Understanding NPK values

[GMO]

Hi growers

ive been really interested lately in the idea that we are only engaging part of the information we are given by nutrient bottles and the value of the information given to allow us to cater our feeds to our ideal ratios for the correct stages of growth cycle

my theory is that NPK values are based on a specific % value IE, a 2-4-6 NPK is 2% N - 4% P - 6% K and 88% water. this is somewhat confirmed by bottles which display v/v or w/v, which is explained in the below link from Canna

http://www.canna-uk.com/article_npk

The best indication is given by dissolving equal amounts of both concentrates in a litre of water and measuring the mixes to find the highest level of electrical conductivity.

So with that information in mind, would it be prudent to use the information given to create "our" ideal NPK ratio at the correct times and is this what we have all been doing the whole time without taking note?

i look forward to peoples views

[Bulls]

If you get 3 different bottles of Flower Boosters - lets say A 0-4-10 , B 2-14-15 and C 2-20-22 and dissolve 1 ml of each into 1 L of water obviously the solution with higher EC will be C. Most of them would advertise to use their products at 1 ml per L through flowering even more sometimes. I think using PK booster from early flower often causes salts build up in coco. No mater how much runoff you get, you always do. Simply because the NPK ratio of the boosters doesn't seem to be perfect for the plants needs. On another side - it's hard to get the perfect ratio simply because plants feed diferernly in different environment. It's a lot of factors to consider. I think lower the NPK ratio the better. The highest PK I've used was 13/14 and I find it too strong. You must be very careful and experienced not to burn your plants and stall their growth if you decide to use this exact PK through the entire flowering phase.

[GMO]

no offence, but i think we half missed the point;

as you say 13/14 is too strong. but at what ratios of water

can C 2-20-22 be used at 0.25ml per litre to achieve 0 ish - 5- 6

or B 2-4-10 be used at 0.5ml to acheive 1-2-5

Then taking that information forward adding it to canna coco A+B at 5-4-3 at 1ml. can we create 6-6-8 by adding 0.5ml of 2-4-10

[kbag]

A understanding of NPK values is a good thing but the most important part is reading your plants. I like to grow clones as you learn from previous experience how the plant uptakes these nutrient's and can attempt to dial it in with each grow. As every plant is different growing from seed makes life harder to dial them in. Also you find that some can be pretty unstable making it all the more difficult.
On another point to someone just starting out growing i would advise them to spend extra on the Environment lights fans controllers etc.

[GMO]

Yeah your very right, this is a bit of an advanced train of thought, but

Lemme see if i can put it into a different context that opens up the discussion;

If you have are say 3 weeks into flowering phase, have been feeding 1ml of canna coco A+B at 5-4-3 and 0.5ml Hammerhead PK at 2-4-10. at which point the plant shows signs of yellowing from the bottom up ie N def. we are currently feeding 600mg N, 600mg P and 800mg K. So we decide that we need 200mg more N to counter the def. but we dont want to create a tox of P or K so we up A+B by 0.25ml or 1.25-1-0.66 = 750mg N 700mg P and 866mg K. But if we then further reduce PK by 0.25ml as well or 0.25-1-2.5 = total NPK 725mg N, 650mg P and 616mg K

so by reading the bottles, we dont actually want to reduce PK as it creates a Def from where the plant was feeding happily on K the healthier or atleast closer to the original feed in V/V with just the addition of A+B

does that make sense?

[Bulls]

I am not sure mate it doesn't make sense to me. I never liked numbers and mathematics so I try to avoid them as much as possible.
To be honest I think that's a bit of overthinking and complicating stuff. Without the right equipment you will never be able to make proper analysis of the feed solution you're mixing. I'd say what kbag said.. play it simple and read the plants so far none of them asked me how many mg of what I am feeding them As long as they are happy and feeding then I am happy brother. Choose base nutrients that work for you and choose a PK booster that works for you. That's all you need. The rest is mad science and its way beyond me.

[GMO]

Without the right equipment you will never be able to make proper analysis of the feed solution you're mixing

thats the bit i have to disagree with. we have the information given to us by all nutrient companies which they are very careful not to give us too much info, but we dont know how to use this piece of information.

I really dont see it as over complicating at all. its forming a base understanding of how we build our nutrient feeds. its very important to read the plant, but how do you know what to give without reading the bottles?

[GMO]

Yeah your very right, this is a bit of an advanced train of thought, but

Lemme see if i can put it into a different context that opens up the discussion;

If you have are say 3 weeks into flowering phase, have been feeding 1ml of canna coco A+B at 5-4-3 and 0.5ml Hammerhead PK at 2-4-10. at which point the plant shows signs of yellowing from the bottom up ie N def. we are currently feeding 600mg N, 600mg P and 800mg K. So we decide that we need 200mg more N to counter the def. but we dont want to create a tox of P or K so we up A+B by 0.25ml or 1.25-1-0.66 = 750mg N 700mg P and 866mg K. But if we then further reduce PK by 0.25ml as well or 0.25-1-2.5 = total NPK 725mg N, 650mg P and 616mg K

so by reading the bottles, we dont actually want to reduce PK as it creates a Def from where the plant was feeding happily on K the healthier or atleast closer to the original feed in V/V with just the addition of A+B

does that make sense?

Edit!!! the mg values used should have been in ml as we are talking about liquid feeds and not w/v or weight to volume measures and also would be 0.0 lower than the figure stated i think

Edit edit; values are in mg but as before should be 0.0 lower

[Bulls]

I don't know mate. I am not sure if adding 0.5 ml of some nutrients to 1L of water automatically reduces it's NPK values in half. I belive not to be honest. It will probably reduce them somehow but not that much. Otherwise we all were going to be buying really strong nutes and deluting them with water so they last longer.
Also I don't really think you must be so specific at the ratios. You're saying how would you know how much to give. I guess that's why we have EC meters. Base nutrients have pretty much everything for the plant to grow and you adjust the strength by the EC value. We do have the odd calmag deficiency which we sort out easily by adding calmag at a dose stated on the label. There is now way for you to know exactly how much calmag the plant needs to recover from the deficiency - you just give them until they look good.

[GMO]

if one millilitre of nutrient contains 24 mg (0.024 g) of nitrogen, 100 mg will be obtained in 100/24 = 4.1 ml. To end up with the product I want to use on my plants, a liquid fertiliser with 100 mg of nitrogen, I should dissolve 4.1 ml of fertiliser concentrate in a litre of water. The NPK ratio in this example shows us that we will also be adding 100 mg of phosphate and half that much (50 mg) potassium.

it dilutes or concentrates

its like adding a 200mg ibuprofen to 100ml of water and you have w/v of 2% or 200mg. add a second 200mg and it will have w/v of 400mg, but dilute the 100ml of water with another 100ml and your w/v is 100mg