translating 20-20-20 (NPK) 1 ounce pr. gallon to ppm - litres

[Martin]

hi

I've been trying to suss out how to translate [topic] directions to something I can use.... and apparently I need your help

I've got a lot of ferts standing about which I use for my tanks... and I thought.. well why not make my own orchid fert as well since I have all the raw ingredients..

so I've been looking at orchid ferts and it seems that 20-20-20 is a good mix..

so now I'm trying to figure out how to mix it..

how do I translate 20-20-20 to something I can measure, weigh, and mix? my mind is severely boggled by this.. and I've done some serious fert calculations for aquarium plants.. but apparently this has me stomped...

I'd like to mix 500ml bottles of the fertilizer..

so please...suppress your snickers ( ) and guide me!

 

[Tom Barr]

What % of the Nitrogen is NH4 and what % is NO3?

 

[Biollante]

I Think This Should Be Okay, If Not...

Hi Martin,

I think I am allowed to answer this. Though I admit, I am dependent on information you publicly provided in the post, which according to the Guru team I am not supposed to use. In addition, I will explain some things you did not directly ask, which again according to the Guru team I am not supposed to offer. :disillusionment:

• I pm’d, in case this is deleted by the Guru team.
  

20-20-20 (NPK) means 20% (or 200,000-ppm) Nitrogen, 20% (or 200,000-ppm) Phosphorous as P[SUB]2[/SUB]O[SUB]5[/SUB] and 20% (or 200,000-ppm) Potassium as K[SUB]2[/SUB]O.

Now here is the tricky part, if it is not all nitrates, then you may have additional problems. Take a close look at the label and see if “N” is further defined.

{The following numbers are from Hydroponic Food Production: A Definitive Guidebook for the Advanced Home Gardener and the Commercial Hydroponic Grower, Sixth Edition, page 66, by Howard M. Resh, except the conversion to PO[SUB]4[/SUB][SUP]3-[/SUP], which I derived from this table. If you would like me to show how these numbers are derived, I will have to do that by pm.}

• Multiply “N” by 4.429 to convert to NO[SUB]3[/SUB][SUP]-[/SUP]
• Multiply “N” by 1.216 to convert to NH[SUB]3[/SUB]
• Multiply “N” by 4.721 to convert to (NH[SUB]4[/SUB])[SUB]2[/SUB]SO[SUB]4[/SUB]
• Multiply “N” by 5.861 to convert to (Ca(NO[SUB]3[/SUB])[SUB]2[/SUB])

• Multiply “P as P[SUB]2[/SUB]O[SUB]5[/SUB]” by 1.34 to convert to PO[SUB]4[/SUB][SUP]3-[/SUP].

• Multiply “K as K[SUB]2[/SUB]O” by 0.830 to convert to K[SUP]+[/SUP].

Since 1-ounce per gallon is 1-part per 128, assuming 1-ounce is the equivalent of 28.349-grams, there are 1000-miligrams per gram, and 1-miligram per liter equals 1-part per million and 1-gallon is the equivalent of 3.785-liters.

• Therefore 1-ounce per gallon equals 7,812.5 parts per million.

Down to cases, if the “N” in the 20-20-20 (NPK) is derived from Nitrate then it is

• 885,800-ppm NO[SUB]3[/SUB][SUP]-[/SUP]
• 268,000-ppm PO[SUB]4[/SUB][SUP]3-[/SUP]
• 166,000-ppm K[SUP]+[/SUP]

Then 30-grams (roundup the ounce) of 20-20-20 (NPK) in a 500-militer solution is

• 26,574-ppm NO[SUB]3[/SUB][SUP]-[/SUP]
• 8,040-ppm PO[SUB]4[/SUB][SUP]3-[/SUP]
• 4,980-ppm K[SUP]+[/SUP]

So, 1-mililiter of the solution would raise 10-gallons of water

• 1.4-ppm NO[SUB]3[/SUB][SUP]-[/SUP]
• 0.42-ppm PO[SUB]4[/SUB][SUP]3-[/SUP]
• 0.26-ppm K[SUP]+[/SUP]

Now on to the other problem, this will probably cause the pompous Guru team to delete this post…:highly_amused:

I have an All Purpose 20-20-20 Jack's Classic JCAP1 that advertises itself for Orchids. The problem is that according to the label the 20% total Nitrogen is 2.1% Nitrate and 17.9% Urea. The problem is the Urea hydrolysis that leads to 46-51% ammonium (NH[SUB]4[/SUB][SUP]-[/SUP]) as ammonium carbonate, which is rather unstable and can decompose to ammonia (NH[SUB]3[/SUB]) and CO[SUB]2[/SUB] resulting in harm to our critters and plants.

I have never tried this, but I suppose in a heavily planted with a light critter load in acidic water you might get away with it.

I would think something like 120-grams Jack's Classic JCAP1 into 300-mililiters distilled water, and then add enough distilled water to make a 500-mililiter solution.

Biollante

 

[Biollante]

Not Trying To Further Aggravate the Guru Team

Hi,

I have had a few questions on deriving these numbers, honest questions are always welcome.

In this example, I simply looked up the conversion factor from a reliable reference book I own, Hydroponic Food Production: A Definitive Guidebook for the Advanced Home Gardener and the Commercial Hydroponic Grower, Sixth Edition, page 66, by Howard M. Resh.

