How Do You Calculate Nutrient Mixtures?

[Buds Buddy]

Hi All,
I'm most likely going to be working in a Cannabis Grow Facility after the 1st of the year. The place is under construction now & I've been in talks with the owners. They've pretty much said I have a job once it opens if I'm still interested.
I'm pretty sure things are done differently in a grow facility then we do things at home. Never the less, Learning more about mixing nutes by N-P-K percentages sounds like it would be helpful.
What I'm doing now is a personal grow at home. All through 8 + weeks of Veg I used Mega Crop only & went up to 4 grams per gallon.
I'm currently at close to 3 weeks into Flower. I'm still feeding 4 gr. per gallon of MC which was all they got the 1st week of Flower. The 2nd week I kept the MC at 4 gr. but added .5 gr. per gal. of Sweet Candy. All is fine. 3rd week I'm now feeding 4 gr. MC & 1 gr. per gal. of Sweet Candy. Now that I'm starting the 4th week of Flower & the pistils are everywhere starting to make buds, I want to add Bud Explosion to the mix. Really not sure how to calculate all of this so I'll post the info in my next post. I think knowing how to calculate these things would be of great help.
Anyway, I'm growing 1-Blueberry, 1- SFV Kush & 1 - OG Pie Breath. They are all in Fox Farms Ocean Forrest in 5 gallon grow bags. I use 3 Mars Hydro TSW 2000 lights (1 for each plant). All bottoms have been stripped & they were all Super Cropped a week ago.
I've been growing almost 4 years now & @Emilya was my mentor (Thanks Emilya). I just never got technical about things till this year. In the past year I've invested in & currently use a Digital Microscope, Light Meter, IR Temp Gun & several pieces of grow equipment that help environmental grow conditions.
This is my 3rd grow using Mega Crop. My 1st grow I only used the MC the entire grow. Buds weren't all that frosty & the weed was OK but not the strength I like it. My 2nd grow I used Terpinator during Flower. I was told I could use as much as 8 ml. per gal. along with the MC by @MrSauga . I was kind of nervous so I only used 1/2 that at 4 ml. per gal. Plants were the frostiest I've ever had & the weed was way better then the 1st grow with MC. I'm smoking it now (Critical 2.0). I'd sure like to know how he calculated this so I can figure out this stuff on my own.
Now the 3rd grow (my current grow) I'm using 4 gr. MC with 1 gr. of Sweet Candy per gal. so far & all seems fine. Actually, leaves are a little on the light green side so I may need to increase MC a little.
Not sure because I'm looking to add Bud Explosion to the MC & SC at this point.
So @Emilya , @MrSauga , @InTheShed , @Pennywise & anyone else with this kind of knowledge ... please join in & help me learn this.
I'll post the N-P-K info for each below. Thanks All !

 

[Buds Buddy]

Here's the Info: Mega Crop 9 - 6 - 17 : (N) Nitrogen 9%
(P) Phosphate 6%
(K) Potash 17%
Other common ingredients: (M) Magnesium 2.3%
(S) Sulfur 1.9%

Sweet Candy 0 - 17 - 28 : (N) 0%
(P) 17%
(K) 28%
(M) 2%
(S) 6%

Bud Explosion 0 - 26 - 37 : (N) 0%
(P) 26%
(K) 37%
(M) 1%
(S) 7%

The way I'm seeing it is I'm not getting enough P & K using straight MC to get maximum results. Bud Explosion P - K numbers are way higher then in MC. Sulfur goes way up too. Only N & M go down. Don't really need much N right now & Cal Mag takes care of M if I see signs I need it.
So how do I go about mixing these things for the best results ?
Bill Nye .... you out there ?
I would also love to know how to go about calculating these things myself. I'm pretty good at math. Just not real familiar with working with chemistry.
Any help is good help .... even if it sends me to a site that has this kind of info.
"Thanks"

 

[The Celt]

Ok so you want to get an understanding of the math, it’s really nothing magical and I will use Mega Crop as an example so it makes it even easier.

So my bag of MC says 9-6-17 which means 9% N, 6% P and 17% K so for every 1g of MC, you have 0.09g (90mg) of N, 60mg P and 170mg of K.

ppm is mg/kg or mg per 1L as 1L of water weighs 1Kg.

Now, you were using 4g per gallon or 4g per 3.78L, so to find the ppm of this mix, take the mg and divide by the litres:

N @ 90mg/g x 4g MC gives 360mg of N which when divided by the litres gives:

360/3.78 = 95.24 ppm

and P = 240/3.78 = 63.5 ppm

and K = 180 ppm

The P is in the form P2O5 and K as K2O

If you want the actual elemental P & K values, then you need to do some chemistry calculations to determine the % of elemental P & K in the forms they are supplied using their respective atomic weights.

 

[Justin Goody]

Your plants look awesome and healthy

No disrespect intended here- if the MC instructions say to feed 6g during flower, why only feed 4?
That’s the first thing @Emilya usually asks people when they talk about feeding 80% etc is Why not feed what the label says?

