Nutrient ratios / elemental concentration

Indoor Growing
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Hey people,

this has been bothering me very much lately.

I look at analysis tables of nutrients, say Jack’s Professional, Yara or Haifa. The nutrient compositions are expressed in 3 numbers. For example 20-20-20. We call this N-P-K composition or N-P-K ratios.

These numbers refer to percentage of total weight.

My BIG question is: Why is percentage of P2O5 and K2O given rather than that of elemental P and elemental K??? After all percentage of elemental N is given too!

P2O5 consists of 44% elemental Phosphorus.
K20 is 83% elemental Potassium.

Wouldn’t that make Jack’s 20-20-20 general purpose a 20 - 8.8 - 16.6?
20-20-20 seems like a 1-1-1 ratio but isn’t it actually a 2.3 - 1 - 1.9 ??

After all, when we talk about concentration of nutrient solution we use PPMs of elemental forms of P and K and everything else. We wouldn’t talk about so and so much PPM of P2O5 or K2O.

Please somebody help me get a grasp of this. Would be much appreciated!

G

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Techno info…

https://manicbotanix.com/establishing-ppm-in-solution-from-nutrient-labels/

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@GramTorino I love you man! For real haha Your post is no bullshit, no chitchat, not wasting syllables, straight to the point and you hit the bull’s eye. You made my day without even knowing it! Thanks! What a wonderful website! This is pure gold.

So I was actually on to something with this NPK madness after all…

This thread can be closed now :joy:

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Glad it’s of help. I’m guilty of short posts, but always positive vibes intended.

Fyi.
I use this angel calc dealio to breakdown % to ppm. Bottom of the page.

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