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

[ExNavyInSTL]

I totally get those of you who are saying (or thinking) that doing all this sounds like a pain in the ass.

Up to this point, the process is fun for me.

It's not all my fault, I watched this video by Dr. Daniel Fernandez (creator of HydroBuddy and owner of Science in Hydroponics).

He makes it look so easy. So, I went to Custom Hydro (and some Amazon) and bought all the components. Then I hit this EDTA wall.

I had the scales, beakers and magnetic stirrer already, but I did have to buy the Volumetric Flasks.

Making your own masterblend proxy from scratch (DIY)

P.S. I wasn't trying to make my own MasterBlend. I was just learning the DIY concepts.

 

[RottyRzr]

I totally get those of you who are saying (or thinking) that doing all this sounds like a pain in the ass.

Up to this point, the process is fun for me.

It's not all my fault, I watched this video by Dr. Daniel Fernandez (creator of HydroBuddy and owner of Science in Hydroponics).

He makes it look so easy. So, I went to Custom Hydro (and some Amazon) and bought all the components. Then I hit this EDTA wall.

I had the scales, beakers and magnetic stirrer already, but I did have to buy the Volumetric Flasks.

Making your own masterblend proxy from scratch (DIY)

P.S. I wasn't trying to make my own MasterBlend. I was just learning the DIY concepts.

Glad the process is fun for you. Great learning experience also. Go for it.
I recently downloaded HydroBuddy but haven't messed with it too much. Can you recommend a resource for learning the app?

 

[ExNavyInSTL]

@RottyRzr

I went to a couple of videos on YouTube to learn. I would start with these (at bottom of post).

Just keep in mind, some are showing how to dial in what you need to make a gallon of something.

For instance, if you want to break down your current nutes to see the "elemental" ppms. Or do like I am and juggle ingredients to work out the "perfect" recipe. Note: Perfect = sarcasm. : )

I say juggle because some ingredients are combination products, like calcium nitrate. You fiddle with one, you are moving the other (Ca vs N).

The other way is to work out your concentrated solution.

What I do is once I work out the gallon numbers. I then switch over to 1.00 or 0.5 liters and either 100:1 or 200:1 concentrations. When you figure out the concentration, get ready for the grams required to jump up.

These screenshots are not conclusive but will help with some road bumps.

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Videos I used to get started learning:

Note: Age Restrictions are because of Cannabis mentioned or something.

 

[G.O. Joe]

I totally get those of you who are saying (or thinking) that doing all this sounds like a pain in the ass.

More like another opportunity to get ripped off by inorganic chemical suppliers, like you can't win. I wonder if some available commercial micro formulation is close enough for that part.

If you didn't notice, the Israeli group used 80/20 NO3/NH4. Perhaps this might influence your choice of P input.

 

[ExNavyInSTL]

@Dr.Mantis

I've done my homework, with some different rounding but very close.

Additionally, these numbers assume the Molar Weight of Disodium EDTA is 372.24.

If I need to switch it back to 292.24g/mol, let me know.

Edit to add:

Thanks again. I've had these salts sitting next to me for 2 weeks. I was afraid to move forward until I figured out the EDTA stuff.

One other question: Do you have a golden rule for adding your preservative? In my case my preservative of choice is Sodium Benzoate.

From what I've read, some say 0.025% to 0.1%. I've also read 0.1 to 0.3g is enough.

I just don't know if the percentages were based on weight or liquid volume.

Hey thanks for sharing. On your EDTA worksheet you have your transition metal micros under molar mass as "Fe = 55.85 g/mol (heptahydrate)", for example. Is that number the calculated amount of iron per mol of the selected salt?

To me its easier to just divide the target mass of the salt by the molecular weight to give moles, check stoichiometry, apply correction factor.

So for FeSO4 x7H20: 278.01g/mol
Na2EDTA: 292.24g/mol
Desired reaction FeSO4 + Na2(EDTA) --> [(FeEDTA)Na2)] SO4

1. Hydrobuddy says you need 2.394g of FeSO4 x7H20
2. So, (2.394g/278.01g/mol) = .008611 mol of ferrous sulfate
3. Apply 25% correction factor. .008611mol x 1.25 = .01076mol
4. .01076mol x 292.24g/mol = 3.145g of Na2EDTA for 2.394g of FeSO4 hepta hydrate.
5. Repeat for your other salts based on their molecular weights

 

[Dr.Mantis]

Y

That is what I was looking for. Thank you so much. I was just looking at the mass of the Fe portion and not including the Sulfate part. So your listed molar weight makes sense to me.

However, I am not sure if this matters, but on the bottle containing my Disodium EDTA, it says it has a molecular weight of 372.24.

This Disodium EDTA is from HiMedia Labs (India).

If I am to make the change for the new Mol Wt

Should I change out?:

Na2EDTA: 292.24g/mol

to

Na2EDTA: 372.24g/mol

Otherwise, that is the breakdown I was looking for.

You have earned a basket full of good Karma Points. : )

Yup, use the MW provided on the bottle. That salt is the di hydrate, so it has two water molecules stuck in its crystal lattice per edta, hence the change in MW. The same applies to your salts. For instance iron sulfate heptahysrate has a much higher mw than the anhydrous salt.

Let me know if you have any other questions, I’m happy to help where I can!

EDIT:

Hey double check your MnSO4, its usually sold as the monohydrate which has a slighter higher MW, same for your ZnSO4. The math looks good though!

Ive never used preservatives in my stuff. I usually keep my nutrients as a powder (dry climate here) and mix as needed. I would go by the final volume as weight percent, so for 200ml = ~200g x .001 Benzoate. Depending on how much stock solution you go through, you could probably skip the benzoate and just keep it in the fridge (dont mistake it for gatorate though!).

 

[Charles Dankens]

They did allow for a generous range to fiddle with, but they do show when the differences matter.

Sometimes creating more bio-mass is what happens with the extra nutrients, but they don't do much for more flower mass.

The funny part is that the highest THC and other cannabinoids were at their peak if they were practically starved the whole time.

Sure, the plants look like shit, but for those seeking more THC and more terpenes, you gotta make them hungry and ugly. : )

Another interesting thing from her lecture is how Humics had a negative effect.

She even covers how feeding them in certain ways (differently) enhances or depresses certain cannabinoids. Like Pheno Hunting, you can go Terp Hunting, if you have a favorite.

What is surprising is their study MythBusts the claim that you have to add more P & K as you go into flower.

All those Bloom nutes might just be Snake Oil?

They are working on more of the nutrients. I am interested to see what is a sweet spot for calcium ... and if you really need about half of the Ca amount for the Mg.

As far as her observation about the effects of humics, from the materials and methods section it seems humics were applied with every watering. I would not expect a positive effect from that regimen. There are a few threads on grow sites discussing this information. Do you have any thoughts on the humic application rate?