Lefthand's Synthetics from Scratch

Advanced Techniques
143

Synthetics not from scratch

I’m going to make a more lengthy answer to your question, because it’s more complicated than just NPK ratios. I’m glad you asked it and are interested in experimenting as I am. I am learning a lot of things about nutrient solutions this year as you can see from this pretty lengthy thread, and I think I am at a point where I can explain some things that should give you guidance.

I’m calling this ‘not from scratch’ because if you’re using a premixed formula like 5-12-26, then you have to temper your expectations about what you can or should do with it.

The main thing is that you cannot use it in arbitrary amounts. Jacks specifies like 3.7g per gallon, and you can probably get away with using a little more or a little less, but I wouldn’t stray too far from this number. The reason for this is something people don’t often talk about – micronutrients.

The premix has all the micronutrients included, and if you use different amounts than recommended, you will not have the correct amount of them in your feeds. Micronutrients are essential to plant growth, and also immobile! That means your plant has a limited ability to take them from a different part of the plant. So they must be supplied adequately for pretty much the whole grow. If you use less than recommended amounts of 5-12-26, then you will get less than recommended amounts of micronutrients, and then you are unlikely to have an optimal fertilizer for growth.

So the bottom line is that you should consider this to be a pretty fixed amount per gallon, except for maybe the first and last few weeks of the entire plant cycle, when nutrient demands are fairly low.

What this means is that you have 3.7g of a fairly large number ‘26’ for potassium. You will never get to a 3:1:1 ratio in veg, and probably not a 1:3:2 ratio in early flower. You don’t really need to, and really, those ratios are somewhat meaningless on their own. There are 3 main cations (K, Ca and Mg) and 3 main anions (NO3, PO4 and SO4), and NKP only addresses half of them. There’s actually 4 main cations if you include NH4, which shouldn’t be overlooked either. Also, it doesn’t specify EC/ppm of the solution which is also important.

Given that we already know that we need to use around 3.7g of 5-12-26, we should be asking what else can we do to adjust the nutrient solution at different growth stages.

  1. We can alter the other salts to change anion ratios – so we can trade calcium nitrate for something else, or epsom for something else.
  2. We can raise the EC by adding more ‘stuff’

And those are probably the only real viable options, without having a whole cabinet of micronutrients and other things to fix it.

I think option 1 is usually pretty safe, and I would start there. The main things I think you can do is change the anion ratios – ie trading sulfur into phosphorus or nitrogen, or trading nitrogen into sulfur. In general, I feel the formula can use more a little more nitrogen and phosphorus in veg and until the completion of stretch. You can sub magnesium nitrate and magnesium phosphate to accomplish this. In late flower, you may want less nitrogen so you can sub calcium nitrate for calcium sulfate (solution grade) or even calcium chloride.

Magnesium nitrate has a similar % of magnesium to epsom, so you can use it in equal parts as you would epsom. Calcium sulfate has slightly more calcium than calcium nitrate (23% vs 19%), so you could probably use it in equal parts as well or 19 divided by 23 times the amount you used for calcium nitrate if you wanted to be more exact. Calcium chloride is 34% calcium, so if you wanted to remove 0.5g of calcium nitrate you could substitute 19/34 * 0.5 = 0.28g of calcium chloride, etc. Making substitutions is easy without having to use a nutrient calculator.

If you decide to try option 2, it should be done more carefully. Changing the ratios of the cations (K, Ca and Mg) can be trickier and more difficult to understand, since all 3 are important. With the anions, you have sulfur, which plants are tolerant to over a very wide range; however the cations are all very essential in narrower ranges and will inhibit each other. So be careful to make these adjustments modestly. I would probably not recommend adding more than about 0.5g of anything extra without checking hydrobuddy or really fleshing out what all is going on with your other cations.

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Definitely. I recommend hydrobuddy. You have to tinker with it a bit before it makes sense, but once you do, it’ll be your best buddy.

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Good stuff. Very true. One of the cheapest things you can do for your grow.

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How do you take that and figure out how much potassium (for example) you’re getting? Do you just multiply 26 by the 3.7? That would only work if that meant 26 per gram/gallon. And even then the answer would mean what? 96.2 what/gallon?

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image

First thing to know is that NPK in the US is given as N, P2O5 and K2O. If you want to get ppm of K, you need to use a conversion factor 0.83.

