Question on Redfield Ratio

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Snoopdog

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So I am looking at this chart. I have a nitrate of 10, am I reading this right that to have a desirable ratio of 16 to 1 you would need your phosphate at 1? I struggle to get my phosphate at .03

Also most threads I read people seem to want their phosphate at .02 or .03 and nitrates at 10. That seems way off from this chart as something desirable. Yes I know every tank and condition is different, I am just wondering from pure curiosity.

 
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HuduVudu

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So I am looking at this chart. I have a nitrate of 10, am I reading this right that to have a desirable ratio of 16 to 1 you would need your phosphate at 1? I struggle to get my phosphate at .03

Also most threads I read people seem to want their phosphate at .02 or .03 and nitrates at 10. That seems way off from this chart as something desirable. Yes I know every tank and condition is different, I am just wondering from pure curiosity.

Be careful with calculated numbers you calculate may not have the ability to actually test for or even achieve the number that you desire. There is an old saying ... "Calculate with a calculator, measure with a tape measure, cut with a chain saw."

Edit: Looked a bit more carefully at the chart. If you have 10 nitrate you want to shoot for betweenn 1 - 1.5 mg/l phosphate.
 
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Snoopdog

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Be careful with calculated numbers you calculate may not have the ability to actually test for or even achieve the number that you desire. There is an old saying ... "Calculate with a calculator, measure with a tape measure, cut with a chain saw."

Edit: Looked a bit more carefully at the chart. If you have 10 nitrate you want to shoot for betweenn 1 - 1.5 mg/l phosphate.

I saw that too. That seems high for 10 nitrate, just saying.
 

HuduVudu

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@Snoopdog it doesn't really seem that high to me. I think you still have vestiges of the 0 nutrient philosophy.

Phosphates and nitrates are just fertilizer for plants. I don't think any more about them when I add miracle grow to my plants than I do when I feed my LPS extra to keep my nutrients up. Plants gotta eat and this is part of the way they do it. :)
 
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Snoopdog

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@Snoopdog it doesn't really seem that high to me. I think you still have vestiges of the 0 nutrient philosophy.

Phosphates and nitrates are just fertilizer for plants. I don't think any more about them when I add miracle grow to my plants than I do when I feed my LPS extra to keep my nutrients up. Plants gotta eat and this is part of the way they do it. :)

Maybe not. Back 10 years ago when we kept reefs phosphates were a dirty word.
 

Randy Holmes-Farley

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So I am looking at this chart. I have a nitrate of 10, am I reading this right that to have a desirable ratio of 16 to 1 you would need your phosphate at 1? I struggle to get my phosphate at .03

Also most threads I read people seem to want their phosphate at .02 or .03 and nitrates at 10. That seems way off from this chart as something desirable. Yes I know every tank and condition is different, I am just wondering from pure curiosity.


No, one should not read the Redfield ratio as a way to set target levels. It makes no sense to use it that way.

IMO, they should be independently targeted to appropriate levels . Just because one is too hight or too low is not a reason for the other to likewise be too high or too low.

Nitrate at 10 ppm is fine, as is phosphate at 0.02-0.03 ppm. Higher phosphate can be OK. Higher than normal is better than lower than normal.
 
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Snoopdog

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No, one should not read the Redfield ratio as a way to set target levels. It makes no sense to use it that way.

IMO, they should be independently targeted to appropriate levels . Just because one is too hight or too low is not a reason for the other to likewise be too high or too low.

Nitrate at 10 ppm is fine, as is phosphate at 0.02-0.03 ppm. Higher phosphate can be OK. Higher than normal is better than lower than normal.

At my current coral feeding schedule, which is twice a week I can finally maintain phosphates at .03
 
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Snoopdog

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For his 1934 paper, Alfred Redfield analyzed nitrate and phosphate data for the Atlantic, Indian, Pacific oceans and Barents Sea.[1] As a Harvard physiologist, Redfield participated in several voyages on board the research vessel Atlantis, analyzing data for C, N, and P content in marine plankton, and referenced data collected by other researchers as early as 1898.

Redfield’s analysis of the empirical data led to him to discover that across and within the three oceans and Barents Sea, seawater had an N:p atomic ratio near 20:1 (later corrected to 16:1), and was very similar to the average N:p of phytoplankton.

 
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creativeballance

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So...hypothetically...if I dose phytoplankton exclusively, it should "set" my tank to this Redfield ratio?

And does this ratio discourage algae growth because of competition from plankton, or is there some other mechanism that has been explained?
 

flampton

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The Redfield ratio has nothing to do with anything we do in a reef tank. It's just a fun anomaly that plankton and the deep ocean have similar carbon:nitrogen: phosphate ratio. Just as with any living thing the ratios of nutrients consumed does not equal the ratio within the living mass. And furthermore if you really wanted to do the Redfield ratio you need to add organic carbon to 'complete' the ratio. This would be very bad, so don't do it ;)
 

Randy Holmes-Farley

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So...hypothetically...if I dose phytoplankton exclusively, it should "set" my tank to this Redfield ratio?

And does this ratio discourage algae growth because of competition from plankton, or is there some other mechanism that has been explained?

No. Adding N and P in the Redfield ratio (as is roughly the case with most foods that do not include bones) does not result in the same ratio in the tank as they get used by many different processes, some of which use N and P independently.
 
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