Keith, while this author is certainly well meaning, he is frankly, just wrong.
The Redfield ratio is an atomic ratio
So it's the number of atoms.
Most of the science folks go with mass ratios
but not all.
Folks that do not not know any better confuse the two.
Try this out:
P and N.
See what 16N:1P are in terms of moles/mass
Next see what what 16NO3:1PO4 in terms of moles and mass.
14 g/mol x 16 N atoms = 224
30.97 g/mol x 1 P atom = 30.97
Ratio is now in terms of mass and thwe proper units, the unit that we use(mass/weight): 224/30.97 = 7.2 : 1 N
in terms of mass.
So as you can see, someone is very confused................and it's not me :gw
Now lets try the NO3 and PO4:
62 g/mol NO3 x 16 atoms = 992
94.97 g/mol PO4 x 1 atom = 94.97
If you read the BarrReport, you'll note that most plants have a content of 5:1-10:1 N
in terms of mass.
So while the Redfield ratio is close, it's a little light on the PO4.
Still, his interptation is quite wrong. And his conclusions for algae control are certainly wrong.
I'm not going after him personally, but he's promoting a great deal of errors since many seem to enjoy quoting that site even though it's wrong.
Then these myths get spread all over the place and then I get cranky.
The issue I have is when I see such myth making, I really hate to see it because it means that these myths will persist and I'll end up having to train and explain to a large group what the problems with it are.
If folks have been doing it awhile, they will fight over it. Unfortunately they make assumptions and assume that they have made the right conclusion, but when I test their hypothese, they do not, well...........hold any water.
We can have all sorts of ratios and not one single issue as claimed on that site.
You still likely are meeting some of the needs, if not most of them for the plants, but..............you can certainly improve upon the method and also have a greater degree of flexibility and less fear in your routine.
I've come along and done this type of improvement to PMDD=> EI and the list of parameters/levels and the Excel method etc, then NON CO2 methods, then Marine and CO2 enriched methods.
You have to have those conclusions match observations to make any sense of them, don't you think?
I'm trying to get folks to think and be more critical of such advice, my own included.