understanding the 'NPK% in bottled nutrients for a better understanding of plant nutrition

kaydeezee said:

hello RIU

im a hobby grower that's obsessed with every aspect of Indoor Mj farming and would like some insight into what wee growers are feeding our precious plants.

ive been growing in coco coir for the past 2yrs and for the most part had reasonably ok results however, my main problems have included..
(1) calcium/magnesium issues in mid to late veg & sometimes in mid flower?

(2) too much nitrogen in late flower?

(3) no taste or flavour after harvest?

(4) poor trichome development?

ive always yielded on the high side of 0.5gpw using hps/mh & cheap led at times but always the same results?

i have spent time making sure my environment is ideal for plant growth and temps&HM are for the most part under controll constantly,

my understanding of the enviroment is ok so now i would like to learn about what it is im feeding my plants because ' im sure the reason for my tasteless/weak smoke is the nutrition my plant get from day 1?

im using these form the well respected people at general hydroponics (europe)

GHE flora coco (eorope) grow&bloom with added + 5%Ca & +3%Mg
GHE cocotek pk coco coir 75/25% perlite

i start my seedlings&clones in Rapid rooters then transplant into 500ml pots then 2L pots then finally 11L pots

watering/feed every coupe days when plants are young always ph 5.8 and always 75% 600ppm 1.2EC max nutrient strength since i never use 1000w bulbs and don't produce the high PAR needed for full strength feeding?

so, how do i work out what the percentages on the bottles are as a individual PPM?

on the GHE bottles it states that it has..

(GROW) N.P.K 4-0-5
4.2% NITROGEN.. 0.006% BORON..
5% POTASIUM.. 0.05% MANGANESE.
5% CALCIUM.. 0.007% COPPER.
0.1% IRON.. 0.015% ZINK.

(BLOOM) N.P.K 1-6-4
1% NITROGEN. 0.015% BORON..
6% PHOSPHORUS. 0.005% MANGANESE..
4% POTASIUM. 0.003% COPPER..
3% MAGNESIUM. 0.012% IRON..
5% SULFER. 0.004% ZINK..
0.0015% MOLYBDENUM..

how do i work out the % into ppm is there a formula a can follow to provide this information?

im using RO water EC 0.1/[email protected]=000/[email protected]=029

im using the recommended ratio of 2ml/L grow 1ml/L bloom 2-1 at 75% strength by adding the 2-1 to 1250ml RO water instead of 1000ml RO water to achieve the 75% strength feed but ' i think in doing so i have lessened the amount of Ca% and in doing so have caused a Ca deficiency?

im growing 3x strains all in the same space with all the same ingredients and noticing similar issues so it must be the weaker nutrient level im feeding the girls?

strains are..
RQS hulkberry (aka) bruce banner #3 pheno . aparently lol
RQS royal AK
clone only EXO cheese

group shot View attachment 4183283

cheese clone
View attachment 4183287

royal ak leaf deficiency
View attachment 4183284 View attachment 4183286 View attachment 4183289

any help! on the issues im having please share guys and happy growing

Click to expand...

“im using RO water EC 0.1/[email protected]=000/[email protected]=029”

Click to expand...

Michael Huntherz said:

There is a lot to this question. You need to do some basic research on EC to ppm conversion scales, which are different in the US and Europe. Your instruments will read differently than ours, when reading ppm rather than EC (usually in S/m3) so I think we will have some confusuion due to language difficulties. I can’t really understand your post easily.
Can you break this down for us, it makes no sense to me, maybe put it on separate lines and expicitly state in whole words what the numbers are supposed to be telling us?


I can’t make sense of that, and it makes me think you are overthinking all of this or maybe you are headed in the wrong direction.

You use RO. Cool.
Take a liter of RO and measure the EC.
Take a milliliter of your GH product and add it to the water, then measure it again. Subtract the starting EC from the final EC, then if you wish you may convert to ppm using whatever scale you prefer, in Europe you would typically multiply your EC in S/m^3 by 700. You first need to take these measurements so you can better understand what’s in the bottle, which is information you must have to answer the questions you have asked.

You can then start to learn how calculate elemental ppm, which may or may not be different than the numbers on your product label, since tose labels have different requirements in every country and other jurisdictions often have even more specific regulations. We need to know the chemical sources for each nutrient, most of your phosphorus probably comes from p2o5, so you have a conversion factor by molar mass to elemental P for that source. Nitrate based nitrogen has a different conversion factor than ammoniacal nitrogen. You have a lot of reading to do. Get away from the cannabis forums and go read about general agriculture and fertilizer and how to understand the labels.

Click to expand...

Kami Samurai said:

Use the hydro buddy app. Log in you nutrient and it will tell you ppm of each element. As well you can use it to log your entire regimen and use it to hit certain ratio e.g. 1-2-1/ 3-1-4/ 1-1-2

Click to expand...

kaydeezee said:

how do i work out the % into ppm is there a formula a can follow to provide this information?

Click to expand...

pollen205 said:

I have same problem with same spots on Leaf and really try to figure IT out what is that? Natural pigment or defficiency?

Click to expand...