That’s horrible what do you mean new veg new bloom ? Are they change the formulation of salts without say that on BAG label ?
The Athena nutrients sucks the most thats why they aways try to comes out with something new,I believe that guy “Richard Durand” I think there them nutrients formulation guy cause that’s how he present him self I’m YouTube.so I believe it’s all marketing and they are good on that but in my opinion they suck in the nutrients formulations.2 days ago they mentioned Will go in corporation with Bruce bgee,that’s only can mean they are not enough educated to do it without him. So they posted a pictures with him a d I believe they hope that’s gonna make them sells better,but won’t change the fact that they wacking in B in the solution,I actually think they just make pictures with him for.instagram marketing I don’t think he will corporate with them. Or they just can buy his utah state lectures for 1500$ and reize they have to increase CU to 1 ppm if they wanna achieve higher amount in the tissue cause they have found that CU bonds to the coco coir or peat moss well.i think you’re are in those lectures too no ?
I think you’re right vpd of 0.9-1.0 it’s Great I’m personaly aiming for 1.0 but if fluxuated to 0.9-1.2vpd but It is what it is, the CO2 definitely gonna help with the hollow stems,cause of the the C from the CO2,so if someone told you you don’t need CO2 in veg or stretch don’t listen to them 
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You for sure make right decision I keep watching what’s on the bag and last calculation I made turns out 1:10 Fe to mn ratio 4 grams core and 7 grams bloom. I hope I’m wrong. If not those guys are moroons
Would you mind elaborating on the anion:cation balance and the effect on pH. I ask because from my understanding all aqueous solutions must adhere to the law of electro neutrality. All fertilizers them selves are balanced by nature. If we look at Yaraliva 15.5-0-0 with 19% Calcium and interpret the anion to cation balance we find it completely cancels out. 100mg/Liter of Yaraliva will produce .95 meq/L Ca + 0.8 meq/L N-NH4 = 1.03 and then you yield 1.03 meq/L from N-NO3, zeros out, due to the law of electro neutrality. I am interested to learn more about your theory/reasoning on imbalance and effect on pH. As I understand the effect on pH is from protonation of Hydrogen ions when the fertilizers them selves disassociate. If I am wrong please feel free to correct me.
Can we tag @danielfp to get his thoughts?
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The sum of the molar concentration of anions times their charge is always equal to the sum of the molar concentration of cations times their charge. No solution is ever under a “charge imbalance” as all solutions follow the law of electrical neutrality.
With that said, the practice of calculating the sum of the molar concentration of nutrient cations times their charge and comparing it to the anion counterpart was popularized by Steiner in the 80s and has been used by many people since then, although not in academia, for reasons that will become apparent within the next few paragraphs.
When you do such a calculation, you end up with a number that is likely not balanced because you’re ignoring certain ions in the solution. If you are accounting for all mineral nutrients, then this lack of balance in your calculations could be interpreted in some cases to create solutions that will lead to unfavorable starting conditions, basically because the starting pH won’t be adequate. This is because the ions you ignore are commonly OH- and H+ so an excess of anions would indicate that you’re not accounting for H+ - meaning your starting pH would be too low - the opposite for an excess of cations.
However, omission of ions like chlorides, carbonates, acetates, etc, often causes this calculation along with its interpretation, to be completely wrong . As I mentioned, no one that I know of in academia favors doing this calculation today because its scope is very limited and now a days we have much better tools to assess the quality and design of nutrient solutions.
For example, we can use tissue analysis to create formulations that cater to the tissue composition that is needed by the plant, we also have pH meters to allow us to correct solutions easily if the starting pH values are not adequate. This is a tool from the 80s that served its purpose but is not needed and imo shouldn’t be used anymore. It leads to more inaccurate uses and misinterpretations than it helps, often making people grossly misunderstand what’s going on. This is the main reason why I have never added it to HydroBuddy’s calculations.
Now about pH. The pH depends on the concentration of H+ in solution, as it is defined as -Log(|H+|) (we use |X| to denote the molar concentration of X).
The concentration of H+ depends on the mass balance, the charge balance and the chemical equilibria present in the solution. For example, if you add monopotassium phosphate (KH2PO4) to a solution, the following equilibria exist:
kw = |OH-|*|H+|
k1 = |H+|*|H2PO4-|/|H3PO4|
k2 = |H+|*|HPO4-2|/|H2PO4|
k3 = |H+|*|PO4-3|/|HPO4|
The following charge balance also needs to be true:
|H2PO4-|+2*|HPO4-2|+3*|PO4-3|+|OH-| = |H+| + |K+|
The following mass balance is also true:
|total P| = |H2PO4-|+|HPO4-2|+|PO4-3|+|H3PO4|
The values for kw, k1, k2 and k3 are known, the value for total P is also known (the initial amount you added) and |K+| is also known (it’s equal to total P). You can then solve the above system of equations for |H+|, then calculate -Log(|H+|) to calculate the pH.
As a side product you also get values for the concentrations of all ions that you did not add directly (HPO4-2, H3PO4, PO4-3), but were formed as a consequence of the reactions of the H2PO4- ion with the water.
For any system of chemicals in water, all you need to calculate the pH is which equilibria involving protons are present, what the global charge balance involving all charged species is and create a mass balance equation for each set of species present. I give you a more detailed example in my blog post involving phosphate and carbonate here (https://scienceinhydroponics.com/2020/05/understanding-the-carbonic-acid-bicarbonate-buffer-in-hydroponics.html).
As you can see, charge balance is involved in the calculation of pH, but in this case following the law of electrical neutrality and actually using it in the context of the concentrations of ALL species in solution. I generally use the Maxima open source CAS to solve this type of problem but you certainly use MatLab or Mathematica or any other capable CAS as well.
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Also another entirely different point is how the uptake of nutrients by the plant affects pH of the root zone, I have a youtube video about that to be released next Tuesday, showing you how and why this happens and why this is often necessary to create healthy tissue compositions.
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I know for sure it’s not gas haus , I talk to both of them.
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Daniel,
Thank you very much for your thorough response.
If it is okay I would like to summarize/recap what you stated.
-
No solution is ever under a charge imbalance. All solutions follow the law of electrical neutrality. Cation Meq/L = Anion Meq/L.
-
Accounting for only mineral nutrients will most likely leave you with an imbalance.
-
When performing calculations for Anion and Cation Meq/L, if an imbalance appears to be present it is because certain ions are being ignored, such as HCO3-, CO3-, H+, Cl-, etc. All solutions must balance electrically.
-
An excess in Anion Meq/L indicates you are not accounting for H+ ions into your calculations (All solutions must be balanced due to law of electrical neutrality). Conversely an excess in Cation Meq/L indicates you are not accounting for Bicarbonates or Carbonates. Therefore an excess in either Anion or Cation Meq/L indicates an ion unaccounted for.
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pH depends on the concentration of H+ ions in solution. (This goes back to your point of ions being ignored and unaccounted for when calculating Meq/L. When there appears to be an excess of Anion Meq/L, the pH is acidic because of the presence of Hydrogen ions, not because the Anion Meq/L appears to be greater than Cations.) (Likewise when calculating Cation Meq/L and it appears to be in excess the pH is likely higher (basic) due to unaccounted for Bicarbonates and Carbonates in the solution.)
As for the Hydrogen ion concentrations/calculations that is where I am lost, haha.
I think I understand your point as to why this method has served its purpose. I would like to learn more and have a better understanding of pH calculations.
I completely agree with you on the tissue testing and correlating the analysis to the nutrient solution. I do have some experience formulating solutions using single salts along with tissue analysis results. I am more than happy to share them with you. A proven working solution listed below.
N: 215.4
P: 78.4
K: 308.0
Ca: 228.0
Mg: 89.0
S: 101.0
Fe: 4.1
Mn: 2.1
B: 0.62
Zn: 0.72
Cu: 0.30
Mo: 0.16
Cl: 72.0
This above solution put the tissue analysis within sufficient range for all elements. The flower solution the N is lowered and K and S increased, along with some micros as needed.
- An excess in Anion Meq/L indicates you are not accounting for H+ ions into your calculations (All solutions must be balanced due to law of electrical neutrality). Conversely an excess in Cation Meq/L indicates you are not accounting for Bicarbonates or Carbonates. Therefore an excess in either Anion or Cation Meq/L indicates an ion unaccounted for.
Note that the anion excess indicates that you “might” not be accounting for H+, you could also be missing another cation (for example Na+, NH4+). In the case of cations you “might” not be counting conjugate bases of organic acids, carbonates, and bicarbonates, but most notably you are also not counting OH-.
