PO4 off the charts~

Re: PO4 off the charts~

Sounds fine then as long as you get the pearling back.
Stop the PO4 dosing, do the water changes, don't obsess about the PO4.

Do obsess about CO2 and routine dosing, do obsess about the pearling of the plants. If you have 2ppm vs 5ppm of PO4, do you think there is much difference? Algae? Plants?

No, not much, but .....the pearling stopping says something more than PO4.........


Regards,
Tom Barr

 

Re: PO4 off the charts~

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

~10:1

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.


Regards,
Tom Barr

 

Re: PO4 off the charts~

As long as you have enoyugh PO4/NO3, the tank should do fine over time.
It's when you really drive the NO3 or PO4 down low is when you have issues.

If the PO4 is say .2ppm or less, the NO3 uptake rate will slow dramatically.

There is a very wide range of NO3 and PO4, anything above say 10ppm for NO3 and 1ppm for PO4 is good for most CO2 enriched tanks.

You do not want to get beyond 40-50ppm or so for NO3 on the upper range(fish health issues where not seen till over 100ppm using KNO3) not beyond 4-6ppm for PO4 since it starts to mess with your CO2 giving you a false positive(shows more CO2 than is really there).

If you do the full EI or slightly less(most tanks are fine with less also or a little more of the PO4 etc), the main issue folks have is the high CO2 demand since that is typically what causes algae issues in EI dosed tanks. 99% of the issue tends to be that if the person has been dosing EI routinely and has most of the tank filled with plants.

Regards,
Tom Barr


Regards,
Tom Barr