4:1 potassium to nitrate relationship? - The Planted Tank Forum
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post #1 of 2 (permalink) Old 02-12-2005, 01:10 AM Thread Starter
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4:1 potassium to nitrate relationship?

I saw this quote from Tom Barr and I'm not sure I follow. In regards to dosing extra K in a tank:

"Yes, ample K+ can be supplied via KNO3 exclusively.... you have a ratio of about 4K's for each 1 NO3 you add using KNO3 as far as plant use(4:1)"

I'm not following the 4:1 ratio part of this. Using Chuck Gadd's calculator:

Let's say I add 1/2 TSP of KNO3 to my 50g. That yields about 9.07ppm NO3.

Using the calculator, it shows that when adding 1/2 TSP of KNO3, I am adding 5.73ppm of K.

9.07ppm NO3 and 5.73ppm K.... where's the 4:1 ratio, if any?

Just wondering, since I know some folks don't supplement K in their fert regiment. Right now, I am doing 5ml of "Flourish K" 3x a week on macro day (until I use my Greg Watson K ferts), along with my KNO3 and KHPO4.

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post #2 of 2 (permalink) Old 02-14-2005, 05:03 PM
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Hmmm, that quote from Tom Barr does sound weird. Like you, I use Chuck's calculator, and your 9ppm and 5.7ppm of NO3 and K respectively is how I see his calculator working...and in fact others like Rex Grigg will agree that KNO3 is mostly NO3.

The ONLY thing I can think of is that Tom is talking about the Nitrogen in Nitrate and its ratio to potassium. IE you get 4 potassium atoms for each nitrogen atom.
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