Redfield ratio? Red herring!

Not confusing anything, bro. I am continuously referring to molar mass as opposed to the quantity of one mole. It doesn't matter how many units are in one mole, as long as it allows me to refer to the periodic table and get a mean atomic mass per mole, in grams.

Are you arguing that 1mg of Nitrate has the same number of N atoms as 1mg of phoshate has P atoms? I've already demonstrated how that's not the case. It has 1.53x the number of N atoms, and this has implications if you want to calculate your Redfield ratio. That is what this thread is about, nothing more, nothing less.
 
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Noooo :)

All of this was just to demonstrate that phosphate is 1.53x heavier than nitrate. In other words you have that many more N atoms than P atoms if both samples are 1mg. All you need to do is multiply your NO3 mg/l value by 1.53 before comparing to the phosphate mg/l. But you can't assume that 1mg/l = 1ppm for both no3 and po4 because of the different molecular masses. If you have ppm values only then compare them straight up.
 
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Eish...i shouldve went to university...then i would understand.
Im good in selling stuff..so @RocketRooster, u make the test kits and i sell it....lol
 
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Hehehe my man, I couldn't make a dependable test kit if my life depended on it.

I can do the red = sour, blue = swee...err, alkaline thing though? We can take the reefing world by storm! :D

As Albert points out, the test kits on the market are designed for the average bloke, but they lead to misunderstandings when you try being all clever and stuff with your redfields and whatnot. :)
 
OK so I test my NO3 and it reads 24 ppm or mg/L. I convert that to N-No3 and it approximates to 5.5 ppm or mg/L of N

I then test my PO4 and it reads 1 ppm or mg/L I convert that to P-PO4 and it approximates to 0.31 ppm or mg/L of P

So now to work out redfield....

So if I now multiply 0.31 by 3.226 to get it to one, I should also multiply the N 5.5ppm by 3.226 which is 17.743.
Do I now multiply the 17.743 or the 24 by 1.53 to get the ratio in my tank?

So I have a 27.15 : 1 N:p ratio.
 
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You multiply the no3 value. The problem here is that we don't know what is the more accurate reading from the test kit, mg/l or ppm. I'd just go with ppm and be done with it. Whichever way you calculate it, your P won't satisfy your N.
 
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In the links I posted, they say its not a given

4) The basic problem with Redfield ratios is that they are empirical. The ratios were originally derived from measurements of the elemental composition of plankton, and the NO3(-) and PO4(3-) content of seawater from a few stations in the Atlantic, but were subsequently supported by hundreds of independent measurements. Yet there is no known reason why the average N:p ratio of plankton should be 16:1. Why not 6:1? Or 60:1? If one looks at the elemental composition of individual species of phytoplankton grown under nitrogen or phosphorus limitation, the N:p ratio can vary from around 6:1 to 60:1. Redfield understood this problem, but did not try explain it, except to note that the N:p ratio of inorganic nutrients in the ocean interior was an average, and that small-scale variability around the mean was to be expected.

5) Despite many reports that the elemental composition of organisms in a region of the ocean does not conform to Redfield ratios, or that the elemental composition of marine phytoplankton grown in cultures is not 16:1, Redfield's fundamental concept remains valid. It cannot be rationalized by reductionist arguments, nor refuted by anecdotal observations. The fact that the NO(3-):pO4(3-) ratio in the interior of all major ocean basins is remarkably similar to the N:p ratio of plankton is due to the residence times of these two elements in the ocean (roughly 10^(4) years), relative to the ocean's circulation time (roughly 10^(3) years). As the residence times exceed the mixing times by an order of magnitude, it should not be surprising that the NO(3-):pO4(3-) ratios in the ocean interior are remarkably constant.

6) The specific elemental composition that is the Redfield ratio is truly an "emergent" property that reflects the interaction of multiple processes, including the acquisition of the elements by plankton, the formation of new biomass and the remineralization of the biomass by bacteria in the ocean interior, as well as losses of nutrients from the ocean because of burial in the sediments (for example, phosphorus in apatite), or outgassing to the atmosphere (for example, production and loss of N2, due to denitrification).(1-4)
Click to expand...
 