The point is that if there’s an imbalance you are not accounting for something but you don’t know exactly what that might be. If you were accounting for everything, no imbalance would exist. The usefulness of this method stems from making assumptions about what is missing, when these are wrong, it leads to wrong conclusions.
I completely agree with you on the tissue testing and correlating the analysis to the nutrient solution. I do have some experience formulating solutions using single salts along with tissue analysis results. I am more than happy to share them with you. A proven working solution listed below.
Thanks for sharing your formulation.
Just to be clear, I mean following an approach based on the desired mineral analysis of the tissue and the water use efficiency of the plants to calculate the concentrations needed in solution to obtain the desired tissue (see the approach explained here Sustainability | Free Full-Text | Principles of Nutrient and Water Management for Indoor Agriculture). This approach is especially useful for macronutrients.
For example, under such an analysis it would be clear that cannabis tissue (usually 0.2-0.4% S in leaf tissue) wouldn’t need more than 15-20 ppm of S in solution when grown under a water use efficiency of 3.5g/L (meaning 3.5g of dry tissue weight are grown for every liter of water transpired). Indeed, this can be done with no problems.
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Yes of course, thank you for catching that error!
I always wondered if that could be done. The ability to calculate the concentrations needed in solution to obtain the desired tissue values.
Based on your example above and the level of S in my solution it would appear there is a very low water use efficiency. I am achieving .230-.320 % S in tissue at 101 ppm S in solution. Very interested to read and learn more about this practice. Any further information is welcome and greatly appreciated.
The example you gave above of 15-20 ppm S in solution and being grown under a water use efficiency of 3.5g/L. Can you elaborate, does this apply to all crops? How does type of growing media effect this approach, such as rockwool or coco coir?
The uptake of S in cannabis plants is quite limited at the pH values used in soilless growing, you are feeding 100+ ppm but the plant is only using at most 15-20ppm, so you are feeding a lot of unecessary S. The tissue composition shows this. You could up your S to 200ppm, the plant would hardly take more S. If you fed only 30ppm of S, I bet your tissue S would look exactly the same it does now.
If you design solutions targeting tissue compositions, several observations like the one above will become clearer.
Note that in cannabis - as you and most here probably already know - you will need to change formulations based on the composition of the tissue grown. Since mineral composition of flower is quite different to leaves, changing nutrients in flower is necessary to cater to the now different tissue being grown.
Most plants will grow under WUE values between 3-6 g/L, depending on environmental conditions and plants species. For example CO2 supplementation will tend to increase WUE significantly as it closes plant stomata.
I advice you study the paper I linked - and the literature it cites - if you want to learn more about the subject.
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Forgive my ignorance, but when you say sulfur uptake in cannabis is “saturated” quite fast at a pH of 5.5-6. What exactly do you mean? In your experience what pH is most suitable for Sulfur uptake to prevent build up in media?
This means that a pH of 5.5-6.0 a cannabis plant simply cannot really uptake more than 15-20 ppm of S from solution, neither does it need to as it can produce healthy tissue with just that. Sulfur uptake becomes more difficult for plants as pH drops, at a pH <5 sulfur deficiencies are common in many plants, even if you have ample sulfur in solution.
If you wanted significantly more sulfur uptake you would need to either increase the pH too aggressively (>7 which would lead to other problems) or use a different sulfur source than sulfate (sulfur containing organic molecules, which have their own problems).
However the plant just doesn’t need it. Healthy tissue is around 0.2-0.4% S and that requires 15-20ppm in solution. So… you just don’t have to add more than that, at least as far as S uptake goes. If you feed more than 20-30ppm, you are definitely going to accumulate sulfate in the media.
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Reading over that paper you linked right now. Thank you for that!
As I am reading it, I would like to get your opinion in regards to the calculation and one of your previous notes.
Looking at my formula I posted and using the link/calculations you provided please correct me if this is wrong.
Feeding at 215 ppm in Veg and achieving approximately 4.5% N in tissue using the formulae provided that would mean there is WUE of about 4.75g/L. Is this stated properly?
,
(4 mg S desired / 1g leaf tissue) x ( 3.5 g leaf tissue / 1 L water) = 14ppm Sulfur to achieve the desired 0.4% S in leaf tissue at 3.5g/L WUE. This is correct?
Using my S ppm in feed solution (101ppm) along with S tissue content(0.32%).