• Which says to multiply “N” by 4.429 to convert to NO[SUB]3[/SUB][SUP]-[/SUP] and of course the inverse,
  • multiply NO[SUB]3[/SUB] by 0.226 to find the amount of N, normally we right this as NO[SUB]3[/SUB][SUP]-[/SUP]-N. Also on page 66 of this source:
• Multiply “N” by 7.221 to find the equivalent amount of KNO[SUB]3[/SUB]
• Or, multiply “KNO[SUB]3[/SUB]” by 0.1385 to find “N” (the inverse of 7.221).

• As a small criticism of Mr. Resh’s arithmetic, the table is a touch precious, given that he rounds off atomic weights, in this example Nitrogen to 14 and nitrate to 62
  
• then returns the answer to 4-deimal places.
  
• (Nitrogen is 14.006272 and Oxygen, 15.99943, so the weight of nitrate is (14.006272 + (3*15.99943)) is 62.004562 and 62.004562 ÷ 14.006272 = 4.42680442, if we wish to be precise.)
  

• Most folks use (14 + (16*3)) ÷ 14 = 4.4 to find the amount of nitrates required to provide a given amount of Nitrogen and
• 1 ÷ 4.4 = 0.23 to find the amount of Nitrogen in nitrates.

The method used to calculate the table is to solve for “x,” setting “x” in terms of element or constituent compound, equal to the atomic weight of the compound.

• Given N = 14; NO[SUB]3[/SUB][SUP]-[/SUP] = 62
• Then 14x = 62
• 14x ÷ 14 = 62 ÷ 14
• x = 4.4

• Given N = 14; KNO[SUB]3[/SUB] = 101.1
• Then 14x = 101.1
• 14x ÷ 14 = 101.1 ÷ 14
• x = 7.22

As you have undoubtedly figured out the way to calculate these on our own is to add the atomic weights of the atoms that make up our compounds, and then divide by the atomic weights of the element or constituent compound we are interested.

• Dividing the atomic weights of the compound by the atomic weights of the constituent elements or compounds and multiplying by 100 gives us the percentage.
  

In the case of KNO[SUB]3[/SUB], we find the atomic weight from the periodic table of the elements or my favorite the unit we assign to these numbers is the gram per mole ([SUP]g[/SUP]∕[SUB]mol[/SUB]):

• K[SUP]+[/SUP] = 39.1-[SUP] g[/SUP]∕[SUB]mol[/SUB]
  
• N[SUP]+[/SUP] = 14-[SUP] g[/SUP]∕[SUB]mol[/SUB]
• O[SUP]2-[/SUP] X 3 = 16 X 3 = 48-[SUP] g[/SUP]∕[SUB]mol[/SUB]
• Therefore KNO[SUB]3[/SUB] = 39.1 [SUP]g[/SUP]∕[SUB]mol[/SUB] K[SUP]+[/SUP]+ 14-[SUP] g[/SUP]∕[SUB]mol[/SUB] N[SUP]+[/SUP] + 48-[SUP] g[/SUP]∕[SUB]mol[/SUB] O[SUP]2-[/SUP] = 101.1-[SUP] g[/SUP]∕[SUB]mol[/SUB] and
  • NO[SUB]3[/SUB][SUP]-[/SUP] = 14-[SUP] g[/SUP]∕[SUB]mol[/SUB] N + 48-[SUP] g[/SUP]∕[SUB]mol[/SUB] O[SUP]2-[/SUP] = 62-[SUP] g[/SUP]∕[SUB]mol[/SUB]
• Therefore:
• ((39.1-[SUP]g[/SUP]∕[SUB]mol[/SUB] K[SUP]+[/SUP])/(101.1-[SUP] g[/SUP]∕[SUB]mol[/SUB] KNO[SUB]3[/SUB]))(100% KNO[SUB]3[/SUB]) = 38.67% K[SUP]+[/SUP]
• ((14-[SUP]g[/SUP]∕[SUB]mol[/SUB] N[SUP]+[/SUP])/(101.1-[SUP] g[/SUP]∕[SUB]mol[/SUB] KNO[SUB]3[/SUB]))(100% KNO[SUB]3[/SUB]) = 13.85% N[SUP]+[/SUP]
• ((62-[SUP]g[/SUP]∕[SUB]mol[/SUB] NO[SUB]3[/SUB][SUP]-[/SUP])/(101.1-[SUP] g[/SUP]∕[SUB]mol[/SUB] KNO[SUB]3[/SUB]))(100% KNO[SUB]3[/SUB]) = 61.33% NO[SUB]3[/SUB][SUP]-[/SUP]
• Obviously this assumes 100% pure KNO[SUB]3[/SUB] accuracy can be increased by substituting the 100% purity of the compound, in this case KNO[SUB]3[/SUB], which for fertilizers should run from about 86-99%.

Biollante

 

[Tug]

I've been asking wet if that other calculator will do just this sort of thing. Still, lost would be the perceptual glory it possesses. All lost in one calculator, a page from "Hydroponic Food Production." Nice reference, Bio.

Guys, guys, hey guys, guys: pssssssssssst: