not a easy topic, although essential in aquaria imo

Why I don’t bother with it beyond knowing both elements needed for both to be consumed. Has been discussed ad nauseam and consensus by resident scientist that in aquaria it’s not pertinent. At least not in the context of the ratio promoted.

Seeing as you appear to have a background on this might be better served going there and adding value because many always wanting to learn the nuance and geek the hobby to its max. I get lost then as most of it goes over my head but likely just because more complex then my KISS mantra

 

[rtparty]

Have you even read the post? Nutrient limitation is an actual correct implementation of Redfield ratio by many folks in science. I would advice you to read the last phrase on my post

Edit: you could as Hans-Werner what would happen if phosphate was to bottom out wile using the pellets and if the ratio of the pellets at removing nitrates and phosphates are close to 16:1

Yes, I read the post. It doesn't make the Redfield ratio any more relevant. Again, the ratio we keep in the water makes no difference. Just make sure there is carbon, nitrogen, and phosphorous available for the organisms. The ratio won't solve anything.

Go read the thread I posted and askl Hans yourself. Bet your question is answered if you read the thread though

 

[rtparty]

It’s not a easy topic, although essential in aquaria imo

What is essentail about the ratio? What exact ratio should we be keeping in our systems and what ratio solves each issue? Do dinoflagellates require a certain ratio but GHA another? Does cyano come to town and wreck everything when you aren't a specific ratio?

 

[sixty_reefer]

What is essentail about the ratio? What exact ratio should we be keeping in our systems and what ratio solves each issue? Do dinoflagellates require a certain ratio but GHA another? Does cyano come to town and wreck everything when you aren't a specific ratio?

Since you asked politely, how does one person knows that during carbon dosing you can’t allow phosphate to bottom out for example? You would be surprised on how everything you mentioned above is connected to nutrient limitations.

 

[Randy Holmes-Farley]

Have you even read the post? Nutrient limitation is an actual correct implementation of Redfield ratio by many folks in science. I would advice you to read the last phrase on my post

Edit: you could as Hans-Werner what would happen if phosphate was to bottom out wile using the pellets and if the ratio of the pellets at removing nitrates and phosphates are close to 16:1

How does a ratio say if either or both are too low and limiting?

Ratio is 10. Is it limiting? Not possible to answer.

 

[ReneReef]

Could we utilise the Redfield ratio a little better in aquaria?​

Yes, by forgetting about it permanently.

 

[sixty_reefer]

How does a ratio say if either or both are too low and limiting?

Ratio is 10. Is it limiting? Not possible to answer.

It’s not possible if only one number is known, yes you are right there although over the years we have learned that we do know two numbers in the ratio, we do know the N and P assimilation ratios for heterotrophic bacteria

Reefkeeping Magazine - Vinegar Dosing Methodology for the Marine Aquarium

Reefkeeping ...an online magazine for the marine aquarist.

reefkeeping.com

Above you and Cliff Babcok determine that wile carbon dosing, nitrates and phosphate will be reduced on a average ratio of 16 to 1.
Knowing that the bacteria that is being stimulated in growth by the carbon dosing has a 16:1 nutrient requirement in order to grow and divide it’s possible to determine the limiting factor for heterotrophic bacteria that is the main strain of bacteria present in reef aquaria by just keeping track of residual N and P.

Edit:
In the article it’s recommended to use GFO to reduce high residual Po4 although if you know that the ratio is 16:1 a option to GFO would be to add nitrates to the carbon dosing to keep the balance on reducing Po4 to a desired residual.
Nitrates are much cheaper than GFO imo

 

[sixty_reefer]

Could we utilise the Redfield ratio a little better in aquaria?​

Yes, by forgetting about it permanently.

do you mean that nutrient limitations don’t have place in aquaria?

 

[ReneReef]

do you mean that nutrient limitations don’t have place in aquaria?

No.

Do you mean that:
If available P is 1000 and N is 16000, all is fine. But if P is 500 and N 16000, there is too little P and everything stops growing?
(I’m using fictitious numbers here)

If yes, then good luck with that.
If not, then who cares about ratios.

Let me put it another way, if you eat an unbalanced meal every day (fastfood high in fat and sugar), according to you you won’t grow fat because your nutrients are limited by protein and fibre being low?

Also Redfield has three parts in his ratio. You skip the C. So what you are calling the Redfield ratio is not it.
You also say to use NO3 as measure for total N. That way you’re missing a ton of N. Especially in an aquarium full of corals that take up ammonia before you’ll see any nitrate.
I could go on and on…

Basically, Redfield would turn over in his grave if he could for the vast misuse of his research in this hobby.

