Check My Math: Adding Disodium EDTA to Your HydroBuddy Nutrient Recipe?

[ExNavyInSTL]

I would like someone who makes their own fertilizer to check my math.

I've learned Hydro Buddy and I have created my "ideal" nutrient recipe (in theory).

However, I want to make sure I understand the formula for adding Disodium EDTA to chelate my Fe, Mn, Zn & Cu.

From what I have extrapolated from Dr. Daniel Fernandez's various comments at the bottom of his DIY Nutrient videos on YouTube, it goes something like this.

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1) After Final Recipe has been chosen and concentrated (i.e. 1 Liter @ 200:1),
you take the millimolar concentration amount and change 'ppm' to mM' on "Main Page."

After Switching to 'mM," it looks like this:

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2) Once you have the millimolar concentration, you add up the 4 numbers:

Fe: 4.298E-02
Mn: 9.101E-03
Zn: 3.363E-03
Cu: 4.721E-03
-------------------
= 6.02E-02 (0.0602)

Actually it is: 0.060165

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3) Once you establish this number:

Multiply by the concentration Amount (200:1). It would be multiply by 100 if 100:1.

0.060165 x 200
= 12.033

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4) Next he likes to add 20 or 25% for safety.

12.033 x 1.25
=15.041

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5) Now you take your "safe" total and multiply by the molar mass of Disodium EDTA (336.21) for your grams:

15.0412 x 0.33621

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That leaves you with the grams required.

However, the number isn't necessairly complete.
In this case it is, but if amount was 0.5 liter it would be differnet.

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For Final Number, Multiply grams by volume of concentration (1 Liter):

5.06 x 1.00
= 5.06 grams

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If it it were for 0.5 liters, then it would be :
5.06 x 0.5
=2.53 grams

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Below I'll show an example (not final) of my "template" worksheet:

Items in RED are to remind me to double check things that can change:

 

[ExNavyInSTL]

I just hope I put it in a form so that people who do know what I am talking about can make sense of it.

Here is a little more background. The first is a screenshot from me. His answer had me going back to my college chemistry classes (I got Ds in both).

I was suddenly using a periodic table to get molar mass, then going to calculators for molar concentration, etc.

Then in another video's comments, he put it in a way that made the lightbulb go on in my head. HydroBuddy already had molar concentration inside. You just had to change one setting.

From that answer, I was able to formulate the question above (I hope).

 

[ExNavyInSTL]

I got my answer. Even better, this way is more concise.

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I should add: I hope I got my answer.

To complete the calculation determining the amount of Disodium EDTA needed for proper chelation, you will need to know:

(1) Elemental PPMS of the 4 metals (comes from HydroBuddy (see bottom section of my attachment)

(2) Molecular Weight of the exact formula for your metal.
For example, my Fe is Iron Sulphate - Heptahydrate (Fe2H14O19S3) - 278.01 g/mol
Just Google the Formula to get your Molecular weight

(3) Once you have those 2 things, you are off to the races.

Special Note: I am just a guy on the internet. I would trust me as much as you would a teenage boy taking your daughter on a first date to a 10-kegger party.

Also, my phrases (i.e. Molecular weight, vs. molar mass, etc.) may be off, but the math solutions should be correct.

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Calculations to complete in this order:

(a) Divide individual metal element's PPM by molecular weight:

For example, in my scenario I have 2.4 ppm of my Fe and we know the molecular weight is 278.01

2.4 / 278.01 = 0.00863

(b) Add (by multiplying) 20 to 25% to this number for a safety factor.
I'm going with 25% because of my inexperience.

0.00863 x 1.25 = 0.0108

(c) Next, multiply your 25% padded number by the molecular weight of Disodium EDTA (372.24)
In my case the m. weight was listed on my container.

0.0108 x 372.24 = 4.017

(d) Do these steps for all four of your metals to chelate.

To expedite, here are all four of my values

Fe: 4.017 grams
+ Mn: 1.541
+ Zn: 0.634
+ Cu: 0.559
--------------------
6.751 grams of Disodium EDTA

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Below, I will attach my updated "Template in the Making." I say in the making because I seem to change it every day.

I put in the formulas for all of the math, so it isn't a big deal after the first time. Of course, I still triple-check my formulas. So, it's a wash. : )

I know I can't be the only person who said they wanted to make their own nutrients, who didn't want to buy them already chelated or in a multi-metal mix (i.e. Peter's S.T.E.M.)

I'll report back if I kill my plants or my wife's tomatoes.