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Yes Dallas I am fully aware. As I am that Si and Fe are also part of the stoichiometry. Or modified one in diatoms. Another herring.

C:Si:N:p:Fe refers 106:15:16:1:0.1-0.001

The point here (my point) is of an aquariust calculating his stoichometry from his professional accurate hobbyist test kit.
 
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We know that test kits are not too accurate, so would it matter? Unless of course you had access to water analysis
 
You know, I love the science (even though it has escaped me, thanks @RocketRooster for reminding me), at the end of the day I think we worry to much in the detail of how things work and forget that things actually work. I have made a concerted effort this year not to chase numbers, but to rather watch my tank, use what I know about how animals behave, looking out for problems, keep my hands out my tank and stop fiddling so much.

I read, with a smile on my face, posts on another american forum (and even on this one sometimes) how we are so worried about how products work, how low must our numbers be, what is the correct way of setting up a tank, cycle time, etc, etc. We lose sight sometimes (I know I do) why we keep marines, why we pay fortunes to be in this hobby, in the words of @Paul B, if it aint fun, why are you doing it?
 
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Carlos this is a very informative thread with loads of views and discussions. Number chasing might not be the ultimate in species keeping today. But I am sure it will be in years to come in the understanding and breeding of the many species we will not be able to collect. After all, it is discussions like these that trigger incite to new ideas and rekindle old ones. All are better for it. It is just IMO that there are always different views and interpretations which makes life so rewarding in discussions like this.
 
Heh, it is rewarding but the ambiguity bothers the hell out of an INTJ type like myself. I've turned it over in my head a thousand times and can't find any holes, but that only makes me second guess it even more. That's the beauty of the scientific method in action, I guess. I can't help but feel that there's something I'm missing, and the funny thing is none of it really matters on a practical level. It's like gardening in a way. Sure, that shrub likes acid soil but it grows anyway despite your clumsy efforts. A tank is much more sensitive, but aquarists have mastered the necessary basics long ago, through trial and discussion like this.

The fact that we're down to counting atoms is actually a humorous and heartening indication of how far you oldtimers have dragged the art of reefkeeping out of the murky depths of cluelessness over the years. :)
 
Rocket, us "old timers" are as passionate as ever. We investigate all avenues and methods. Most are not scientific.

A very interesting thread and I am sure it will continue to be expanded and will most certainaly be discussed and referred to. I got a lot of clarity from it. :thumbup:
 
One thing you can never be accused of is a lack of passion, Keith! I mean, you have drums full of dead live rock taking over your back yard! :)
 
Yes talking about the dead calcareous rock. Would the N and P bound to the organic C change in the redfield ratio compared to when it is in water? :lol:

I am a stickler when it comes to salinity. Some say A salinity is referred to as ppt. Salinity is actually a number and is referred to as S=number not as ppm. I am sure you can prove that by mole calculations and why SI now refer to salinity as a notation of S= and not ppm. Most aquariusts refer to salinity as sg and omit the temperature. So salinity is not always "understood". Salinity, Specific gravity, density and conductivity vary with their different influences and some are confused in their interpretation by the aquariust.

You started this bud....
 
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Damned if I know! :lol:

I would assume Redfield hadn't considered sequestered N and P as part of the biotopes he was sampling. I have another 5 zim dollah though that suspects if you put some dead live rock in a spectrometer you might just actually get something that looks like redfield's ratio. That's just speculation though.

In chemistry, the norms are to aim for working with ideals such as standard pressure at 25'C, etc. What I plan on doing when I get my tank is to make a spreadsheet with salinity/sg etc referenced with temps to help with the inevitable confusion. I have a feeling that bloody tank is gonna cut me down to size in short order! :eek:
 
Be carefully. Most reefers use refractometers which are calibrated to a temp of 20c AKA 20/20 or 20%
Some are referanced to 15.56c andothers to 4c. check out the refractive index variants at the different temperatures.

Most hydrometers are referenced at 25c

This is of course refers to Specific gravity at the reference temperatures.

I assume you understand that salinity does not change by temperature and that sg will change depending on temp.....
 
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