(3.2 mg S / 1g leaf tissue) x (31.5 g leaf tissue / 1 L water) = 101 ppm Sulfur. Is this correct?
Thank you!
Feeding at 215 ppm in Veg and achieving approximately 4.5% N in tissue using the formulae provided that would mean there is WUE of about 4.75g/L. Is this stated properly?
Yes. Since nitrogen can be taken up almost quantitatively by the plant (it is hard to saturate N uptake) you can use the N number to derive an approximate WUE. In this case, your WUE will be 4.75g/L (common for cannabis under CO2 enrichment).
(3.2 mg S / 1g leaf tissue) x (31.5 g leaf tissue / 1 L water) = 101 ppm Sulfur. Is this correct?
No, that is incorrect. You cannot calculate your WUE from your sulfur values. It is not like your plant is taking up ALL the sulfur and building tissue with it (which would give a ridiculously high WUE as you see in your calculation). What happens is that your plant is at a modest WUE (4.75g/L), it’s excluding most of the sulfur, and it’s building tissue with only a small fraction of it.
For a WUE of 4.75% g/L and a sulfur composition of 0.3%, your plant is using 14.25ppm of S from your solution, excluding all the rest.
As I pointed before, you are just adding a lot of sulfur that the plant is not using, therefore it’s just probably accumulating in your media.
The WUE is a global property of the plant. All elements are working under the same WUE. The reason why you see low S, is not because the plant has a very high WUE, it is because your S in solution is being excluded.
Take your tissue analysis and, assuming your WUE of 4.75%, calculate what the values in solution should be for all your macro nutrients, then compare that to what you’re feeding. You’ll then see how your solution deviates from what the plant is using to actually build tissue. If you feed it what it wants to create the tissue, it will do better.
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That makes sense! I was thinking it seemed too high, 31.5 grams of leaf tissue per liter of water.
What is the highest WUE you have seen in Cannabis?
Thank you!
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Using the solution below here are three tissue samples taken from three different varieties, all same age in same room same variables, only difference is variety.
N: 215.4
P: 78.4
K: 308.0
Ca: 228.0
Mg: 89.0
S: 101.0
Fe: 4.1
Mn: 2.1
B: 0.62
Zn: 0.72
Cu: 0.30
Mo: 0.16
Cl: 72.0
Tissue Results for Variety A:
N: 4.69% , P: 0.50% K: 2.5%, Ca: 4.9%, Mg: 1.00% , S: 0.34%,
Tissue Results for Variety B:
N: 4.7%, P: 0.60% K: 3.5%, Ca: 3.0%, Mg: 0.94%, S: 0.39%
Tissue Results for Variety C:
N: 4.3%, P: 0.68%, K: 3.7%, Ca: 3.1%, Mg: 1.2%, S: 0.29%
Using Potassium as an example. Variety C, with a tissue value of 3.7% K and a WUE of 4.75 g/L. That plant was being fed 308 ppm of Potassium in solution. What you are saying, is of that 308 ppm only 176ppm of that is being utilized to build that 3.7% K tissue and the rest (132 ppm K) is excluded?
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Yes, the plants are only using 176ppm of K from your solution to grow leaves. That’s what they can uptake given the conditions. The rest is just being left over by the plants.
This is likely because your Mg is too high, it very effectively antagonizes K+ uptake, as it has a much lower mass and twice the charge. One ppm of Mg can compete with the uptake of around 4 ppm of K. This is the reason why K:Mg ratios are commonly 4:1 or higher.
There is a lot of nuance to WUE based solution design and to the building of solutions that cater to proper tissue. I think the first thing you should probably ask is : What tissue composition should I be aiming for? The easiest is probably to find a high yielding grower willing to give you some tissue for you to analyze so you can test and compare. In veg cater to the leaf tissue, in flower cater to leaves initially, then move to cater to the flower tissue.
If you cannot find one, then the leaf tissue data given here (Hemp Leaf Tissue Nutrient Ranges: Refinement of Reference Standards for Floral Hemp | NC State Extension Publications) is a good starting point.
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Hey,
I don’t want to question your knowledge, because I learnt a lot from your posts in the past!
As soon as I installed HydroBuddy, a new world full of profile tweaking and experimentation showed up.
That being said, every source I found says that it’s actually the other way around - potassium locks out magnesium.
So, as you can guess, I’m quite confused…
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