Next thing you need to know is that ppm is the same as mg/L. So now you just need to do the conversion from NPK and g/gal into mg/L.

26 = 26% K2O = 0.83 * 26 = 21.58% K

We use 3.7g/gal, and 21.58% is K, so 3.7 g/gal * 0.2158 = 0.798 g/gal (ie 0.798 grams of K per gallon)

Now convert g/gal into mg/L (ie ppm)
0.798g/gal * 1000mg/g * 0.264 gal/L = 210.7 ppm

Here’s hydrobuddy:
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Nice!

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I’m going to have to download that damn app :joy: thank you @lefthandseeds

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Can u guys show me the icon for hydro buddy and the version? I’m trying to download it but it’s a few different places and I don’t want a virus lol just want to make sure I’m downloading the right one.

Nevermind, I got it. Now I just have to figure out how to use it lol

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It’s not super intuitive, but it is 100% worth spending the time to learn. Once you know how to use it, it is a great help to analyzing or changing formulas.

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@lefthandseeds is the man. He has some great project going on. His numbers add up. I would take his help.

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I’m trying. I downloaded the app but can’t figure out how to use it. I’ll have to wait til I have the time to sit down and focus on it. Maybe find a tutorial :woman_shrugging: They need to make a hydro4dummies app :crazy_face:

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Don’t say that. Lol. He will be around soon.

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There’s some tutorials on the YouTube’s that explain hydro buddy in depth.

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Hi lefthandseeds

please have a look at my formula(2) see if i can improve
i grow perpetual on mapito(homemade mix) in 0,5 liter pots 150 to 160 under a 300w diy brideglux led
they are in sets of +/-30 pots 2 weeks apart(every 2 weeks a new set)
i water everyday flood and drain (recirculating)and have a 60liter or 100l tank make fresh every week
i have made a formula with peters combi sol (6-18-36+3mgo+te) +peters bloom (10-30-20+2mgo+te) + mag.sulfat + yara kristalon Calciumnitrat (15,5%,26%)

my water is 0,6 ec and i add 1,3-1,6ec of my mix for a total of +/- 2,0 ec ph is 5,5- 6,5

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in an other formula i use yara kristalon orange(6-12-36+3+8) +peters bloom+ magsulf +calciunitrat
i use it with bigger pots (mapito) and under hid lamps
in my small pots they stretch to much with this formula

2022-01-16 20_31_18-Window
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And as PH down i use sulfuric acid

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I don’t understand why jacks has so much nitrogen in the part a. Especially since you get so much with part b.

I see everywhere to take nitrogen completely out toward the end of flowering. It worked great with gh flora trio. But here, even if you only use part a toward the end, N and P are so close to each other. It’s almost a 1-1-4.5 ratio. Instead of worrying about a potassium booster, why not phosphorus? Some people swear by 3-1-2 veg and 1-3-2 or 1-2-3 for flower. Veg seems right but anyway you work the numbers, you just can’t get flower ratio right. Not without adding more “stuff” to the mix. Or am I looking at it wrong? A lot of people just use the same ratio of jacks all throughout the cycle. I don’t get it unless they’re manipulating what the plant uptakes by changing ph? I’m in coco so I really would like to understand but it aggravates me and makes my head hurt :sweat_smile:

I was really wanting a simple way to feed them but I still want to get the most out of them too. The most I’ve ever harvested off of one plant was 6.5 oz (auto in 5gal coco/perlite, went 90+ days) and I only used gh bloom the last 7-14 days before flush. I think its 0-5-4?

My last jacks run I got 10.5oz out of 2 autos (same strain as the other although I know there are other factors) in 3gal coco/perlite 90+ days. But it didn’t fade like the other one. Like there was still a lot of nitrogen in there. Idk.

This run w the blackstrap auto (which is huge to say the least) I may try to go straight part a for the last couple weeks. I’ve already dropped the Epsom salts (as per your recommendation) from 1g to .25g per gallon the last week or so with no I’ll effects- that I can SEE, that is. And since part b is all nitrogen maybe it will at least help? Hell idk… it’s all so confusing. They should just really come out w their own mixes specifically made for cannabis. Bc I do love the simplicity and price. But they don’t need nitrogen in both parts. That way u can have more wiggle room late into flower.