I ask because I’ve been seeing it so much lately. Lots of folks asking if their yellowing is due to under or overfeeding but they are not even feeding at 100% yet. I feel like people are doing their plants a disservice by not giving at least what is recommended.

I can imagine working in a facility that grows, they would have some sort of plan laid out for nutrient cycles etc. But if they don’t, simply going by manufacturers recommendations is a good place to start until you’ve established a fine tuned system geared toward individual strains.

 

[Emilya Green]

good luck! I am hoping to learn something here along with you!

 

[The Celt]

Although I have only the past few months grow to go by, but I agree with @13goody13

Mega Crop is intended to use the N levels as an indicator as to feed levels and can be increased until signs of stress develop at which point you scale back a bit. The levels will vary according to the plant as no 2 plants are going to be the same.

I have 7 girls, 2 strains in various size containers from 5gal to 22gallon and they have all been getting 6g/gallon MC daily for the past 2 months. These girls are outdoors and the weather here has been phenomenal this year for growing. At 6 grams per gallon, they are getting enough N and more than enough K even in bloom.

 

[Pennywise]

Talk to @InTheShed or @MrSauga

 

[Buds Buddy]

Your plants look awesome and healthy

No disrespect intended here- if the MC instructions say to feed 6g during flower, why only feed 4?
That’s the first thing @Emilya usually asks people when they talk about feeding 80% etc is Why not feed what the label says?

I ask because I’ve been seeing it so much lately. Lots of folks asking if their yellowing is due to under or overfeeding but they are not even feeding at 100% yet. I feel like people are doing their plants a disservice by not giving at least what is recommended.

I can imagine working in a facility that grows, they would have some sort of plan laid out for nutrient cycles etc. But if they don’t, simply going by manufacturers recommendations is a good place to start until you’ve established a fine tuned system geared toward individual strains.

Almost everyone I know starts out with 1/2 the Manufactures Recommendations. Reason for this is because we have gotten toxicities starting out with what they recommend. Most of the time a full gram jump at once is too much. I increase .5 gr at a time. Once I see leaves looking a little on the dark side I quit increasing to prevent a toxicity. Once I see the leaves get a lighter green I know they want more. I learned a long time ago not to follow the recommendations to a tee. They could tell you to increase strength at week 5 yet your plant is dark green. Each strain is different & can only handle so much. Therefore, leaf color is the key to feeding.

 

[Buds Buddy]

Ok so you want to get an understanding of the math, it’s really nothing magical and I will use Mega Crop as an example so it makes it even easier.

So my bag of MC says 9-6-17 which means 9% N, 6% P and 17% K so for every 1g of MC, you have 0.09g (90mg) of N, 60mg P and 170mg of K.

ppm is mg/kg or mg per 1L as 1L of water weighs 1Kg.

Now, you were using 4g per gallon or 4g per 3.78L, so to find the ppm of this mix, take the mg and divide by the litres:

N @ 90mg/g x 4g MC gives 360mg of N which when divided by the litres gives:

360/3.78 = 95.24 ppm

and P = 240/3.78 = 63.5 ppm

and K = 180 ppm

The P is in the form P2O5 and K as K2O

If you want the actual elemental P & K values, then you need to do some chemistry calculations to determine the % of elemental P & K in the forms they are supplied using their respective atomic weights.

Thanks, I'll copy & save this.

 

[TorturedSoul]

Might want to consider making your own cannabis nutrients from bulk dry components. That would save you a LOT of money.

See:

Making Your Own Nutrient Concentrates

This is my attempt to compile and condense all of the information I've collected from other grower sites and share it here on 420 in hopes of generating more feedback and ultimately learning more myself. I grew with General Hydroponics for years, but could never seem to nail down a perfect feed...

www.420magazine.com

 

[InTheShed]

I use a spreadsheet created by a member here that includes a number of nutrient lines (others have done similar) that will let you calculate what you're feeding your plants. I did a post on it recently in Pink's thread here!

 

[mrking]

I use a spreadsheet created by a member here that includes a number of nutrient lines (others have done similar) that will let you calculate what you're feeding your plants. I did a post on it recently in Pink's thread here!

How does one get ahold of this spreadsheet?

 

[Buds Buddy]

Might want to consider making your own cannabis nutrients from bulk dry components. That would save you a LOT of money.

See:

Making Your Own Nutrient Concentrates

This is my attempt to compile and condense all of the information I've collected from other grower sites and share it here on 420 in hopes of generating more feedback and ultimately learning more myself. I grew with General Hydroponics for years, but could never seem to nail down a perfect feed...

www.420magazine.com

I wouldn't doubt if they make their own in a grow facility so it's something I will take a look at.

 

[InTheShed]

The member who created it hasn't been online recently but I'm sure he'll return soon. I don't feel comfortable redistributing his work without permission, and no matter what, it would have to be via PM since we are not allowed to post links to google sheets here.

I'll ask and see how he feels about me sending it into the wild and I'll report back when I hear.

