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Help Me Understand Npk Percentages, Full Strength, Etc..

Discussion in 'Nutrients and Fertilizers' started by jguit, Mar 19, 2018.

  1. jguit


    This is more of a curiousity more than anything. Just to get a better understanding of nutrients, etc.

    So for instance, take a fertilzer like Jack'c Classic 20-20-20. I understand that means 20% of each of the macro nutrients. I guess my question is at what weight do you get the 'full' 20-20-20?

    I've been playing with some of the nutrient calculators and trying to understand the ppm's of each of the nutrients at different strengths.

    For instance, take Epsom salt as an example. It's approx 10% Mg and and 13% S. At 1 gram per gallon you'd get approx 26ppm of Mg and 34ppm of S.

    I'm trying to apply this to a powdered fertilizer. I hope i'm explaining myself correctly. haha
    DemonTrich likes this.
  2. Are you trying to calculate what ppm do you get when you add it to your water? Or are you trying to make a solution of 20-20-20 npk to kill the plant?:D I mean when it says 20-20-20 don’t you get the same ratios at every gram?
    jguit likes this.
  3. jguit


    Ha.. I've done a bunch of reading and am pretty sure i understand now. I guess what was confusing me is when someone says 'use at half strength'. Half strength of what?

    I now understand that the NPK numbers represent weight per volume and can calculate ppm and strength based on that.

    The goal is to make solutions of 20-20-20 NPK and supplements (mg and ca) that WON'T kill a plant! :cry:

    I'm pretty sure i have a handle on it now. It just took a few to sink in!
    Quantrill and CrimsonEcho like this.
  4. Well hydro is something different of course i wouldn’t know if you could get a solution as rich as 20-20-20 and not burn them but i grow in amended soil so i wouldn’t know. When you dilute a solution with twice as much water as recomended you get a solution diluted to half of what was suppose to be. I get what you are saying though i think you want to know is the ratio calculated by, for example, number of molecules? In which case some molecules would be bigger and heavier but if you were to calculate by a count of molecules in every given weight the ratio would be the same (?) (not a chemist) but if you were to calculate it by weight because some of the molecules are heavier so there would be less of them by molecule count (i should lay off smoking right now) :D i don’t know if it makes sense?
    Last edited: Mar 21, 2018
  5. All plants in nature use average 12 minerals...nitrogen, calcium, iron, manganese, potassium, phosphorus, magnesium, molybdenum,copper, boron,zinc, sulfur...nitrogen is not considered as a mineral but activator...sea minerals or clay or volcanic ash provide a vast array of minerals, and your fulvic is the electrolytes...all containing nature's full spectrum vits, carbs, aminos, you name it, like's in there...