Unless you tell me I’m dead wrong. I know the immobile nutrients are still a cause for concern too. But for the sake of at least getting the npk down, I didn’t even bring it up. I still don’t fully understand it all. And how each part effects the other. Not to the depth you guys do!! Ughhhh. (Insert emoji pulling her hair out)

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It’s because part A is just calcium nitrate. Cannabis likes a pretty good amount of calcium, especially if you’re growing in coco. If you want to reduce nitrogen while using Jacks, I think the most viable options are:

  1. reduce part A and add calcium sulfate
  2. reduce part A and add calcium chloride
  3. switch part A and use pure cal or cal prime instead

All of these are good options to get reduced N. #3 will essentially reduce N by removing NH4 completely, which may or may not be beneficial.

Potassium is a cation and phosphorous is an anion. That means you can adjust them completely independently if you wish. I think phosphorus and nitrogen are most effectively used together in veg and early bloom, when you want the plant to grow stem, leaf and bud tissues the most. Late in flower, you can choose how you want your plant to grow.

For the biggest yields, keeping high N and P is best. For the highest cannabinoid concentration, low N is best, and I think lower P is likely to have a similar effect. Highest cannabinoid concentrations and highest yields do not occur together, because yield is primarily a function of bud size (as plant tissues). This has the effect of diluting cannabinoid concentrations by spreading resin out on a larger surface.

However, if you are primarily making extract, highest yields and highest total cannabinoid yield do occur together.

There is an extremely wide range of NPK that work fine. But if you don’t have a goal for choosing your ratios, then swearing by one thing or another is meaningless. This is why dozens of commercial nutrients come in with different numbers and can still all work. NPK are all mobile nutrients anyway, so there are many ratios that are tolerable without showing signs on the leaves for many weeks.

Secondly, the reason why it doesn’t make sense is that there is not one NPK ratio that works best for all strains. If you only grow commercial polyhybrids that are selected to be highly tolerant of strong nutrient concentrations, then you can get away with a much larger margin of error for any ratio you choose, simply by using more of everything.

Third, Ca and Mg are extremely important to cannabis. I don’t find any discussion of NPK ratios that exclude NH4 concentrations, Ca and Mg, grow media and water type that it’s used with to be very valuable. If you focus on someone else’s opinion of NPK ratios, but ignore the rest of the equation, then there’s no point in modifying the formulas at all. You can derive virtually any ratio of NPK you want with a combination of ammonium nitrate, ammonium phosphate, potassium phosphate and potassium sulfate, but if you only use those things your plants will probably die. Everything else is important. It would be better to forget NPK ratios ever existed and focus on cation (+) (NH4, K, Ca and Mg) and anion (-) (N, P, S) ratios instead, because at least you would have a more complete picture. I dare say that NPK is useful for outdoor soil only, because most of the other stuff is already sufficiently in the ground… but even that is questionable.

You should think about your ratio of cations you want, and then the ratio of anions you want, and then figure out how to get there. A salt is a cation ionically bound to an anion, and you can pick almost any combination you want. Eg. potassium and sulfur (potassium sulfate), potassium and nitrogen (potassium nitrate), potassium and phosphorus (potassium phosphate)… and the same for pretty much everything else, with the exception of calcium and phosphorus (calcium phosphate), which is not soluble in water.

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I thought part A was 5-12-25

So I was thinking why have the 5 of nitrogen in part a when part b has 15-0-0.

All the other stuff, I didn’t really want to buy a ton of additives. :sob: so I think I’ll stick to reg jacks? I have jacks part a, b, and epsom along with the gh flora trio. What would be the best way to manipulate just those things for flowering?

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Oh, you could be right. I can’t remember exactly which they call A and B. Well the “5” in the 5-12-26 probably comes from potassium nitrate. Nitrogen is generally more useful than sulfur, which their formula already has an excess of. Plus it is mimicking a general purpose 5-11-26 hydroponic formula that is used for a very wide variety of plants.

I’m not certain that I would diverge from the regular jack’s formula with only those things. If you wanted to try reducing nitrogen in late flower, I would try to get some solution grade calcium sulfate (fine powder) or calcium chloride. Either one would give you a simple way to accomplish that.

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What happens if you just drop everything except 5-12-25?

And how tf do you figure out what all else is in that? I couldn’t plug anything in to any app if I wanted to bc you have to know that. How do you know “potassium nitrate” or whatever is in it?? :sweat:

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