Nute calc from Canna stats incorrect!

[payn4school]

I hope someone can answer this, I and I just over looking something simple...I posted this in the organic section first, but its like pullin teeth to get a response over there, ghost town these days. Anyways, here is the problem.

Can someone tell me why canna calc is off by so much when computing hydrolplex soil. Try it your self:

http://www.angelfire.com/cantina/fourtwenty/

The bottle says it has 158ppm phos and 105 ppm k.

Well when you imput the percentages for this in the calc the K is right on at 105 but the fricken P is way off at only 82! thats almost off by half and under which is even worse.

So now I cant trust this damm calc and the lucas ratio is not correct either. I am still experiencing a K deficiency and the P is in much high demand than stated.

Plants are massive but nowhere near flawless. There are definet problems with using the botanicare line, a main one being a calcium and K deficency. I will work through it but my Nute calc HAS GOT TO BE MORE ACCURATE!@#!@#@@!
Any suggestions>>>>????DSFGASDGDFWEQ%R#$QWET^#$%%WB$%YV$%YWG

Sorry, just had to pound on the keys for a sec.

6 weeks

 

[meduser180056]

It's hard to tell from the pic, but those plants look like they are overferted, under heat stress, or suffering from PH problems.

Maybe it's just the lighting, but it looks like you got burnt leaf tips, which usually means overfert.

I tried to input the hydroplex soil numbers into my calc and it came out weird too. Don't know what's up with that?

 

[payn4school]

Thanks for the reply, but no no no, The plants are not overferted, they are fine, very happy, just showing calcium and potassium deficiencies. If it were only as simple as overferting, that would be great, but no its much more complex. Anyways thats not why I posted, I will figure out the cause for the deficiency next time around, IF I can figure out this calculator before then.

 

[ShroomDr]

EDITED I fixed the math, the atomic weight of P was wrong, but the concept was unchanged.


I believe the nute calculator is factoring OUT the Oxygen in the stated P (P2O5) and the manufacturer's label is not.
If you take the atomic weights of each element, (P=31 O=16) and add up the formula P2O5, {P=(31*2) + O=(16*5)=(62)+(80)=142}. Then you take the total atomic weight/total Formula weight = actual P level without counting the O level.

62/142 = 0.437

So when they list 'The Available Phosphate (P2O5) 4% you still need to factor out the atomic weight of O to get the elemental ppm of P

Or at least that was how it was explained to me.
Check out the top link in my signature for some common nutrients i ran though that calculator.

 

[sproutco]

Conversion

Conversion

If the bottle states p2o5 to change to just p multiply by .43

k2o to change to just k multiply by .83

The calculator does this for you and may be the difference in numbers your seeing.

 

[payn4school]

So what should I go by? Do the plants uptake just the P2 or the both does the P2 and O2. I guess what Im saying is which is a true measurement of available P levels for the plant? What about the discrepancy of mg as well?

I just talk to some tech at americanagritech (botanicare) and they said they would get back to me with ppm values for the other pure blend line up that does not list the ppm values. Why is it such a odd question to want to know this stuff. They sound as if they have no comprehension of what in the world anyone would use the ppm values for.. WTF. I bet they wont even call back, sounds like yet another money hungary enterprise devoid of business ethics looking to milk consumers by exploiting the latest growing trend, organics... But hey, I could be wrong.

 

[sproutco]

NO conversion for magnesium unless its an oxide too. Usually not. For p and k you have to pay attention to how they are expressed.

 

[imnotcrazy]

^^^^ yeah it has to do with how much of the "ion" (i think that's what its called) is actually contained in the element used to supply it.

Different choices of elements to supply a given nutrient, K for example, given it the same ammount ie: 1 gram/gallon water could in reality supply totally different amounts of N

 

[Grat3fulh3ad]

I believe the nute calculator is factoring OUT the Oxygen in the stated P (P2O5) and the manufacturer's label is not.
If you take the atomic weights of each element, (P=39 O=16) and add up the formula P2O5, {P=(39*2) + O=(16*5)=(68)+(80)=148}. Then you take the total atomic weight/total Formula weight = actual P level without counting the O level.

68/148 = 0.459

So when they list 'The Available Phosphate (P2O5) 4%'

you need to multiply that by the P ratio to factor out the Oxygen (roughly 1.837)


Or at least that was how it was explained to me.
Check out the top link in my signature for some common nutrients i ran though that caculator.

you are correct, and the nute calc is correct.