So, yes, forget about the Redfield ratio and keep nutrients available for organisms to take up in whatever ratio they like.

 

[sixty_reefer]

No.

Do you mean that:
If available P is 1000 and N is 16000, all is fine. But if P is 500 and N 16000, there is too little P and everything stops growing?
(I’m using fictitious numbers here)

If yes, then good luck with that.
If not, then who cares about ratios.

Let me put it another way, if you eat an unbalanced meal every day (fastfood high in fat and sugar), according to you you won’t grow fat because your nutrients are limited by protein and fibre being low?

Also Redfield has three parts in his ratio. You skip the C. So what you are calling the Redfield ratio is not it.
You also say to use NO3 as measure for total N. That way you’re missing a ton of N. Especially in an aquarium full of corals that take up ammonia before you’ll see any nitrate.
I could go on and on…

Basically, Redfield would turn over in his grave if he could for the vast misuse of his research in this hobby.

So, yes, forget about the Redfield ratio and keep nutrients available for organisms to take up in whatever ratio they like.

No, I’ve mentioned before that it’s not a tool to set residual Nitrate and Phosphate.
Keeping a parameter at a certain ratio has notting to with limitations. Just a personal choice for each aquarist.

not sure why you mention ammonia, I have clarified at the top that in this particular post I was referring to the limitations in heterotrophic bacteria during carbon dosing I thought that it was obvious that C was the form of carbon being added.

 

[Justfebreezeit]

I'm not exactly sure what your point is. It seems like you keep mentioning bottomed it nutrients for carbon dosing.

As long as one or the other isn't zero they will both go down, knowing the ratio wont help.

You haven't given a real reason why you are so high on knowing and attempting to use it.

 

[ReneReef]

No, I’ve mentioned before that it’s not a tool to set residual Nitrate and Phosphate.
Keeping a parameter at a certain ratio has notting to with limitations. Just a personal choice for each aquarist.

not sure why you mention ammonia, I have clarified at the top that in this particular post I was referring to the limitations in heterotrophic bacteria during carbon dosing I thought that it was obvious that C was the form of carbon being added.

Specifying for heterotrophic bacteria, does not make a difference.

If heterotrophic bacteria live in an environment where P and N are plenty available, it still doesn’t matter if that is in a ratio of 1:16 or not.

Yes, N, P or C can all be limiting bacterial growth. But the ratio between them does not determine that.

In a very simplified environment, for instance if you’re making a growth medium to culture some bacterium you may as well have it contain N, P and C in a certain ratio. Then it still is a convenience, not a necessity.

So, to paraphrase Justfebreezeit, you haven't given a valid reason why knowing and attempting to use it is of any relevance.

 

[sixty_reefer]

It’s debatable, if we were discussing method to lower phosphate using the bacteria it would become relevant or increasing bacteria to feed coral and filter feeders.

Knowing on average that for every 0.01 ppm of phosphates exported from the system will need on average 0.16 ppm to 0.25 ppm of Nitrates available in the water column.

I’m a system with 0.8 ppm phosphate and 1ppm nitrate we could theoretically calculate how much Nitrate would have need to add to the system to reduce 0.8 ppm phosphate to 0.05 ppm phosphate for example.

 

[hart24601]

Could we utilise the Redfield ratio a little better in aquaria?​

Yes, by forgetting about it permanently.

I honestly agree. Too many people messing with their tanks when they would be better served just sticking to a range of values and avoiding bottoming out like has been advocated for decades now.

No comment is going to dissuade the OP as it’s all been said on here before, but the redfield ratio has been a negative overall for many reefers. It is at best useless and at worse misleading people into messing with their tank on a misguided quest.

 

[Hats_]

It’s debatable, if we were discussing method to lower phosphate using the bacteria it would become relevant or increasing bacteria to feed coral and filter feeders.

Knowing on average that for every 0.01 ppm of phosphates exported from the system will need on average 0.16 ppm to 0.25 ppm of Nitrates available in the water column.

I’m a system with 0.8 ppm phosphate and 1ppm nitrate we could theoretically calculate how much Nitrate would have need to add to the system to reduce 0.8 ppm phosphate to 0.05 ppm phosphate for example.

i feel like you're overdoing it. sure if enough information on factors are known you can predict with reasonable accuracy what will happen in x amount of time but whats the point?

you say a certain bacteria will remove a certain amount of nitrate and in a certain rate a certain amount of phosphate, but you don't have only that one type of bacteria in your tank now do you? so I really don't see the point you are trying to make. just make sure nether your nitrates nor your phosphates bottom out or rise drastically and your tank will be perfectly fine