How to figure out how much N-P-K is in gallon of water

I'm using foxfarm nutrients, i just want to know how much Nitrogen, Phosphorus, Potassium is in per gallon of water. let say I add 10ml of Tiger Bloom (pic 2) which is 2-8-4 and add 5ml of Big Bloom (pic 1) which is 0-0.5-0.7... What is the N-P-K of the gallon water now

You would have to get the nutrient solution itself tested. Its not as simple as just doing some math with the numbers.

MickyMouseSmokeHouse said:

I'm using foxfarm nutrients, i just want to know how much Nitrogen, Phosphorus, Potassium is in per gallon of water. let say I add 10ml of Tiger Bloom (pic 2) which is 2-8-4 and add 5ml of Big Bloom (pic 1) which is 0-0.5-0.7... What is the N-P-K of the gallon water now

Click to expand...

It’s like food. You have a single bag of cookies that came out of a box. On the back of the packaging it says, “ 12 grams of sugar PER SERVING “. Does that mean that every bag of cookies contains 12 grams of sugar..... If the box the cookies came out of says each single bag of cookies is considered 1 serving, then yes, each single bag has 12 grams of sugar. But if it says 3 bags are considered 1 serving, then you have to divide 3 by 12, therefore each bag has 4 grams of sugar. The reason I gave you this example is because it works the same with the nutrients.

Grow big for example says to use 2-3 teaspoons per gallon of water. Meaning 2-3 teaspoons equate to an NPK RATIO OF 6-4-4 PER GALLON of water. It’s safe to assume that if you cut that dosage in half, your NPK ratio would be 3-2-2. So in summary, the NPK ratios on the front of the bottle are based on teaspoons per gallon of water, not the entire content of the bottle is 6-4-4. I hope that makes sense.

Oh man I hate doing math when I'm all medicated off my ass but I'll have a go.

Seeing as how you're using mls for dosing how about we switch the gallon, (I'm assuming a US gal), to litres so the math is a little easier. A US gal is 3.785L or 3785ml

Assuming the NPK values on the bottles are accurate each ml of the Tiger will have 0.02ml of N, 0.08ml of P and 0.04ml of K.
As you used 10ml then we have 0.2mlN, 0.8mlP and 0.4mlK.
Adding the tiny amounts of P and K, from the Big Bloom, (5x0.00N) + (5x0.005P) + (5x0.007K) = (0N+0.025P+0.035K)

That gives us 0.2mlN into 3785ml = 0.00005284N

0.8025P/3785ml = 0.0002120P

0.4035K/3785ml = 0.0001066K

Rounding off to remove insignificant numbers give an NPK of 0.000053-0.00021-0.00011.

Not a hell of a lot eh. Pretty sure my math is correct. The numbers could still be off if the NPK values are really stuff like calcium nitrate as part of the N value then we have to get into molecular weights of all the elements to get the true values of each and that's beyond my pay grade tonight. lol

One of the best threads you will find on the subject.