 

[MrSauga]

I'd sure like to know how he calculated this so I can figure out this stuff on my own.

It's all about understanding ratios and nutrient ppm levels in plants. Go outside those ratios and expect the plant to react negatively. Even then we can only guess since ratios are based on tissue samples. It would be assumed that we are controlling those ppm levels through the nutes, but does 200 ppm of K in nutrient form equate to 200 ppm of K in the tissue sample?
Potassium, Ca and Mg appear to be needed in larger quantities in comparison to other floriculture species. Increasing the levels of K, contrary to the Mulder's Chart, decreases the availability of Ca and/or Mg. Provide K, Ca and Mg in a 41 ratio avoids antagonisms. The image below shows how increasing K effects the uptake of Ca and Mg.

Poinsettias need around 200 ppm K to 100 ppm Ca to 50 ppm Mg and since cannabis is similar in that it's a short-day plant it's a good rule to follow.

So now you know that part. The next is understanding how much P a plant needs. A graduate student, Josh Henry, worked on optimizing P fertilization rates for his master’s degree thesis at NCSU. Plants require a baseline level of P to grow adequately. For a continuous fertilization program for plants grown in a soilless substrate, the target concentration is between 8 ppm and 15 ppm of P. Providing levels below that will result in less plant growth, while concentrations above that level provide little benefit.
Since there really is no data on P needs for cannabis increasing those levels from 15 ppm to 25 ppm would be an acceptable range. Higher than that and you risk antagonisms or stimulations. North Carolina State University has begun an experiment looking into optimal P rates supplied at a constant level throughout the cannabis crop cycle and most likely will refine those recommendations in the near future.
The image below shows the response of Alternanthera to increasing concentrations of P from 0, 5, 10, 20 and 40 ppm (left to right).

You can see the growth slowed after 10 ppm and basically stopped after 20 ppm. Phosphorus is also the primary contributor to plant stretch. Too much P will lead to excessive internode elongation and tall plants. That’s why it’s important to limit excessive P in grow applications. We often hear about growers wanting to add bloom enhancers and yet the plants don't want it and ultimately it leads to deficiencies because of overuse. The next image shows the nutrients that are from a tissue sample of a plant. Again notice the percentages and acceptable ranges.

You can use the following ratios as a guide to growing cannabis:
10 parts Nitrogen
1 to 2 parts Phosphorus
10 parts Potassium
5 parts Calcium
2 to 3 parts Magnesium
1 to 3 parts Sulfur
The micronutrients are important and most can be found in tap water(get a water report) but if you don't use it then of course you need to add those which most ferts carry enough of anyhow.

The nitrogen should be mainly in the nitrate form as it provides more compact and controlled growth. More extensive leaf and stem growth occurs with ammoniacal and urea nitrogen. In general, to avoid excessive stretching and oversized leaves, more than 60 percent of the nitrogen provided to plants should be in the nitrate form. Ideally 70 to 80 percent as this will provide a moderate growth response and avoid overly large cannabis plants.

I'm sure I bored many here but there's more that is readily available online to look up. Is it a science to figure it all out? Sure it is and that's why people spend years understanding it all. But if you try and follow the basics you'll do fine. Hopefully that's enough to get you on your way.

 

[TorturedSoul]

I wouldn't doubt if they make their own in a grow facility so it's something I will take a look at.

If you do decide to go that route, Custom Hydro Nutrients (dot com) sells bulk dry components in one-, four-, twenty- and forty-pound reclosable plastic containers, fifty-pound bags, and full pallets. They should have every element/mineral/etc. you need to grow any kind of plant, sprout to harvest. You might find cheaper prices if you're willing to hunt around for individual items (IDK), but that website will at least give you an idea about what kind of stuff is available.

You could probably find anywhere from several to many nutrient recipes via web search. This isn't really a new thing - I was browsing in my local library way back in the early- or mid-1980s and saw a book that had hydroponic nutrient solution recipes (although not specifically for cannabis, lol), and its copyright date was 1972, if I remember correctly. Went back later to borrow the book after I'd found a place to set up an indoor grow (was just a young teenager, and Mom & Dad would have kicked my ass AND called the cops if I'd tried to do an indoor cannabis garden in their house) and it had been stolen .

 

[The Celt]

Awesome info @MrSauga

 

[InTheShed]

It's all about understanding ratios and nutrient ppm levels in plants...

Millwright you say?

 

[MrSauga]

Awesome info @MrSauga

Thanks Celt!

Millwright you say?

I try not to advertise that.

 

[MochaBud]

Wow, I got tired just reading what y'all are doing here too much work for this old man, not to mention MATH man the last time I did addition I ended up with a cat, a FUCKING cat...'kinda like "John Wick" a fucking pencil'

No seriously though I recently started using MC in my FFOF with fantastic results, and I'm feeding at full strength, but, I only feed every third watering, and that's not to mention that I have 10 strains going ...but I'm lazy, I don't write or mark anything down, I don't PH my water or nutrients, but I do talk really sweet to them while I'm in there